]> git.sesse.net Git - bcachefs-tools-debian/blobdiff - libbcachefs/fs-io.c
Update bcachefs sources to e48731a188 bcachefs: Fix BTREE_TRIGGER_WANTS_OLD_AND_NEW
[bcachefs-tools-debian] / libbcachefs / fs-io.c
index 7693520d4675b61ee3d24982520cf396924cc179..b05d6e896f034935c7dbf2f13c61b0154108d038 100644 (file)
@@ -1,10 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0
 #ifndef NO_BCACHEFS_FS
 
 #include "bcachefs.h"
+#include "alloc_foreground.h"
+#include "bkey_buf.h"
 #include "btree_update.h"
 #include "buckets.h"
 #include "clock.h"
 #include "error.h"
+#include "extents.h"
+#include "extent_update.h"
 #include "fs.h"
 #include "fs-io.h"
 #include "fsck.h"
@@ -13,6 +18,7 @@
 #include "io.h"
 #include "keylist.h"
 #include "quota.h"
+#include "reflink.h"
 
 #include <linux/aio.h>
 #include <linux/backing-dev.h>
@@ -20,6 +26,8 @@
 #include <linux/migrate.h>
 #include <linux/mmu_context.h>
 #include <linux/pagevec.h>
+#include <linux/rmap.h>
+#include <linux/sched/signal.h>
 #include <linux/task_io_accounting_ops.h>
 #include <linux/uio.h>
 #include <linux/writeback.h>
 #include <trace/events/bcachefs.h>
 #include <trace/events/writeback.h>
 
-struct quota_res {
-       u64                             sectors;
-};
+static inline bool bio_full(struct bio *bio, unsigned len)
+{
+       if (bio->bi_vcnt >= bio->bi_max_vecs)
+               return true;
+       if (bio->bi_iter.bi_size > UINT_MAX - len)
+               return true;
+       return false;
+}
 
-struct i_sectors_hook {
-       struct extent_insert_hook       hook;
-       struct bch_inode_info           *inode;
-       struct quota_res                quota_res;
-       s64                             sectors;
-       u64                             new_i_size;
-       unsigned                        flags;
-       unsigned                        appending:1;
-};
+static inline struct address_space *faults_disabled_mapping(void)
+{
+       return (void *) (((unsigned long) current->faults_disabled_mapping) & ~1UL);
+}
 
-struct bchfs_write_op {
-       struct bch_inode_info           *inode;
-       s64                             sectors_added;
-       bool                            is_dio;
-       bool                            unalloc;
-       u64                             new_i_size;
+static inline void set_fdm_dropped_locks(void)
+{
+       current->faults_disabled_mapping =
+               (void *) (((unsigned long) current->faults_disabled_mapping)|1);
+}
 
-       /* must be last: */
-       struct bch_write_op             op;
+static inline bool fdm_dropped_locks(void)
+{
+       return ((unsigned long) current->faults_disabled_mapping) & 1;
+}
+
+struct quota_res {
+       u64                             sectors;
 };
 
 struct bch_writepage_io {
        struct closure                  cl;
-       u64                             new_sectors;
+       struct bch_inode_info           *inode;
 
        /* must be last: */
-       struct bchfs_write_op           op;
+       struct bch_write_op             op;
 };
 
 struct dio_write {
-       struct closure                  cl;
+       struct completion               done;
        struct kiocb                    *req;
-       struct task_struct              *task;
+       struct mm_struct                *mm;
        unsigned                        loop:1,
                                        sync:1,
                                        free_iov:1;
        struct quota_res                quota_res;
+       u64                             written;
 
        struct iov_iter                 iter;
        struct iovec                    inline_vecs[2];
 
        /* must be last: */
-       struct bchfs_write_op           iop;
+       struct bch_write_op             op;
 };
 
 struct dio_read {
        struct closure                  cl;
        struct kiocb                    *req;
        long                            ret;
+       bool                            should_dirty;
        struct bch_read_bio             rbio;
 };
 
@@ -94,8 +108,7 @@ static int write_invalidate_inode_pages_range(struct address_space *mapping,
         * is continually redirtying a specific page
         */
        do {
-               if (!mapping->nrpages &&
-                   !mapping->nrexceptional)
+               if (!mapping->nrpages)
                        return 0;
 
                ret = filemap_write_and_wait_range(mapping, start, end);
@@ -124,13 +137,13 @@ static void bch2_quota_reservation_put(struct bch_fs *c,
        if (!res->sectors)
                return;
 
-       mutex_lock(&inode->ei_update_lock);
+       mutex_lock(&inode->ei_quota_lock);
        BUG_ON(res->sectors > inode->ei_quota_reserved);
 
        bch2_quota_acct(c, inode->ei_qid, Q_SPC,
-                       -((s64) res->sectors), BCH_QUOTA_PREALLOC);
+                       -((s64) res->sectors), KEY_TYPE_QUOTA_PREALLOC);
        inode->ei_quota_reserved -= res->sectors;
-       mutex_unlock(&inode->ei_update_lock);
+       mutex_unlock(&inode->ei_quota_lock);
 
        res->sectors = 0;
 }
@@ -143,14 +156,14 @@ static int bch2_quota_reservation_add(struct bch_fs *c,
 {
        int ret;
 
-       mutex_lock(&inode->ei_update_lock);
+       mutex_lock(&inode->ei_quota_lock);
        ret = bch2_quota_acct(c, inode->ei_qid, Q_SPC, sectors,
-                             check_enospc ? BCH_QUOTA_PREALLOC : BCH_QUOTA_NOCHECK);
+                             check_enospc ? KEY_TYPE_QUOTA_PREALLOC : KEY_TYPE_QUOTA_NOCHECK);
        if (likely(!ret)) {
                inode->ei_quota_reserved += sectors;
                res->sectors += sectors;
        }
-       mutex_unlock(&inode->ei_update_lock);
+       mutex_unlock(&inode->ei_quota_lock);
 
        return ret;
 }
@@ -176,28 +189,52 @@ static int bch2_quota_reservation_add(struct bch_fs *c,
 
 /* i_size updates: */
 
+struct inode_new_size {
+       loff_t          new_size;
+       u64             now;
+       unsigned        fields;
+};
+
 static int inode_set_size(struct bch_inode_info *inode,
                          struct bch_inode_unpacked *bi,
                          void *p)
 {
-       loff_t *new_i_size = p;
+       struct inode_new_size *s = p;
 
-       lockdep_assert_held(&inode->ei_update_lock);
+       bi->bi_size = s->new_size;
+       if (s->fields & ATTR_ATIME)
+               bi->bi_atime = s->now;
+       if (s->fields & ATTR_MTIME)
+               bi->bi_mtime = s->now;
+       if (s->fields & ATTR_CTIME)
+               bi->bi_ctime = s->now;
 
-       bi->bi_size = *new_i_size;
        return 0;
 }
 
-static int __must_check bch2_write_inode_size(struct bch_fs *c,
-                                             struct bch_inode_info *inode,
-                                             loff_t new_size)
+int __must_check bch2_write_inode_size(struct bch_fs *c,
+                                      struct bch_inode_info *inode,
+                                      loff_t new_size, unsigned fields)
 {
-       return __bch2_write_inode(c, inode, inode_set_size, &new_size);
+       struct inode_new_size s = {
+               .new_size       = new_size,
+               .now            = bch2_current_time(c),
+               .fields         = fields,
+       };
+
+       return bch2_write_inode(c, inode, inode_set_size, &s, fields);
 }
 
-static void __i_sectors_acct(struct bch_fs *c, struct bch_inode_info *inode,
-                            struct quota_res *quota_res, int sectors)
+static void i_sectors_acct(struct bch_fs *c, struct bch_inode_info *inode,
+                          struct quota_res *quota_res, s64 sectors)
 {
+       if (!sectors)
+               return;
+
+       mutex_lock(&inode->ei_quota_lock);
+       BUG_ON((s64) inode->v.i_blocks + sectors < 0);
+       inode->v.i_blocks += sectors;
+
 #ifdef CONFIG_BCACHEFS_QUOTA
        if (quota_res && sectors > 0) {
                BUG_ON(sectors > quota_res->sectors);
@@ -206,515 +243,553 @@ static void __i_sectors_acct(struct bch_fs *c, struct bch_inode_info *inode,
                quota_res->sectors -= sectors;
                inode->ei_quota_reserved -= sectors;
        } else {
-               bch2_quota_acct(c, inode->ei_qid, Q_SPC, sectors, BCH_QUOTA_WARN);
+               bch2_quota_acct(c, inode->ei_qid, Q_SPC, sectors, KEY_TYPE_QUOTA_WARN);
        }
 #endif
-       inode->v.i_blocks += sectors;
+       mutex_unlock(&inode->ei_quota_lock);
 }
 
-static void i_sectors_acct(struct bch_fs *c, struct bch_inode_info *inode,
-                          struct quota_res *quota_res, int sectors)
-{
-       mutex_lock(&inode->ei_update_lock);
-       __i_sectors_acct(c, inode, quota_res, sectors);
-       mutex_unlock(&inode->ei_update_lock);
-}
+/* page state: */
 
-/* i_sectors accounting: */
+/* stored in page->private: */
 
-static enum btree_insert_ret
-i_sectors_hook_fn(struct extent_insert_hook *hook,
-                 struct bpos committed_pos,
-                 struct bpos next_pos,
-                 struct bkey_s_c k,
-                 const struct bkey_i *insert)
-{
-       struct i_sectors_hook *h = container_of(hook,
-                               struct i_sectors_hook, hook);
-       s64 sectors = next_pos.offset - committed_pos.offset;
-       int sign = bkey_extent_is_allocation(&insert->k) -
-               (k.k && bkey_extent_is_allocation(k.k));
+struct bch_page_sector {
+       /* Uncompressed, fully allocated replicas (or on disk reservation): */
+       unsigned                nr_replicas:4;
 
-       EBUG_ON(!(h->inode->ei_inode.bi_flags & BCH_INODE_I_SECTORS_DIRTY));
+       /* Owns PAGE_SECTORS * replicas_reserved sized in memory reservation: */
+       unsigned                replicas_reserved:4;
+
+       /* i_sectors: */
+       enum {
+               SECTOR_UNALLOCATED,
+               SECTOR_RESERVED,
+               SECTOR_DIRTY,
+               SECTOR_DIRTY_RESERVED,
+               SECTOR_ALLOCATED,
+       }                       state:8;
+};
 
-       h->sectors += sectors * sign;
+struct bch_page_state {
+       spinlock_t              lock;
+       atomic_t                write_count;
+       bool                    uptodate;
+       struct bch_page_sector  s[PAGE_SECTORS];
+};
 
-       return BTREE_INSERT_OK;
+static inline struct bch_page_state *__bch2_page_state(struct page *page)
+{
+       return page_has_private(page)
+               ? (struct bch_page_state *) page_private(page)
+               : NULL;
 }
 
-static int i_sectors_dirty_finish_fn(struct bch_inode_info *inode,
-                                    struct bch_inode_unpacked *bi,
-                                    void *p)
+static inline struct bch_page_state *bch2_page_state(struct page *page)
 {
-       struct i_sectors_hook *h = p;
+       EBUG_ON(!PageLocked(page));
 
-       if (h->new_i_size != U64_MAX &&
-           (!h->appending ||
-            h->new_i_size > bi->bi_size))
-               bi->bi_size = h->new_i_size;
-       bi->bi_sectors  += h->sectors;
-       bi->bi_flags    &= ~h->flags;
-       return 0;
+       return __bch2_page_state(page);
 }
 
-static int i_sectors_dirty_finish(struct bch_fs *c, struct i_sectors_hook *h)
+/* for newly allocated pages: */
+static void __bch2_page_state_release(struct page *page)
 {
-       int ret;
-
-       mutex_lock(&h->inode->ei_update_lock);
-       if (h->new_i_size != U64_MAX)
-               i_size_write(&h->inode->v, h->new_i_size);
-
-       __i_sectors_acct(c, h->inode, &h->quota_res, h->sectors);
+       kfree(detach_page_private(page));
+}
 
-       ret = __bch2_write_inode(c, h->inode, i_sectors_dirty_finish_fn, h);
-       mutex_unlock(&h->inode->ei_update_lock);
+static void bch2_page_state_release(struct page *page)
+{
+       EBUG_ON(!PageLocked(page));
+       __bch2_page_state_release(page);
+}
 
-       bch2_quota_reservation_put(c, h->inode, &h->quota_res);
+/* for newly allocated pages: */
+static struct bch_page_state *__bch2_page_state_create(struct page *page,
+                                                      gfp_t gfp)
+{
+       struct bch_page_state *s;
 
-       h->sectors = 0;
+       s = kzalloc(sizeof(*s), GFP_NOFS|gfp);
+       if (!s)
+               return NULL;
 
-       return ret;
+       spin_lock_init(&s->lock);
+       attach_page_private(page, s);
+       return s;
 }
 
-static int i_sectors_dirty_start_fn(struct bch_inode_info *inode,
-                                   struct bch_inode_unpacked *bi, void *p)
+static struct bch_page_state *bch2_page_state_create(struct page *page,
+                                                    gfp_t gfp)
 {
-       struct i_sectors_hook *h = p;
-
-       if (h->flags & BCH_INODE_I_SIZE_DIRTY)
-               bi->bi_size = h->new_i_size;
+       return bch2_page_state(page) ?: __bch2_page_state_create(page, gfp);
+}
 
-       bi->bi_flags |= h->flags;
-       return 0;
+static unsigned bkey_to_sector_state(const struct bkey *k)
+{
+       if (k->type == KEY_TYPE_reservation)
+               return SECTOR_RESERVED;
+       if (bkey_extent_is_allocation(k))
+               return SECTOR_ALLOCATED;
+       return SECTOR_UNALLOCATED;
 }
 
-static int i_sectors_dirty_start(struct bch_fs *c, struct i_sectors_hook *h)
+static void __bch2_page_state_set(struct page *page,
+                                 unsigned pg_offset, unsigned pg_len,
+                                 unsigned nr_ptrs, unsigned state)
 {
-       int ret;
+       struct bch_page_state *s = bch2_page_state_create(page, __GFP_NOFAIL);
+       unsigned i;
 
-       mutex_lock(&h->inode->ei_update_lock);
-       ret = __bch2_write_inode(c, h->inode, i_sectors_dirty_start_fn, h);
-       mutex_unlock(&h->inode->ei_update_lock);
+       BUG_ON(pg_offset >= PAGE_SECTORS);
+       BUG_ON(pg_offset + pg_len > PAGE_SECTORS);
 
-       return ret;
-}
+       spin_lock(&s->lock);
 
-static inline struct i_sectors_hook
-i_sectors_hook_init(struct bch_inode_info *inode, unsigned flags)
-{
-       return (struct i_sectors_hook) {
-               .hook.fn        = i_sectors_hook_fn,
-               .inode          = inode,
-               .sectors        = 0,
-               .new_i_size     = U64_MAX,
-               .flags          = flags|BCH_INODE_I_SECTORS_DIRTY,
-       };
-}
+       for (i = pg_offset; i < pg_offset + pg_len; i++) {
+               s->s[i].nr_replicas = nr_ptrs;
+               s->s[i].state = state;
+       }
 
-/* normal i_size/i_sectors update machinery: */
+       if (i == PAGE_SECTORS)
+               s->uptodate = true;
 
-struct bchfs_extent_trans_hook {
-       struct bchfs_write_op           *op;
-       struct extent_insert_hook       hook;
+       spin_unlock(&s->lock);
+}
 
-       struct bch_inode_unpacked       inode_u;
-       struct bkey_inode_buf           inode_p;
+static int bch2_page_state_set(struct bch_fs *c, subvol_inum inum,
+                              struct page **pages, unsigned nr_pages)
+{
+       struct btree_trans trans;
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       u64 offset = pages[0]->index << PAGE_SECTORS_SHIFT;
+       unsigned pg_idx = 0;
+       u32 snapshot;
+       int ret;
 
-       bool                            need_inode_update;
-};
+       bch2_trans_init(&trans, c, 0, 0);
+retry:
+       bch2_trans_begin(&trans);
 
-static enum btree_insert_ret
-bchfs_extent_update_hook(struct extent_insert_hook *hook,
-                        struct bpos committed_pos,
-                        struct bpos next_pos,
-                        struct bkey_s_c k,
-                        const struct bkey_i *insert)
-{
-       struct bchfs_extent_trans_hook *h = container_of(hook,
-                               struct bchfs_extent_trans_hook, hook);
-       struct bch_inode_info *inode = h->op->inode;
-       int sign = bkey_extent_is_allocation(&insert->k) -
-               (k.k && bkey_extent_is_allocation(k.k));
-       s64 sectors = (s64) (next_pos.offset - committed_pos.offset) * sign;
-       u64 offset = min(next_pos.offset << 9, h->op->new_i_size);
-       bool do_pack = false;
-
-       if (h->op->unalloc &&
-           !bch2_extent_is_fully_allocated(k))
-               return BTREE_INSERT_ENOSPC;
-
-       BUG_ON((next_pos.offset << 9) > round_up(offset, PAGE_SIZE));
-
-       /* XXX: inode->i_size locking */
-       if (offset > inode->ei_inode.bi_size) {
-               if (!h->need_inode_update) {
-                       h->need_inode_update = true;
-                       return BTREE_INSERT_NEED_TRAVERSE;
-               }
+       ret = bch2_subvolume_get_snapshot(&trans, inum.subvol, &snapshot);
+       if (ret)
+               goto err;
 
-               BUG_ON(h->inode_u.bi_flags & BCH_INODE_I_SIZE_DIRTY);
+       for_each_btree_key_norestart(&trans, iter, BTREE_ID_extents,
+                          SPOS(inum.inum, offset, snapshot),
+                          BTREE_ITER_SLOTS, k, ret) {
+               unsigned nr_ptrs = bch2_bkey_nr_ptrs_fully_allocated(k);
+               unsigned state = bkey_to_sector_state(k.k);
 
-               h->inode_u.bi_size = offset;
-               do_pack = true;
+               while (pg_idx < nr_pages) {
+                       struct page *page = pages[pg_idx];
+                       u64 pg_start = page->index << PAGE_SECTORS_SHIFT;
+                       u64 pg_end = (page->index + 1) << PAGE_SECTORS_SHIFT;
+                       unsigned pg_offset = max(bkey_start_offset(k.k), pg_start) - pg_start;
+                       unsigned pg_len = min(k.k->p.offset, pg_end) - pg_offset - pg_start;
 
-               inode->ei_inode.bi_size = offset;
+                       BUG_ON(k.k->p.offset < pg_start);
+                       BUG_ON(bkey_start_offset(k.k) > pg_end);
 
-               if (h->op->is_dio)
-                       i_size_write(&inode->v, offset);
-       }
+                       if (!bch2_page_state_create(page, __GFP_NOFAIL)->uptodate)
+                               __bch2_page_state_set(page, pg_offset, pg_len, nr_ptrs, state);
 
-       if (sectors) {
-               if (!h->need_inode_update) {
-                       h->need_inode_update = true;
-                       return BTREE_INSERT_NEED_TRAVERSE;
+                       if (k.k->p.offset < pg_end)
+                               break;
+                       pg_idx++;
                }
 
-               h->inode_u.bi_sectors += sectors;
-               do_pack = true;
-
-               h->op->sectors_added += sectors;
+               if (pg_idx == nr_pages)
+                       break;
        }
 
-       if (do_pack)
-               bch2_inode_pack(&h->inode_p, &h->inode_u);
+       offset = iter.pos.offset;
+       bch2_trans_iter_exit(&trans, &iter);
+err:
+       if (ret == -EINTR)
+               goto retry;
+       bch2_trans_exit(&trans);
 
-       return BTREE_INSERT_OK;
+       return ret;
 }
 
-static int bchfs_write_index_update(struct bch_write_op *wop)
+static void bch2_bio_page_state_set(struct bio *bio, struct bkey_s_c k)
 {
-       struct bchfs_write_op *op = container_of(wop,
-                               struct bchfs_write_op, op);
-       struct keylist *keys = &op->op.insert_keys;
-       struct btree_iter extent_iter, inode_iter;
-       struct bchfs_extent_trans_hook hook;
-       struct bkey_i *k = bch2_keylist_front(keys);
-       s64 orig_sectors_added = op->sectors_added;
-       int ret;
+       struct bvec_iter iter;
+       struct bio_vec bv;
+       unsigned nr_ptrs = k.k->type == KEY_TYPE_reflink_v
+               ? 0 : bch2_bkey_nr_ptrs_fully_allocated(k);
+       unsigned state = bkey_to_sector_state(k.k);
+
+       bio_for_each_segment(bv, bio, iter)
+               __bch2_page_state_set(bv.bv_page, bv.bv_offset >> 9,
+                                     bv.bv_len >> 9, nr_ptrs, state);
+}
 
-       BUG_ON(k->k.p.inode != op->inode->v.i_ino);
+static void mark_pagecache_unallocated(struct bch_inode_info *inode,
+                                      u64 start, u64 end)
+{
+       pgoff_t index = start >> PAGE_SECTORS_SHIFT;
+       pgoff_t end_index = (end - 1) >> PAGE_SECTORS_SHIFT;
+       struct pagevec pvec;
 
-       bch2_btree_iter_init(&extent_iter, wop->c, BTREE_ID_EXTENTS,
-                            bkey_start_pos(&bch2_keylist_front(keys)->k),
-                            BTREE_ITER_INTENT);
-       bch2_btree_iter_init(&inode_iter, wop->c, BTREE_ID_INODES,
-                            POS(extent_iter.pos.inode, 0),
-                            BTREE_ITER_INTENT);
+       if (end <= start)
+               return;
 
-       hook.op                 = op;
-       hook.hook.fn            = bchfs_extent_update_hook;
-       hook.need_inode_update  = false;
+       pagevec_init(&pvec);
 
        do {
-               ret = bch2_btree_iter_traverse(&extent_iter);
-               if (ret)
-                       goto err;
+               unsigned nr_pages, i, j;
+
+               nr_pages = pagevec_lookup_range(&pvec, inode->v.i_mapping,
+                                               &index, end_index);
+               for (i = 0; i < nr_pages; i++) {
+                       struct page *page = pvec.pages[i];
+                       u64 pg_start = page->index << PAGE_SECTORS_SHIFT;
+                       u64 pg_end = (page->index + 1) << PAGE_SECTORS_SHIFT;
+                       unsigned pg_offset = max(start, pg_start) - pg_start;
+                       unsigned pg_len = min(end, pg_end) - pg_offset - pg_start;
+                       struct bch_page_state *s;
+
+                       BUG_ON(end <= pg_start);
+                       BUG_ON(pg_offset >= PAGE_SECTORS);
+                       BUG_ON(pg_offset + pg_len > PAGE_SECTORS);
 
-               /* XXX: inode->i_size locking */
-               k = bch2_keylist_front(keys);
-               if (min(k->k.p.offset << 9, op->new_i_size) >
-                   op->inode->ei_inode.bi_size)
-                       hook.need_inode_update = true;
+                       lock_page(page);
+                       s = bch2_page_state(page);
 
-               if (hook.need_inode_update) {
-                       struct bkey_s_c inode;
+                       if (s) {
+                               spin_lock(&s->lock);
+                               for (j = pg_offset; j < pg_offset + pg_len; j++)
+                                       s->s[j].nr_replicas = 0;
+                               spin_unlock(&s->lock);
+                       }
 
-                       if (!btree_iter_linked(&inode_iter))
-                               bch2_btree_iter_link(&extent_iter, &inode_iter);
+                       unlock_page(page);
+               }
+               pagevec_release(&pvec);
+       } while (index <= end_index);
+}
 
-                       inode = bch2_btree_iter_peek_with_holes(&inode_iter);
-                       if ((ret = btree_iter_err(inode)))
-                               goto err;
+static void mark_pagecache_reserved(struct bch_inode_info *inode,
+                                   u64 start, u64 end)
+{
+       struct bch_fs *c = inode->v.i_sb->s_fs_info;
+       pgoff_t index = start >> PAGE_SECTORS_SHIFT;
+       pgoff_t end_index = (end - 1) >> PAGE_SECTORS_SHIFT;
+       struct pagevec pvec;
+       s64 i_sectors_delta = 0;
 
-                       if (WARN_ONCE(inode.k->type != BCH_INODE_FS,
-                                     "inode %llu not found when updating",
-                                     extent_iter.pos.inode)) {
-                               ret = -ENOENT;
-                               break;
-                       }
+       if (end <= start)
+               return;
 
-                       if (WARN_ONCE(bkey_bytes(inode.k) >
-                                     sizeof(hook.inode_p),
-                                     "inode %llu too big (%zu bytes, buf %zu)",
-                                     extent_iter.pos.inode,
-                                     bkey_bytes(inode.k),
-                                     sizeof(hook.inode_p))) {
-                               ret = -ENOENT;
-                               break;
-                       }
+       pagevec_init(&pvec);
 
-                       bkey_reassemble(&hook.inode_p.inode.k_i, inode);
-                       ret = bch2_inode_unpack(bkey_s_c_to_inode(inode),
-                                              &hook.inode_u);
-                       if (WARN_ONCE(ret,
-                                     "error %i unpacking inode %llu",
-                                     ret, extent_iter.pos.inode)) {
-                               ret = -ENOENT;
-                               break;
+       do {
+               unsigned nr_pages, i, j;
+
+               nr_pages = pagevec_lookup_range(&pvec, inode->v.i_mapping,
+                                               &index, end_index);
+               for (i = 0; i < nr_pages; i++) {
+                       struct page *page = pvec.pages[i];
+                       u64 pg_start = page->index << PAGE_SECTORS_SHIFT;
+                       u64 pg_end = (page->index + 1) << PAGE_SECTORS_SHIFT;
+                       unsigned pg_offset = max(start, pg_start) - pg_start;
+                       unsigned pg_len = min(end, pg_end) - pg_offset - pg_start;
+                       struct bch_page_state *s;
+
+                       BUG_ON(end <= pg_start);
+                       BUG_ON(pg_offset >= PAGE_SECTORS);
+                       BUG_ON(pg_offset + pg_len > PAGE_SECTORS);
+
+                       lock_page(page);
+                       s = bch2_page_state(page);
+
+                       if (s) {
+                               spin_lock(&s->lock);
+                               for (j = pg_offset; j < pg_offset + pg_len; j++)
+                                       switch (s->s[j].state) {
+                                       case SECTOR_UNALLOCATED:
+                                               s->s[j].state = SECTOR_RESERVED;
+                                               break;
+                                       case SECTOR_DIRTY:
+                                               s->s[j].state = SECTOR_DIRTY_RESERVED;
+                                               i_sectors_delta--;
+                                               break;
+                                       default:
+                                               break;
+                                       }
+                               spin_unlock(&s->lock);
                        }
 
-                       ret = bch2_btree_insert_at(wop->c, &wop->res,
-                                       &hook.hook, op_journal_seq(wop),
-                                       BTREE_INSERT_NOFAIL|BTREE_INSERT_ATOMIC,
-                                       BTREE_INSERT_ENTRY(&extent_iter, k),
-                                       BTREE_INSERT_ENTRY_EXTRA_RES(&inode_iter,
-                                                       &hook.inode_p.inode.k_i, 2));
-               } else {
-                       ret = bch2_btree_insert_at(wop->c, &wop->res,
-                                       &hook.hook, op_journal_seq(wop),
-                                       BTREE_INSERT_NOFAIL|BTREE_INSERT_ATOMIC,
-                                       BTREE_INSERT_ENTRY(&extent_iter, k));
+                       unlock_page(page);
                }
+               pagevec_release(&pvec);
+       } while (index <= end_index);
 
-               BUG_ON(bkey_cmp(extent_iter.pos, bkey_start_pos(&k->k)));
-               BUG_ON(!ret != !k->k.size);
-err:
-               if (ret == -EINTR)
-                       continue;
-               if (ret)
-                       break;
+       i_sectors_acct(c, inode, NULL, i_sectors_delta);
+}
 
-               BUG_ON(bkey_cmp(extent_iter.pos, k->k.p) < 0);
-               bch2_keylist_pop_front(keys);
-       } while (!bch2_keylist_empty(keys));
+static inline unsigned inode_nr_replicas(struct bch_fs *c, struct bch_inode_info *inode)
+{
+       /* XXX: this should not be open coded */
+       return inode->ei_inode.bi_data_replicas
+               ? inode->ei_inode.bi_data_replicas - 1
+               : c->opts.data_replicas;
+}
 
-       bch2_btree_iter_unlock(&extent_iter);
-       bch2_btree_iter_unlock(&inode_iter);
+static inline unsigned sectors_to_reserve(struct bch_page_sector *s,
+                                                 unsigned nr_replicas)
+{
+       return max(0, (int) nr_replicas -
+                  s->nr_replicas -
+                  s->replicas_reserved);
+}
 
-       if (op->is_dio) {
-               struct dio_write *dio = container_of(op, struct dio_write, iop);
+static int bch2_get_page_disk_reservation(struct bch_fs *c,
+                               struct bch_inode_info *inode,
+                               struct page *page, bool check_enospc)
+{
+       struct bch_page_state *s = bch2_page_state_create(page, 0);
+       unsigned nr_replicas = inode_nr_replicas(c, inode);
+       struct disk_reservation disk_res = { 0 };
+       unsigned i, disk_res_sectors = 0;
+       int ret;
 
-               i_sectors_acct(wop->c, op->inode, &dio->quota_res,
-                              op->sectors_added - orig_sectors_added);
-       }
+       if (!s)
+               return -ENOMEM;
 
-       return ret;
+       for (i = 0; i < ARRAY_SIZE(s->s); i++)
+               disk_res_sectors += sectors_to_reserve(&s->s[i], nr_replicas);
+
+       if (!disk_res_sectors)
+               return 0;
+
+       ret = bch2_disk_reservation_get(c, &disk_res,
+                                       disk_res_sectors, 1,
+                                       !check_enospc
+                                       ? BCH_DISK_RESERVATION_NOFAIL
+                                       : 0);
+       if (unlikely(ret))
+               return ret;
+
+       for (i = 0; i < ARRAY_SIZE(s->s); i++)
+               s->s[i].replicas_reserved +=
+                       sectors_to_reserve(&s->s[i], nr_replicas);
+
+       return 0;
 }
 
-static inline void bch2_fswrite_op_init(struct bchfs_write_op *op,
-                                       struct bch_fs *c,
-                                       struct bch_inode_info *inode,
-                                       struct bch_io_opts opts,
-                                       bool is_dio)
+struct bch2_page_reservation {
+       struct disk_reservation disk;
+       struct quota_res        quota;
+};
+
+static void bch2_page_reservation_init(struct bch_fs *c,
+                       struct bch_inode_info *inode,
+                       struct bch2_page_reservation *res)
 {
-       op->inode               = inode;
-       op->sectors_added       = 0;
-       op->is_dio              = is_dio;
-       op->unalloc             = false;
-       op->new_i_size          = U64_MAX;
+       memset(res, 0, sizeof(*res));
 
-       bch2_write_op_init(&op->op, c);
-       op->op.csum_type        = bch2_data_checksum_type(c, opts.data_checksum);
-       op->op.compression_type = bch2_compression_opt_to_type(opts.compression);
-       op->op.devs             = c->fastest_devs;
-       op->op.index_update_fn  = bchfs_write_index_update;
-       op_journal_seq_set(&op->op, &inode->ei_journal_seq);
+       res->disk.nr_replicas = inode_nr_replicas(c, inode);
 }
 
-static inline struct bch_io_opts io_opts(struct bch_fs *c, struct bch_inode_info *inode)
+static void bch2_page_reservation_put(struct bch_fs *c,
+                       struct bch_inode_info *inode,
+                       struct bch2_page_reservation *res)
 {
-       struct bch_io_opts opts = bch2_opts_to_inode_opts(c->opts);
-
-       bch2_io_opts_apply(&opts, bch2_inode_opts_get(&inode->ei_inode));
-       return opts;
+       bch2_disk_reservation_put(c, &res->disk);
+       bch2_quota_reservation_put(c, inode, &res->quota);
 }
 
-/* page state: */
+static int bch2_page_reservation_get(struct bch_fs *c,
+                       struct bch_inode_info *inode, struct page *page,
+                       struct bch2_page_reservation *res,
+                       unsigned offset, unsigned len, bool check_enospc)
+{
+       struct bch_page_state *s = bch2_page_state_create(page, 0);
+       unsigned i, disk_sectors = 0, quota_sectors = 0;
+       int ret;
 
-/* stored in page->private: */
+       if (!s)
+               return -ENOMEM;
 
-/*
- * bch_page_state has to (unfortunately) be manipulated with cmpxchg - we could
- * almost protected it with the page lock, except that bch2_writepage_io_done has
- * to update the sector counts (and from interrupt/bottom half context).
- */
-struct bch_page_state {
-union { struct {
-       /* existing data: */
-       unsigned                sectors:PAGE_SECTOR_SHIFT + 1;
-       unsigned                nr_replicas:4;
-       unsigned                compressed:1;
+       BUG_ON(!s->uptodate);
+
+       for (i = round_down(offset, block_bytes(c)) >> 9;
+            i < round_up(offset + len, block_bytes(c)) >> 9;
+            i++) {
+               disk_sectors += sectors_to_reserve(&s->s[i],
+                                               res->disk.nr_replicas);
+               quota_sectors += s->s[i].state == SECTOR_UNALLOCATED;
+       }
 
-       /* Owns PAGE_SECTORS sized reservation: */
-       unsigned                reserved:1;
-       unsigned                reservation_replicas:4;
+       if (disk_sectors) {
+               ret = bch2_disk_reservation_add(c, &res->disk,
+                                               disk_sectors,
+                                               !check_enospc
+                                               ? BCH_DISK_RESERVATION_NOFAIL
+                                               : 0);
+               if (unlikely(ret))
+                       return ret;
+       }
 
-       /* Owns PAGE_SECTORS sized quota reservation: */
-       unsigned                quota_reserved:1;
+       if (quota_sectors) {
+               ret = bch2_quota_reservation_add(c, inode, &res->quota,
+                                                quota_sectors,
+                                                check_enospc);
+               if (unlikely(ret)) {
+                       struct disk_reservation tmp = {
+                               .sectors = disk_sectors
+                       };
 
-       /*
-        * Number of sectors on disk - for i_blocks
-        * Uncompressed size, not compressed size:
-        */
-       unsigned                dirty_sectors:PAGE_SECTOR_SHIFT + 1;
-};
-       /* for cmpxchg: */
-       unsigned long           v;
-};
-};
+                       bch2_disk_reservation_put(c, &tmp);
+                       res->disk.sectors -= disk_sectors;
+                       return ret;
+               }
+       }
 
-#define page_state_cmpxchg(_ptr, _new, _expr)                          \
-({                                                                     \
-       unsigned long _v = READ_ONCE((_ptr)->v);                        \
-       struct bch_page_state _old;                                     \
-                                                                       \
-       do {                                                            \
-               _old.v = _new.v = _v;                                   \
-               _expr;                                                  \
-                                                                       \
-               EBUG_ON(_new.sectors + _new.dirty_sectors > PAGE_SECTORS);\
-       } while (_old.v != _new.v &&                                    \
-                (_v = cmpxchg(&(_ptr)->v, _old.v, _new.v)) != _old.v); \
-                                                                       \
-       _old;                                                           \
-})
+       return 0;
+}
 
-static inline struct bch_page_state *page_state(struct page *page)
+static void bch2_clear_page_bits(struct page *page)
 {
-       struct bch_page_state *s = (void *) &page->private;
+       struct bch_inode_info *inode = to_bch_ei(page->mapping->host);
+       struct bch_fs *c = inode->v.i_sb->s_fs_info;
+       struct bch_page_state *s = bch2_page_state(page);
+       struct disk_reservation disk_res = { 0 };
+       int i, dirty_sectors = 0;
 
-       BUILD_BUG_ON(sizeof(*s) > sizeof(page->private));
+       if (!s)
+               return;
 
-       if (!PagePrivate(page))
-               SetPagePrivate(page);
+       EBUG_ON(!PageLocked(page));
+       EBUG_ON(PageWriteback(page));
 
-       return s;
-}
+       for (i = 0; i < ARRAY_SIZE(s->s); i++) {
+               disk_res.sectors += s->s[i].replicas_reserved;
+               s->s[i].replicas_reserved = 0;
 
-static inline unsigned page_res_sectors(struct bch_page_state s)
-{
+               switch (s->s[i].state) {
+               case SECTOR_DIRTY:
+                       s->s[i].state = SECTOR_UNALLOCATED;
+                       --dirty_sectors;
+                       break;
+               case SECTOR_DIRTY_RESERVED:
+                       s->s[i].state = SECTOR_RESERVED;
+                       break;
+               default:
+                       break;
+               }
+       }
 
-       return s.reserved ? s.reservation_replicas * PAGE_SECTORS : 0;
-}
+       bch2_disk_reservation_put(c, &disk_res);
 
-static void __bch2_put_page_reservation(struct bch_fs *c, struct bch_inode_info *inode,
-                                       struct bch_page_state s)
-{
-       struct disk_reservation res = { .sectors = page_res_sectors(s) };
-       struct quota_res quota_res = { .sectors = s.quota_reserved ? PAGE_SECTORS : 0 };
+       i_sectors_acct(c, inode, NULL, dirty_sectors);
 
-       bch2_quota_reservation_put(c, inode, &quota_res);
-       bch2_disk_reservation_put(c, &res);
+       bch2_page_state_release(page);
 }
 
-static void bch2_put_page_reservation(struct bch_fs *c, struct bch_inode_info *inode,
-                                     struct page *page)
+static void bch2_set_page_dirty(struct bch_fs *c,
+                       struct bch_inode_info *inode, struct page *page,
+                       struct bch2_page_reservation *res,
+                       unsigned offset, unsigned len)
 {
-       struct bch_page_state s;
+       struct bch_page_state *s = bch2_page_state(page);
+       unsigned i, dirty_sectors = 0;
 
-       s = page_state_cmpxchg(page_state(page), s, {
-               s.reserved              = 0;
-               s.quota_reserved        = 0;
-       });
+       WARN_ON((u64) page_offset(page) + offset + len >
+               round_up((u64) i_size_read(&inode->v), block_bytes(c)));
 
-       __bch2_put_page_reservation(c, inode, s);
-}
+       spin_lock(&s->lock);
 
-static int bch2_get_page_reservation(struct bch_fs *c, struct bch_inode_info *inode,
-                                    struct page *page, bool check_enospc)
-{
-       struct bch_page_state *s = page_state(page), new, old;
-       struct disk_reservation disk_res = bch2_disk_reservation_init(c,
-                                               READ_ONCE(c->opts.data_replicas));
-       struct quota_res quota_res = { 0 };
-       int ret = 0;
+       for (i = round_down(offset, block_bytes(c)) >> 9;
+            i < round_up(offset + len, block_bytes(c)) >> 9;
+            i++) {
+               unsigned sectors = sectors_to_reserve(&s->s[i],
+                                               res->disk.nr_replicas);
 
-       /*
-        * XXX: this could likely be quite a bit simpler, page reservations
-        * _should_ only be manipulated with page locked:
-        */
+               /*
+                * This can happen if we race with the error path in
+                * bch2_writepage_io_done():
+                */
+               sectors = min_t(unsigned, sectors, res->disk.sectors);
 
-       old = page_state_cmpxchg(s, new, {
-               if (new.reserved
-                   ? (new.reservation_replicas < disk_res.nr_replicas)
-                   : (new.sectors < PAGE_SECTORS ||
-                      new.nr_replicas < disk_res.nr_replicas ||
-                      new.compressed)) {
-                       int sectors = (disk_res.nr_replicas * PAGE_SECTORS -
-                                      page_res_sectors(new) -
-                                      disk_res.sectors);
-
-                       if (sectors > 0) {
-                               ret = bch2_disk_reservation_add(c, &disk_res, sectors,
-                                               !check_enospc
-                                               ? BCH_DISK_RESERVATION_NOFAIL : 0);
-                               if (unlikely(ret))
-                                       goto err;
-                       }
+               s->s[i].replicas_reserved += sectors;
+               res->disk.sectors -= sectors;
 
-                       new.reserved = 1;
-                       new.reservation_replicas = disk_res.nr_replicas;
+               switch (s->s[i].state) {
+               case SECTOR_UNALLOCATED:
+                       s->s[i].state = SECTOR_DIRTY;
+                       dirty_sectors++;
+                       break;
+               case SECTOR_RESERVED:
+                       s->s[i].state = SECTOR_DIRTY_RESERVED;
+                       break;
+               default:
+                       break;
                }
+       }
 
-               if (!new.quota_reserved &&
-                   new.sectors + new.dirty_sectors < PAGE_SECTORS) {
-                       ret = bch2_quota_reservation_add(c, inode, &quota_res,
-                                               PAGE_SECTORS - quota_res.sectors,
-                                               check_enospc);
-                       if (unlikely(ret))
-                               goto err;
+       spin_unlock(&s->lock);
 
-                       new.quota_reserved = 1;
-               }
-       });
+       i_sectors_acct(c, inode, &res->quota, dirty_sectors);
 
-       quota_res.sectors -= (new.quota_reserved - old.quota_reserved) * PAGE_SECTORS;
-       disk_res.sectors -= page_res_sectors(new) - page_res_sectors(old);
-err:
-       bch2_quota_reservation_put(c, inode, &quota_res);
-       bch2_disk_reservation_put(c, &disk_res);
-       return ret;
+       if (!PageDirty(page))
+               __set_page_dirty_nobuffers(page);
 }
 
-static void bch2_clear_page_bits(struct page *page)
+vm_fault_t bch2_page_fault(struct vm_fault *vmf)
 {
-       struct bch_inode_info *inode = to_bch_ei(page->mapping->host);
-       struct bch_fs *c = inode->v.i_sb->s_fs_info;
-       struct bch_page_state s;
+       struct file *file = vmf->vma->vm_file;
+       struct address_space *mapping = file->f_mapping;
+       struct address_space *fdm = faults_disabled_mapping();
+       struct bch_inode_info *inode = file_bch_inode(file);
+       int ret;
 
-       if (!PagePrivate(page))
-               return;
+       if (fdm == mapping)
+               return VM_FAULT_SIGBUS;
 
-       s = xchg(page_state(page), (struct bch_page_state) { .v = 0 });
-       ClearPagePrivate(page);
+       /* Lock ordering: */
+       if (fdm > mapping) {
+               struct bch_inode_info *fdm_host = to_bch_ei(fdm->host);
 
-       if (s.dirty_sectors)
-               i_sectors_acct(c, inode, NULL, -s.dirty_sectors);
+               if (bch2_pagecache_add_tryget(&inode->ei_pagecache_lock))
+                       goto got_lock;
 
-       __bch2_put_page_reservation(c, inode, s);
-}
+               bch2_pagecache_block_put(&fdm_host->ei_pagecache_lock);
 
-int bch2_set_page_dirty(struct page *page)
-{
-       struct bch_inode_info *inode = to_bch_ei(page->mapping->host);
-       struct bch_fs *c = inode->v.i_sb->s_fs_info;
-       struct quota_res quota_res = { 0 };
-       struct bch_page_state old, new;
+               bch2_pagecache_add_get(&inode->ei_pagecache_lock);
+               bch2_pagecache_add_put(&inode->ei_pagecache_lock);
 
-       old = page_state_cmpxchg(page_state(page), new,
-               new.dirty_sectors = PAGE_SECTORS - new.sectors;
-               new.quota_reserved = 0;
-       );
+               bch2_pagecache_block_get(&fdm_host->ei_pagecache_lock);
 
-       quota_res.sectors += old.quota_reserved * PAGE_SECTORS;
+               /* Signal that lock has been dropped: */
+               set_fdm_dropped_locks();
+               return VM_FAULT_SIGBUS;
+       }
 
-       if (old.dirty_sectors != new.dirty_sectors)
-               i_sectors_acct(c, inode, &quota_res,
-                              new.dirty_sectors - old.dirty_sectors);
-       bch2_quota_reservation_put(c, inode, &quota_res);
+       bch2_pagecache_add_get(&inode->ei_pagecache_lock);
+got_lock:
+       ret = filemap_fault(vmf);
+       bch2_pagecache_add_put(&inode->ei_pagecache_lock);
 
-       return __set_page_dirty_nobuffers(page);
+       return ret;
 }
 
-int bch2_page_mkwrite(struct vm_fault *vmf)
+vm_fault_t bch2_page_mkwrite(struct vm_fault *vmf)
 {
        struct page *page = vmf->page;
        struct file *file = vmf->vma->vm_file;
        struct bch_inode_info *inode = file_bch_inode(file);
-       struct address_space *mapping = inode->v.i_mapping;
+       struct address_space *mapping = file->f_mapping;
        struct bch_fs *c = inode->v.i_sb->s_fs_info;
-       int ret = VM_FAULT_LOCKED;
+       struct bch2_page_reservation res;
+       unsigned len;
+       loff_t isize;
+       int ret;
+
+       bch2_page_reservation_init(c, inode, &res);
 
        sb_start_pagefault(inode->v.i_sb);
        file_update_time(file);
@@ -725,39 +800,48 @@ int bch2_page_mkwrite(struct vm_fault *vmf)
         * a write_invalidate_inode_pages_range() that works without dropping
         * page lock before invalidating page
         */
-       if (current->pagecache_lock != &mapping->add_lock)
-               pagecache_add_get(&mapping->add_lock);
+       bch2_pagecache_add_get(&inode->ei_pagecache_lock);
 
        lock_page(page);
-       if (page->mapping != mapping ||
-           page_offset(page) > i_size_read(&inode->v)) {
+       isize = i_size_read(&inode->v);
+
+       if (page->mapping != mapping || page_offset(page) >= isize) {
                unlock_page(page);
                ret = VM_FAULT_NOPAGE;
                goto out;
        }
 
-       if (bch2_get_page_reservation(c, inode, page, true)) {
+       len = min_t(loff_t, PAGE_SIZE, isize - page_offset(page));
+
+       if (!bch2_page_state_create(page, __GFP_NOFAIL)->uptodate) {
+               if (bch2_page_state_set(c, inode_inum(inode), &page, 1)) {
+                       unlock_page(page);
+                       ret = VM_FAULT_SIGBUS;
+                       goto out;
+               }
+       }
+
+       if (bch2_page_reservation_get(c, inode, page, &res, 0, len, true)) {
                unlock_page(page);
                ret = VM_FAULT_SIGBUS;
                goto out;
        }
 
-       if (!PageDirty(page))
-               set_page_dirty(page);
+       bch2_set_page_dirty(c, inode, page, &res, 0, len);
+       bch2_page_reservation_put(c, inode, &res);
+
        wait_for_stable_page(page);
+       ret = VM_FAULT_LOCKED;
 out:
-       if (current->pagecache_lock != &mapping->add_lock)
-               pagecache_add_put(&mapping->add_lock);
+       bch2_pagecache_add_put(&inode->ei_pagecache_lock);
        sb_end_pagefault(inode->v.i_sb);
+
        return ret;
 }
 
 void bch2_invalidatepage(struct page *page, unsigned int offset,
                         unsigned int length)
 {
-       EBUG_ON(!PageLocked(page));
-       EBUG_ON(PageWriteback(page));
-
        if (offset || length < PAGE_SIZE)
                return;
 
@@ -766,9 +850,6 @@ void bch2_invalidatepage(struct page *page, unsigned int offset,
 
 int bch2_releasepage(struct page *page, gfp_t gfp_mask)
 {
-       EBUG_ON(!PageLocked(page));
-       EBUG_ON(PageWriteback(page));
-
        if (PageDirty(page))
                return 0;
 
@@ -782,65 +863,33 @@ int bch2_migrate_page(struct address_space *mapping, struct page *newpage,
 {
        int ret;
 
-       ret = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0);
+       EBUG_ON(!PageLocked(page));
+       EBUG_ON(!PageLocked(newpage));
+
+       ret = migrate_page_move_mapping(mapping, newpage, page, 0);
        if (ret != MIGRATEPAGE_SUCCESS)
                return ret;
 
-       if (PagePrivate(page)) {
-               *page_state(newpage) = *page_state(page);
-               ClearPagePrivate(page);
-       }
+       if (PagePrivate(page))
+               attach_page_private(newpage, detach_page_private(page));
 
-       migrate_page_copy(newpage, page);
+       if (mode != MIGRATE_SYNC_NO_COPY)
+               migrate_page_copy(newpage, page);
+       else
+               migrate_page_states(newpage, page);
        return MIGRATEPAGE_SUCCESS;
 }
 #endif
 
-/* readpages/writepages: */
+/* readpage(s): */
 
-static bool bio_can_add_page_contig(struct bio *bio, struct page *page)
+static void bch2_readpages_end_io(struct bio *bio)
 {
-       sector_t offset = (sector_t) page->index << PAGE_SECTOR_SHIFT;
-
-       return bio->bi_vcnt < bio->bi_max_vecs &&
-               bio_end_sector(bio) == offset;
-}
+       struct bvec_iter_all iter;
+       struct bio_vec *bv;
 
-static void __bio_add_page(struct bio *bio, struct page *page)
-{
-       bio->bi_io_vec[bio->bi_vcnt++] = (struct bio_vec) {
-               .bv_page = page,
-               .bv_len = PAGE_SIZE,
-               .bv_offset = 0,
-       };
-
-       bio->bi_iter.bi_size += PAGE_SIZE;
-}
-
-static int bio_add_page_contig(struct bio *bio, struct page *page)
-{
-       sector_t offset = (sector_t) page->index << PAGE_SECTOR_SHIFT;
-
-       EBUG_ON(!bio->bi_max_vecs);
-
-       if (!bio->bi_vcnt)
-               bio->bi_iter.bi_sector = offset;
-       else if (!bio_can_add_page_contig(bio, page))
-               return -1;
-
-       __bio_add_page(bio, page);
-       return 0;
-}
-
-/* readpage(s): */
-
-static void bch2_readpages_end_io(struct bio *bio)
-{
-       struct bio_vec *bv;
-       int i;
-
-       bio_for_each_segment_all(bv, bio, i) {
-               struct page *page = bv->bv_page;
+       bio_for_each_segment_all(bv, bio, iter) {
+               struct page *page = bv->bv_page;
 
                if (!bio->bi_status) {
                        SetPageUptodate(page);
@@ -856,272 +905,285 @@ static void bch2_readpages_end_io(struct bio *bio)
 
 struct readpages_iter {
        struct address_space    *mapping;
-       struct list_head        pages;
+       struct page             **pages;
        unsigned                nr_pages;
+       unsigned                idx;
+       pgoff_t                 offset;
 };
 
-static inline void page_state_init_for_read(struct page *page)
+static int readpages_iter_init(struct readpages_iter *iter,
+                              struct readahead_control *ractl)
 {
-       struct bch_page_state *s = page_state(page);
+       unsigned i, nr_pages = readahead_count(ractl);
 
-       BUG_ON(s->reserved);
-       s->sectors      = 0;
-       s->compressed   = 0;
-}
+       memset(iter, 0, sizeof(*iter));
 
-static int readpage_add_page(struct readpages_iter *iter, struct page *page)
-{
-       int ret;
+       iter->mapping   = ractl->mapping;
+       iter->offset    = readahead_index(ractl);
+       iter->nr_pages  = nr_pages;
+
+       iter->pages = kmalloc_array(nr_pages, sizeof(struct page *), GFP_NOFS);
+       if (!iter->pages)
+               return -ENOMEM;
 
-       prefetchw(&page->flags);
-       page_state_init_for_read(page);
+       nr_pages = __readahead_batch(ractl, iter->pages, nr_pages);
+       for (i = 0; i < nr_pages; i++) {
+               __bch2_page_state_create(iter->pages[i], __GFP_NOFAIL);
+               put_page(iter->pages[i]);
+       }
 
-       ret = add_to_page_cache_lru(page, iter->mapping,
-                                   page->index, GFP_NOFS);
-       put_page(page);
-       return ret;
+       return 0;
 }
 
 static inline struct page *readpage_iter_next(struct readpages_iter *iter)
 {
-       while (iter->nr_pages) {
-               struct page *page =
-                       list_last_entry(&iter->pages, struct page, lru);
-
-               prefetchw(&page->flags);
-               list_del(&page->lru);
-               iter->nr_pages--;
+       if (iter->idx >= iter->nr_pages)
+               return NULL;
 
-               if (!readpage_add_page(iter, page))
-                       return page;
-       }
+       EBUG_ON(iter->pages[iter->idx]->index != iter->offset + iter->idx);
 
-       return NULL;
+       return iter->pages[iter->idx];
 }
 
-#define for_each_readpage_page(_iter, _page)                           \
-       for (;                                                          \
-            ((_page) = __readpage_next_page(&(_iter)));)               \
-
-static void bch2_add_page_sectors(struct bio *bio, struct bkey_s_c k)
+static bool extent_partial_reads_expensive(struct bkey_s_c k)
 {
-       struct bvec_iter iter;
-       struct bio_vec bv;
-       bool compressed = bch2_extent_is_compressed(k);
-       unsigned nr_ptrs = bch2_extent_nr_dirty_ptrs(k);
-
-       bio_for_each_segment(bv, bio, iter) {
-               struct bch_page_state *s = page_state(bv.bv_page);
-
-               /* sectors in @k from the start of this page: */
-               unsigned k_sectors = k.k->size - (iter.bi_sector - k.k->p.offset);
+       struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
+       struct bch_extent_crc_unpacked crc;
+       const union bch_extent_entry *i;
 
-               unsigned page_sectors = min(bv.bv_len >> 9, k_sectors);
-
-               s->nr_replicas = !s->sectors
-                       ? nr_ptrs
-                       : min_t(unsigned, s->nr_replicas, nr_ptrs);
-
-               BUG_ON(s->sectors + page_sectors > PAGE_SECTORS);
-               s->sectors += page_sectors;
-
-               s->compressed |= compressed;
-       }
+       bkey_for_each_crc(k.k, ptrs, crc, i)
+               if (crc.csum_type || crc.compression_type)
+                       return true;
+       return false;
 }
 
 static void readpage_bio_extend(struct readpages_iter *iter,
-                               struct bio *bio, u64 offset,
+                               struct bio *bio,
+                               unsigned sectors_this_extent,
                                bool get_more)
 {
-       struct page *page;
-       pgoff_t page_offset;
-       int ret;
-
-       while (bio_end_sector(bio) < offset &&
+       while (bio_sectors(bio) < sectors_this_extent &&
               bio->bi_vcnt < bio->bi_max_vecs) {
-               page_offset = bio_end_sector(bio) >> PAGE_SECTOR_SHIFT;
+               pgoff_t page_offset = bio_end_sector(bio) >> PAGE_SECTORS_SHIFT;
+               struct page *page = readpage_iter_next(iter);
+               int ret;
 
-               if (iter->nr_pages) {
-                       page = list_last_entry(&iter->pages, struct page, lru);
-                       if (page->index != page_offset)
+               if (page) {
+                       if (iter->offset + iter->idx != page_offset)
                                break;
 
-                       list_del(&page->lru);
-                       iter->nr_pages--;
-               } else if (get_more) {
-                       rcu_read_lock();
-                       page = radix_tree_lookup(&iter->mapping->page_tree, page_offset);
-                       rcu_read_unlock();
+                       iter->idx++;
+               } else {
+                       if (!get_more)
+                               break;
 
-                       if (page && !radix_tree_exceptional_entry(page))
+                       page = xa_load(&iter->mapping->i_pages, page_offset);
+                       if (page && !xa_is_value(page))
                                break;
 
                        page = __page_cache_alloc(readahead_gfp_mask(iter->mapping));
                        if (!page)
                                break;
 
-                       page->index = page_offset;
-                       ClearPageReadahead(bio->bi_io_vec[bio->bi_vcnt - 1].bv_page);
-               } else {
-                       break;
-               }
+                       if (!__bch2_page_state_create(page, 0)) {
+                               put_page(page);
+                               break;
+                       }
 
-               ret = readpage_add_page(iter, page);
-               if (ret)
-                       break;
+                       ret = add_to_page_cache_lru(page, iter->mapping,
+                                                   page_offset, GFP_NOFS);
+                       if (ret) {
+                               __bch2_page_state_release(page);
+                               put_page(page);
+                               break;
+                       }
 
-               __bio_add_page(bio, page);
-       }
+                       put_page(page);
+               }
 
-       if (!iter->nr_pages)
-               SetPageReadahead(bio->bi_io_vec[bio->bi_vcnt - 1].bv_page);
+               BUG_ON(!bio_add_page(bio, page, PAGE_SIZE, 0));
+       }
 }
 
-static void bchfs_read(struct bch_fs *c, struct btree_iter *iter,
-                      struct bch_read_bio *rbio, u64 inum,
+static void bchfs_read(struct btree_trans *trans,
+                      struct bch_read_bio *rbio,
+                      subvol_inum inum,
                       struct readpages_iter *readpages_iter)
 {
-       struct bio *bio = &rbio->bio;
+       struct bch_fs *c = trans->c;
+       struct btree_iter iter;
+       struct bkey_buf sk;
        int flags = BCH_READ_RETRY_IF_STALE|
                BCH_READ_MAY_PROMOTE;
+       u32 snapshot;
+       int ret = 0;
+
+       rbio->c = c;
+       rbio->start_time = local_clock();
+       rbio->subvol = inum.subvol;
+
+       bch2_bkey_buf_init(&sk);
+retry:
+       bch2_trans_begin(trans);
+       iter = (struct btree_iter) { NULL };
 
+       ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
+       if (ret)
+               goto err;
+
+       bch2_trans_iter_init(trans, &iter, BTREE_ID_extents,
+                            SPOS(inum.inum, rbio->bio.bi_iter.bi_sector, snapshot),
+                            BTREE_ITER_SLOTS);
        while (1) {
-               struct extent_pick_ptr pick;
-               BKEY_PADDED(k) tmp;
                struct bkey_s_c k;
-               unsigned bytes;
-               bool is_last;
+               unsigned bytes, sectors, offset_into_extent;
+               enum btree_id data_btree = BTREE_ID_extents;
+
+               /*
+                * read_extent -> io_time_reset may cause a transaction restart
+                * without returning an error, we need to check for that here:
+                */
+               if (!bch2_trans_relock(trans)) {
+                       ret = -EINTR;
+                       break;
+               }
 
-               bch2_btree_iter_set_pos(iter, POS(inum, bio->bi_iter.bi_sector));
+               bch2_btree_iter_set_pos(&iter,
+                               POS(inum.inum, rbio->bio.bi_iter.bi_sector));
 
-               k = bch2_btree_iter_peek_with_holes(iter);
-               BUG_ON(!k.k);
+               k = bch2_btree_iter_peek_slot(&iter);
+               ret = bkey_err(k);
+               if (ret)
+                       break;
 
-               if (IS_ERR(k.k)) {
-                       int ret = bch2_btree_iter_unlock(iter);
-                       BUG_ON(!ret);
-                       bcache_io_error(c, bio, "btree IO error %i", ret);
-                       bio_endio(bio);
-                       return;
-               }
+               offset_into_extent = iter.pos.offset -
+                       bkey_start_offset(k.k);
+               sectors = k.k->size - offset_into_extent;
 
-               bkey_reassemble(&tmp.k, k);
-               bch2_btree_iter_unlock(iter);
-               k = bkey_i_to_s_c(&tmp.k);
+               bch2_bkey_buf_reassemble(&sk, c, k);
 
-               bch2_extent_pick_ptr(c, k, NULL, &pick);
-               if (IS_ERR(pick.ca)) {
-                       bcache_io_error(c, bio, "no device to read from");
-                       bio_endio(bio);
-                       return;
-               }
+               ret = bch2_read_indirect_extent(trans, &data_btree,
+                                       &offset_into_extent, &sk);
+               if (ret)
+                       break;
+
+               k = bkey_i_to_s_c(sk.k);
+
+               sectors = min(sectors, k.k->size - offset_into_extent);
 
                if (readpages_iter)
-                       readpage_bio_extend(readpages_iter,
-                                           bio, k.k->p.offset,
-                                           pick.ca &&
-                                           (pick.crc.csum_type ||
-                                            pick.crc.compression_type));
-
-               bytes = (min_t(u64, k.k->p.offset, bio_end_sector(bio)) -
-                        bio->bi_iter.bi_sector) << 9;
-               is_last = bytes == bio->bi_iter.bi_size;
-               swap(bio->bi_iter.bi_size, bytes);
-
-               if (bkey_extent_is_allocation(k.k))
-                       bch2_add_page_sectors(bio, k);
-
-               if (pick.ca) {
-                       if (!is_last) {
-                               bio_inc_remaining(&rbio->bio);
-                               flags |= BCH_READ_MUST_CLONE;
-                               trace_read_split(&rbio->bio);
-                       }
+                       readpage_bio_extend(readpages_iter, &rbio->bio, sectors,
+                                           extent_partial_reads_expensive(k));
 
-                       bch2_read_extent(c, rbio, bkey_s_c_to_extent(k),
-                                        &pick, flags);
-               } else {
-                       zero_fill_bio(bio);
+               bytes = min(sectors, bio_sectors(&rbio->bio)) << 9;
+               swap(rbio->bio.bi_iter.bi_size, bytes);
 
-                       if (is_last)
-                               bio_endio(bio);
-               }
+               if (rbio->bio.bi_iter.bi_size == bytes)
+                       flags |= BCH_READ_LAST_FRAGMENT;
+
+               bch2_bio_page_state_set(&rbio->bio, k);
+
+               bch2_read_extent(trans, rbio, iter.pos,
+                                data_btree, k, offset_into_extent, flags);
+
+               if (flags & BCH_READ_LAST_FRAGMENT)
+                       break;
+
+               swap(rbio->bio.bi_iter.bi_size, bytes);
+               bio_advance(&rbio->bio, bytes);
+
+               ret = btree_trans_too_many_iters(trans);
+               if (ret)
+                       break;
+       }
+err:
+       bch2_trans_iter_exit(trans, &iter);
 
-               if (is_last)
-                       return;
+       if (ret == -EINTR)
+               goto retry;
 
-               swap(bio->bi_iter.bi_size, bytes);
-               bio_advance(bio, bytes);
+       if (ret) {
+               bch_err_inum_ratelimited(c, inum.inum,
+                               "read error %i from btree lookup", ret);
+               rbio->bio.bi_status = BLK_STS_IOERR;
+               bio_endio(&rbio->bio);
        }
+
+       bch2_bkey_buf_exit(&sk, c);
 }
 
-int bch2_readpages(struct file *file, struct address_space *mapping,
-                  struct list_head *pages, unsigned nr_pages)
+void bch2_readahead(struct readahead_control *ractl)
 {
-       struct bch_inode_info *inode = to_bch_ei(mapping->host);
+       struct bch_inode_info *inode = to_bch_ei(ractl->mapping->host);
        struct bch_fs *c = inode->v.i_sb->s_fs_info;
-       struct bch_io_opts opts = io_opts(c, inode);
-       struct btree_iter iter;
+       struct bch_io_opts opts = io_opts(c, &inode->ei_inode);
+       struct btree_trans trans;
        struct page *page;
-       struct readpages_iter readpages_iter = {
-               .mapping = mapping, .nr_pages = nr_pages
-       };
+       struct readpages_iter readpages_iter;
+       int ret;
 
-       bch2_btree_iter_init(&iter, c, BTREE_ID_EXTENTS, POS_MIN, 0);
+       ret = readpages_iter_init(&readpages_iter, ractl);
+       BUG_ON(ret);
 
-       INIT_LIST_HEAD(&readpages_iter.pages);
-       list_add(&readpages_iter.pages, pages);
-       list_del_init(pages);
+       bch2_trans_init(&trans, c, 0, 0);
 
-       if (current->pagecache_lock != &mapping->add_lock)
-               pagecache_add_get(&mapping->add_lock);
+       bch2_pagecache_add_get(&inode->ei_pagecache_lock);
 
        while ((page = readpage_iter_next(&readpages_iter))) {
-               unsigned n = max_t(unsigned,
-                                  min_t(unsigned, readpages_iter.nr_pages + 1,
-                                        BIO_MAX_PAGES),
-                                  c->sb.encoded_extent_max >> PAGE_SECTOR_SHIFT);
-
+               pgoff_t index = readpages_iter.offset + readpages_iter.idx;
+               unsigned n = min_t(unsigned,
+                                  readpages_iter.nr_pages -
+                                  readpages_iter.idx,
+                                  BIO_MAX_VECS);
                struct bch_read_bio *rbio =
                        rbio_init(bio_alloc_bioset(GFP_NOFS, n, &c->bio_read),
                                  opts);
 
+               readpages_iter.idx++;
+
+               bio_set_op_attrs(&rbio->bio, REQ_OP_READ, 0);
+               rbio->bio.bi_iter.bi_sector = (sector_t) index << PAGE_SECTORS_SHIFT;
                rbio->bio.bi_end_io = bch2_readpages_end_io;
-               bio_add_page_contig(&rbio->bio, page);
-               bchfs_read(c, &iter, rbio, inode->v.i_ino, &readpages_iter);
+               BUG_ON(!bio_add_page(&rbio->bio, page, PAGE_SIZE, 0));
+
+               bchfs_read(&trans, rbio, inode_inum(inode),
+                          &readpages_iter);
        }
 
-       if (current->pagecache_lock != &mapping->add_lock)
-               pagecache_add_put(&mapping->add_lock);
+       bch2_pagecache_add_put(&inode->ei_pagecache_lock);
 
-       return 0;
+       bch2_trans_exit(&trans);
+       kfree(readpages_iter.pages);
 }
 
 static void __bchfs_readpage(struct bch_fs *c, struct bch_read_bio *rbio,
-                            u64 inum, struct page *page)
+                            subvol_inum inum, struct page *page)
 {
-       struct btree_iter iter;
+       struct btree_trans trans;
 
-       page_state_init_for_read(page);
+       bch2_page_state_create(page, __GFP_NOFAIL);
 
        bio_set_op_attrs(&rbio->bio, REQ_OP_READ, REQ_SYNC);
-       bio_add_page_contig(&rbio->bio, page);
+       rbio->bio.bi_iter.bi_sector =
+               (sector_t) page->index << PAGE_SECTORS_SHIFT;
+       BUG_ON(!bio_add_page(&rbio->bio, page, PAGE_SIZE, 0));
 
-       bch2_btree_iter_init(&iter, c, BTREE_ID_EXTENTS, POS_MIN, 0);
-       bchfs_read(c, &iter, rbio, inum, NULL);
+       bch2_trans_init(&trans, c, 0, 0);
+       bchfs_read(&trans, rbio, inum, NULL);
+       bch2_trans_exit(&trans);
 }
 
 int bch2_readpage(struct file *file, struct page *page)
 {
        struct bch_inode_info *inode = to_bch_ei(page->mapping->host);
        struct bch_fs *c = inode->v.i_sb->s_fs_info;
-       struct bch_io_opts opts = io_opts(c, inode);
+       struct bch_io_opts opts = io_opts(c, &inode->ei_inode);
        struct bch_read_bio *rbio;
 
        rbio = rbio_init(bio_alloc_bioset(GFP_NOFS, 1, &c->bio_read), opts);
        rbio->bio.bi_end_io = bch2_readpages_end_io;
 
-       __bchfs_readpage(c, rbio, inode->v.i_ino, page);
+       __bchfs_readpage(c, rbio, inode_inum(inode), page);
        return 0;
 }
 
@@ -1140,11 +1202,11 @@ static int bch2_read_single_page(struct page *page,
        DECLARE_COMPLETION_ONSTACK(done);
 
        rbio = rbio_init(bio_alloc_bioset(GFP_NOFS, 1, &c->bio_read),
-                        io_opts(c, inode));
+                        io_opts(c, &inode->ei_inode));
        rbio->bio.bi_private = &done;
        rbio->bio.bi_end_io = bch2_read_single_page_end_io;
 
-       __bchfs_readpage(c, rbio, inode->v.i_ino, page);
+       __bchfs_readpage(c, rbio, inode_inum(inode), page);
        wait_for_completion(&done);
 
        ret = blk_status_to_errno(rbio->bio.bi_status);
@@ -1167,7 +1229,9 @@ struct bch_writepage_state {
 static inline struct bch_writepage_state bch_writepage_state_init(struct bch_fs *c,
                                                                  struct bch_inode_info *inode)
 {
-       return (struct bch_writepage_state) { .opts = io_opts(c, inode) };
+       return (struct bch_writepage_state) {
+               .opts = io_opts(c, &inode->ei_inode)
+       };
 }
 
 static void bch2_writepage_io_free(struct closure *cl)
@@ -1175,50 +1239,75 @@ static void bch2_writepage_io_free(struct closure *cl)
        struct bch_writepage_io *io = container_of(cl,
                                        struct bch_writepage_io, cl);
 
-       bio_put(&io->op.op.wbio.bio);
+       bio_put(&io->op.wbio.bio);
 }
 
 static void bch2_writepage_io_done(struct closure *cl)
 {
        struct bch_writepage_io *io = container_of(cl,
                                        struct bch_writepage_io, cl);
-       struct bch_fs *c = io->op.op.c;
-       struct bio *bio = &io->op.op.wbio.bio;
+       struct bch_fs *c = io->op.c;
+       struct bio *bio = &io->op.wbio.bio;
+       struct bvec_iter_all iter;
        struct bio_vec *bvec;
        unsigned i;
 
-       atomic_sub(bio->bi_vcnt, &c->writeback_pages);
-       wake_up(&c->writeback_wait);
+       up(&io->op.c->io_in_flight);
+
+       if (io->op.error) {
+               set_bit(EI_INODE_ERROR, &io->inode->ei_flags);
+
+               bio_for_each_segment_all(bvec, bio, iter) {
+                       struct bch_page_state *s;
 
-       if (io->op.op.error) {
-               bio_for_each_segment_all(bvec, bio, i)
                        SetPageError(bvec->bv_page);
-               set_bit(AS_EIO, &io->op.inode->v.i_mapping->flags);
+                       mapping_set_error(bvec->bv_page->mapping, -EIO);
+
+                       s = __bch2_page_state(bvec->bv_page);
+                       spin_lock(&s->lock);
+                       for (i = 0; i < PAGE_SECTORS; i++)
+                               s->s[i].nr_replicas = 0;
+                       spin_unlock(&s->lock);
+               }
+       }
+
+       if (io->op.flags & BCH_WRITE_WROTE_DATA_INLINE) {
+               bio_for_each_segment_all(bvec, bio, iter) {
+                       struct bch_page_state *s;
+
+                       s = __bch2_page_state(bvec->bv_page);
+                       spin_lock(&s->lock);
+                       for (i = 0; i < PAGE_SECTORS; i++)
+                               s->s[i].nr_replicas = 0;
+                       spin_unlock(&s->lock);
+               }
        }
 
        /*
         * racing with fallocate can cause us to add fewer sectors than
         * expected - but we shouldn't add more sectors than expected:
         */
-       BUG_ON(io->op.sectors_added > (s64) io->new_sectors);
+       WARN_ON(io->op.i_sectors_delta > 0);
 
        /*
         * (error (due to going RO) halfway through a page can screw that up
         * slightly)
         * XXX wtf?
-          BUG_ON(io->op.sectors_added - io->new_sectors >= (s64) PAGE_SECTORS);
+          BUG_ON(io->op.op.i_sectors_delta >= PAGE_SECTORS);
         */
 
        /*
         * PageWriteback is effectively our ref on the inode - fixup i_blocks
         * before calling end_page_writeback:
         */
-       if (io->op.sectors_added != io->new_sectors)
-               i_sectors_acct(c, io->op.inode, NULL,
-                              io->op.sectors_added - (s64) io->new_sectors);
+       i_sectors_acct(c, io->inode, NULL, io->op.i_sectors_delta);
+
+       bio_for_each_segment_all(bvec, bio, iter) {
+               struct bch_page_state *s = __bch2_page_state(bvec->bv_page);
 
-       bio_for_each_segment_all(bvec, bio, i)
-               end_page_writeback(bvec->bv_page);
+               if (atomic_dec_and_test(&s->write_count))
+                       end_page_writeback(bvec->bv_page);
+       }
 
        closure_return_with_destructor(&io->cl, bch2_writepage_io_free);
 }
@@ -1226,12 +1315,11 @@ static void bch2_writepage_io_done(struct closure *cl)
 static void bch2_writepage_do_io(struct bch_writepage_state *w)
 {
        struct bch_writepage_io *io = w->io;
-       struct bio *bio = &io->op.op.wbio.bio;
 
-       w->io = NULL;
-       atomic_add(bio->bi_vcnt, &io->op.op.c->writeback_pages);
+       down(&io->op.c->io_in_flight);
 
-       closure_call(&io->op.op.cl, bch2_write, NULL, &io->cl);
+       w->io = NULL;
+       closure_call(&io->op.cl, bch2_write, NULL, &io->cl);
        continue_at(&io->cl, bch2_writepage_io_done, NULL);
 }
 
@@ -1240,39 +1328,45 @@ static void bch2_writepage_do_io(struct bch_writepage_state *w)
  * possible, else allocating a new one:
  */
 static void bch2_writepage_io_alloc(struct bch_fs *c,
+                                   struct writeback_control *wbc,
                                    struct bch_writepage_state *w,
                                    struct bch_inode_info *inode,
-                                   struct page *page,
+                                   u64 sector,
                                    unsigned nr_replicas)
 {
        struct bch_write_op *op;
-       u64 offset = (u64) page->index << PAGE_SECTOR_SHIFT;
 
-       w->io = container_of(bio_alloc_bioset(GFP_NOFS,
-                                             BIO_MAX_PAGES,
+       w->io = container_of(bio_alloc_bioset(GFP_NOFS, BIO_MAX_VECS,
                                              &c->writepage_bioset),
-                            struct bch_writepage_io, op.op.wbio.bio);
+                            struct bch_writepage_io, op.wbio.bio);
 
        closure_init(&w->io->cl, NULL);
-       w->io->new_sectors      = 0;
-       bch2_fswrite_op_init(&w->io->op, c, inode, w->opts, false);
-       op                      = &w->io->op.op;
+       w->io->inode            = inode;
+
+       op                      = &w->io->op;
+       bch2_write_op_init(op, c, w->opts);
+       op->target              = w->opts.foreground_target;
        op->nr_replicas         = nr_replicas;
        op->res.nr_replicas     = nr_replicas;
        op->write_point         = writepoint_hashed(inode->ei_last_dirtied);
-       op->pos                 = POS(inode->v.i_ino, offset);
-       op->wbio.bio.bi_iter.bi_sector = offset;
+       op->subvol              = inode->ei_subvol;
+       op->pos                 = POS(inode->v.i_ino, sector);
+       op->wbio.bio.bi_iter.bi_sector = sector;
+       op->wbio.bio.bi_opf     = wbc_to_write_flags(wbc);
 }
 
-static int __bch2_writepage(struct bch_fs *c, struct page *page,
+static int __bch2_writepage(struct page *page,
                            struct writeback_control *wbc,
-                           struct bch_writepage_state *w)
+                           void *data)
 {
        struct bch_inode_info *inode = to_bch_ei(page->mapping->host);
-       struct bch_page_state new, old;
-       unsigned offset;
+       struct bch_fs *c = inode->v.i_sb->s_fs_info;
+       struct bch_writepage_state *w = data;
+       struct bch_page_state *s, orig;
+       unsigned i, offset, nr_replicas_this_write = U32_MAX;
        loff_t i_size = i_size_read(&inode->v);
        pgoff_t end_index = i_size >> PAGE_SHIFT;
+       int ret;
 
        EBUG_ON(!PageUptodate(page));
 
@@ -1296,197 +1390,118 @@ static int __bch2_writepage(struct bch_fs *c, struct page *page,
         */
        zero_user_segment(page, offset, PAGE_SIZE);
 do_io:
-       /* Before unlocking the page, transfer reservation to w->io: */
-       old = page_state_cmpxchg(page_state(page), new, {
-               EBUG_ON(!new.reserved &&
-                       (new.sectors != PAGE_SECTORS ||
-                       new.compressed));
+       s = bch2_page_state_create(page, __GFP_NOFAIL);
 
-               if (new.reserved)
-                       new.nr_replicas = new.reservation_replicas;
-               new.reserved = 0;
-
-               new.compressed |= w->opts.compression != 0;
-
-               new.sectors += new.dirty_sectors;
-               new.dirty_sectors = 0;
-       });
+       /*
+        * Things get really hairy with errors during writeback:
+        */
+       ret = bch2_get_page_disk_reservation(c, inode, page, false);
+       BUG_ON(ret);
 
-       if (w->io &&
-           (w->io->op.op.res.nr_replicas != new.nr_replicas ||
-            !bio_can_add_page_contig(&w->io->op.op.wbio.bio, page)))
-               bch2_writepage_do_io(w);
+       /* Before unlocking the page, get copy of reservations: */
+       spin_lock(&s->lock);
+       orig = *s;
+       spin_unlock(&s->lock);
 
-       if (!w->io)
-               bch2_writepage_io_alloc(c, w, inode, page, new.nr_replicas);
+       for (i = 0; i < PAGE_SECTORS; i++) {
+               if (s->s[i].state < SECTOR_DIRTY)
+                       continue;
 
-       w->io->new_sectors += new.sectors - old.sectors;
+               nr_replicas_this_write =
+                       min_t(unsigned, nr_replicas_this_write,
+                             s->s[i].nr_replicas +
+                             s->s[i].replicas_reserved);
+       }
 
-       BUG_ON(inode != w->io->op.inode);
-       BUG_ON(bio_add_page_contig(&w->io->op.op.wbio.bio, page));
+       for (i = 0; i < PAGE_SECTORS; i++) {
+               if (s->s[i].state < SECTOR_DIRTY)
+                       continue;
 
-       if (old.reserved)
-               w->io->op.op.res.sectors += old.reservation_replicas * PAGE_SECTORS;
+               s->s[i].nr_replicas = w->opts.compression
+                       ? 0 : nr_replicas_this_write;
 
-       /* while page is locked: */
-       w->io->op.new_i_size = i_size;
+               s->s[i].replicas_reserved = 0;
+               s->s[i].state = SECTOR_ALLOCATED;
+       }
 
-       if (wbc->sync_mode == WB_SYNC_ALL)
-               w->io->op.op.wbio.bio.bi_opf |= REQ_SYNC;
+       BUG_ON(atomic_read(&s->write_count));
+       atomic_set(&s->write_count, 1);
 
        BUG_ON(PageWriteback(page));
        set_page_writeback(page);
+
        unlock_page(page);
 
-       return 0;
-}
+       offset = 0;
+       while (1) {
+               unsigned sectors = 0, dirty_sectors = 0, reserved_sectors = 0;
+               u64 sector;
 
-int bch2_writepages(struct address_space *mapping, struct writeback_control *wbc)
-{
-       struct bch_fs *c = mapping->host->i_sb->s_fs_info;
-       struct bch_writepage_state w =
-               bch_writepage_state_init(c, to_bch_ei(mapping->host));
-       struct pagecache_iter iter;
-       struct page *page;
-       int ret = 0;
-       int done = 0;
-       pgoff_t uninitialized_var(writeback_index);
-       pgoff_t index;
-       pgoff_t end;            /* Inclusive */
-       pgoff_t done_index;
-       int cycled;
-       int range_whole = 0;
-       int tag;
-
-       if (wbc->range_cyclic) {
-               writeback_index = mapping->writeback_index; /* prev offset */
-               index = writeback_index;
-               if (index == 0)
-                       cycled = 1;
-               else
-                       cycled = 0;
-               end = -1;
-       } else {
-               index = wbc->range_start >> PAGE_SHIFT;
-               end = wbc->range_end >> PAGE_SHIFT;
-               if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
-                       range_whole = 1;
-               cycled = 1; /* ignore range_cyclic tests */
-       }
-       if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
-               tag = PAGECACHE_TAG_TOWRITE;
-       else
-               tag = PAGECACHE_TAG_DIRTY;
-retry:
-       if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
-               tag_pages_for_writeback(mapping, index, end);
-
-       done_index = index;
-get_pages:
-       for_each_pagecache_tag(&iter, mapping, tag, index, end, page) {
-               done_index = page->index;
-
-               if (w.io &&
-                   !bio_can_add_page_contig(&w.io->op.op.wbio.bio, page))
-                       bch2_writepage_do_io(&w);
-
-               if (!w.io &&
-                   atomic_read(&c->writeback_pages) >=
-                   c->writeback_pages_max) {
-                       /* don't sleep with pages pinned: */
-                       pagecache_iter_release(&iter);
-
-                       __wait_event(c->writeback_wait,
-                                    atomic_read(&c->writeback_pages) <
-                                    c->writeback_pages_max);
-                       goto get_pages;
-               }
+               while (offset < PAGE_SECTORS &&
+                      orig.s[offset].state < SECTOR_DIRTY)
+                       offset++;
 
-               lock_page(page);
+               if (offset == PAGE_SECTORS)
+                       break;
 
-               /*
-                * Page truncated or invalidated. We can freely skip it
-                * then, even for data integrity operations: the page
-                * has disappeared concurrently, so there could be no
-                * real expectation of this data interity operation
-                * even if there is now a new, dirty page at the same
-                * pagecache address.
-                */
-               if (unlikely(page->mapping != mapping)) {
-continue_unlock:
-                       unlock_page(page);
-                       continue;
+               while (offset + sectors < PAGE_SECTORS &&
+                      orig.s[offset + sectors].state >= SECTOR_DIRTY) {
+                       reserved_sectors += orig.s[offset + sectors].replicas_reserved;
+                       dirty_sectors += orig.s[offset + sectors].state == SECTOR_DIRTY;
+                       sectors++;
                }
+               BUG_ON(!sectors);
 
-               if (!PageDirty(page)) {
-                       /* someone wrote it for us */
-                       goto continue_unlock;
-               }
+               sector = ((u64) page->index << PAGE_SECTORS_SHIFT) + offset;
 
-               if (PageWriteback(page)) {
-                       if (wbc->sync_mode != WB_SYNC_NONE)
-                               wait_on_page_writeback(page);
-                       else
-                               goto continue_unlock;
-               }
+               if (w->io &&
+                   (w->io->op.res.nr_replicas != nr_replicas_this_write ||
+                    bio_full(&w->io->op.wbio.bio, PAGE_SIZE) ||
+                    w->io->op.wbio.bio.bi_iter.bi_size + (sectors << 9) >=
+                    (BIO_MAX_VECS * PAGE_SIZE) ||
+                    bio_end_sector(&w->io->op.wbio.bio) != sector))
+                       bch2_writepage_do_io(w);
 
-               BUG_ON(PageWriteback(page));
-               if (!clear_page_dirty_for_io(page))
-                       goto continue_unlock;
+               if (!w->io)
+                       bch2_writepage_io_alloc(c, wbc, w, inode, sector,
+                                               nr_replicas_this_write);
 
-               trace_wbc_writepage(wbc, inode_to_bdi(mapping->host));
-               ret = __bch2_writepage(c, page, wbc, &w);
-               if (unlikely(ret)) {
-                       if (ret == AOP_WRITEPAGE_ACTIVATE) {
-                               unlock_page(page);
-                               ret = 0;
-                       } else {
-                               /*
-                                * done_index is set past this page,
-                                * so media errors will not choke
-                                * background writeout for the entire
-                                * file. This has consequences for
-                                * range_cyclic semantics (ie. it may
-                                * not be suitable for data integrity
-                                * writeout).
-                                */
-                               done_index = page->index + 1;
-                               done = 1;
-                               break;
-                       }
-               }
+               atomic_inc(&s->write_count);
 
-               /*
-                * We stop writing back only if we are not doing
-                * integrity sync. In case of integrity sync we have to
-                * keep going until we have written all the pages
-                * we tagged for writeback prior to entering this loop.
-                */
-               if (--wbc->nr_to_write <= 0 &&
-                   wbc->sync_mode == WB_SYNC_NONE) {
-                       done = 1;
-                       break;
-               }
-       }
-       pagecache_iter_release(&iter);
+               BUG_ON(inode != w->io->inode);
+               BUG_ON(!bio_add_page(&w->io->op.wbio.bio, page,
+                                    sectors << 9, offset << 9));
 
-       if (w.io)
-               bch2_writepage_do_io(&w);
+               /* Check for writing past i_size: */
+               WARN_ON((bio_end_sector(&w->io->op.wbio.bio) << 9) >
+                       round_up(i_size, block_bytes(c)));
 
-       if (!cycled && !done) {
-               /*
-                * range_cyclic:
-                * We hit the last page and there is more work to be done: wrap
-                * back to the start of the file
-                */
-               cycled = 1;
-               index = 0;
-               end = writeback_index - 1;
-               goto retry;
+               w->io->op.res.sectors += reserved_sectors;
+               w->io->op.i_sectors_delta -= dirty_sectors;
+               w->io->op.new_i_size = i_size;
+
+               offset += sectors;
        }
-       if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
-               mapping->writeback_index = done_index;
 
+       if (atomic_dec_and_test(&s->write_count))
+               end_page_writeback(page);
+
+       return 0;
+}
+
+int bch2_writepages(struct address_space *mapping, struct writeback_control *wbc)
+{
+       struct bch_fs *c = mapping->host->i_sb->s_fs_info;
+       struct bch_writepage_state w =
+               bch_writepage_state_init(c, to_bch_ei(mapping->host));
+       struct blk_plug plug;
+       int ret;
+
+       blk_start_plug(&plug);
+       ret = write_cache_pages(mapping, wbc, __bch2_writepage, &w);
+       if (w.io)
+               bch2_writepage_do_io(&w);
+       blk_finish_plug(&plug);
        return ret;
 }
 
@@ -1497,7 +1512,7 @@ int bch2_writepage(struct page *page, struct writeback_control *wbc)
                bch_writepage_state_init(c, to_bch_ei(page->mapping->host));
        int ret;
 
-       ret = __bch2_writepage(c, page, wbc, &w);
+       ret = __bch2_writepage(page, wbc, &w);
        if (w.io)
                bch2_writepage_do_io(&w);
 
@@ -1512,15 +1527,20 @@ int bch2_write_begin(struct file *file, struct address_space *mapping,
 {
        struct bch_inode_info *inode = to_bch_ei(mapping->host);
        struct bch_fs *c = inode->v.i_sb->s_fs_info;
+       struct bch2_page_reservation *res;
        pgoff_t index = pos >> PAGE_SHIFT;
        unsigned offset = pos & (PAGE_SIZE - 1);
        struct page *page;
        int ret = -ENOMEM;
 
-       BUG_ON(inode_unhashed(&inode->v));
+       res = kmalloc(sizeof(*res), GFP_KERNEL);
+       if (!res)
+               return -ENOMEM;
+
+       bch2_page_reservation_init(c, inode, res);
+       *fsdata = res;
 
-       /* Not strictly necessary - same reason as mkwrite(): */
-       pagecache_add_get(&mapping->add_lock);
+       bch2_pagecache_add_get(&inode->ei_pagecache_lock);
 
        page = grab_cache_page_write_begin(mapping, index, flags);
        if (!page)
@@ -1549,7 +1569,14 @@ readpage:
        if (ret)
                goto err;
 out:
-       ret = bch2_get_page_reservation(c, inode, page, true);
+       if (!bch2_page_state_create(page, __GFP_NOFAIL)->uptodate) {
+               ret = bch2_page_state_set(c, inode_inum(inode), &page, 1);
+               if (ret)
+                       goto out;
+       }
+
+       ret = bch2_page_reservation_get(c, inode, page, res,
+                                       offset, len, true);
        if (ret) {
                if (!PageUptodate(page)) {
                        /*
@@ -1571,7 +1598,9 @@ err:
        put_page(page);
        *pagep = NULL;
 err_unlock:
-       pagecache_add_put(&mapping->add_lock);
+       bch2_pagecache_add_put(&inode->ei_pagecache_lock);
+       kfree(res);
+       *fsdata = NULL;
        return ret;
 }
 
@@ -1581,6 +1610,8 @@ int bch2_write_end(struct file *file, struct address_space *mapping,
 {
        struct bch_inode_info *inode = to_bch_ei(mapping->host);
        struct bch_fs *c = inode->v.i_sb->s_fs_info;
+       struct bch2_page_reservation *res = fsdata;
+       unsigned offset = pos & (PAGE_SIZE - 1);
 
        lockdep_assert_held(&inode->v.i_rwsem);
 
@@ -1595,89 +1626,321 @@ int bch2_write_end(struct file *file, struct address_space *mapping,
                copied = 0;
        }
 
+       spin_lock(&inode->v.i_lock);
        if (pos + copied > inode->v.i_size)
                i_size_write(&inode->v, pos + copied);
+       spin_unlock(&inode->v.i_lock);
 
        if (copied) {
                if (!PageUptodate(page))
                        SetPageUptodate(page);
-               if (!PageDirty(page))
-                       set_page_dirty(page);
+
+               bch2_set_page_dirty(c, inode, page, res, offset, copied);
 
                inode->ei_last_dirtied = (unsigned long) current;
-       } else {
-               bch2_put_page_reservation(c, inode, page);
        }
 
        unlock_page(page);
        put_page(page);
-       pagecache_add_put(&mapping->add_lock);
+       bch2_pagecache_add_put(&inode->ei_pagecache_lock);
+
+       bch2_page_reservation_put(c, inode, res);
+       kfree(res);
 
        return copied;
 }
 
-/* O_DIRECT reads */
+#define WRITE_BATCH_PAGES      32
 
-static void bch2_dio_read_complete(struct closure *cl)
+static int __bch2_buffered_write(struct bch_inode_info *inode,
+                                struct address_space *mapping,
+                                struct iov_iter *iter,
+                                loff_t pos, unsigned len)
 {
-       struct dio_read *dio = container_of(cl, struct dio_read, cl);
+       struct bch_fs *c = inode->v.i_sb->s_fs_info;
+       struct page *pages[WRITE_BATCH_PAGES];
+       struct bch2_page_reservation res;
+       unsigned long index = pos >> PAGE_SHIFT;
+       unsigned offset = pos & (PAGE_SIZE - 1);
+       unsigned nr_pages = DIV_ROUND_UP(offset + len, PAGE_SIZE);
+       unsigned i, reserved = 0, set_dirty = 0;
+       unsigned copied = 0, nr_pages_copied = 0;
+       int ret = 0;
 
-       dio->req->ki_complete(dio->req, dio->ret, 0);
-       bio_check_pages_dirty(&dio->rbio.bio);  /* transfers ownership */
-}
+       BUG_ON(!len);
+       BUG_ON(nr_pages > ARRAY_SIZE(pages));
 
-static void bch2_direct_IO_read_endio(struct bio *bio)
-{
-       struct dio_read *dio = bio->bi_private;
+       bch2_page_reservation_init(c, inode, &res);
 
-       if (bio->bi_status)
-               dio->ret = blk_status_to_errno(bio->bi_status);
+       for (i = 0; i < nr_pages; i++) {
+               pages[i] = grab_cache_page_write_begin(mapping, index + i, 0);
+               if (!pages[i]) {
+                       nr_pages = i;
+                       if (!i) {
+                               ret = -ENOMEM;
+                               goto out;
+                       }
+                       len = min_t(unsigned, len,
+                                   nr_pages * PAGE_SIZE - offset);
+                       break;
+               }
+       }
 
-       closure_put(&dio->cl);
-}
+       if (offset && !PageUptodate(pages[0])) {
+               ret = bch2_read_single_page(pages[0], mapping);
+               if (ret)
+                       goto out;
+       }
 
-static void bch2_direct_IO_read_split_endio(struct bio *bio)
-{
-       bch2_direct_IO_read_endio(bio);
-       bio_check_pages_dirty(bio);     /* transfers ownership */
-}
+       if ((pos + len) & (PAGE_SIZE - 1) &&
+           !PageUptodate(pages[nr_pages - 1])) {
+               if ((index + nr_pages - 1) << PAGE_SHIFT >= inode->v.i_size) {
+                       zero_user(pages[nr_pages - 1], 0, PAGE_SIZE);
+               } else {
+                       ret = bch2_read_single_page(pages[nr_pages - 1], mapping);
+                       if (ret)
+                               goto out;
+               }
+       }
 
-static int bch2_direct_IO_read(struct kiocb *req, struct iov_iter *iter)
-{
-       struct file *file = req->ki_filp;
-       struct bch_inode_info *inode = file_bch_inode(file);
-       struct bch_fs *c = inode->v.i_sb->s_fs_info;
-       struct bch_io_opts opts = io_opts(c, inode);
-       struct dio_read *dio;
-       struct bio *bio;
-       loff_t offset = req->ki_pos;
-       bool sync = is_sync_kiocb(req);
-       ssize_t ret;
+       while (reserved < len) {
+               unsigned i = (offset + reserved) >> PAGE_SHIFT;
+               struct page *page = pages[i];
+               unsigned pg_offset = (offset + reserved) & (PAGE_SIZE - 1);
+               unsigned pg_len = min_t(unsigned, len - reserved,
+                                       PAGE_SIZE - pg_offset);
+
+               if (!bch2_page_state_create(page, __GFP_NOFAIL)->uptodate) {
+                       ret = bch2_page_state_set(c, inode_inum(inode),
+                                                 pages + i, nr_pages - i);
+                       if (ret)
+                               goto out;
+               }
 
-       if ((offset|iter->count) & (block_bytes(c) - 1))
-               return -EINVAL;
+               ret = bch2_page_reservation_get(c, inode, page, &res,
+                                               pg_offset, pg_len, true);
+               if (ret)
+                       goto out;
 
-       ret = min_t(loff_t, iter->count,
-                   max_t(loff_t, 0, i_size_read(&inode->v) - offset));
-       iov_iter_truncate(iter, round_up(ret, block_bytes(c)));
+               reserved += pg_len;
+       }
 
-       if (!ret)
-               return ret;
+       if (mapping_writably_mapped(mapping))
+               for (i = 0; i < nr_pages; i++)
+                       flush_dcache_page(pages[i]);
 
-       bio = bio_alloc_bioset(GFP_KERNEL,
-                              iov_iter_npages(iter, BIO_MAX_PAGES),
-                              &c->dio_read_bioset);
+       while (copied < len) {
+               struct page *page = pages[(offset + copied) >> PAGE_SHIFT];
+               unsigned pg_offset = (offset + copied) & (PAGE_SIZE - 1);
+               unsigned pg_len = min_t(unsigned, len - copied,
+                                       PAGE_SIZE - pg_offset);
+               unsigned pg_copied = copy_page_from_iter_atomic(page,
+                                               pg_offset, pg_len,iter);
 
-       bio->bi_end_io = bch2_direct_IO_read_endio;
+               if (!pg_copied)
+                       break;
 
-       dio = container_of(bio, struct dio_read, rbio.bio);
-       closure_init(&dio->cl, NULL);
+               if (!PageUptodate(page) &&
+                   pg_copied != PAGE_SIZE &&
+                   pos + copied + pg_copied < inode->v.i_size) {
+                       zero_user(page, 0, PAGE_SIZE);
+                       break;
+               }
 
-       /*
-        * this is a _really_ horrible hack just to avoid an atomic sub at the
-        * end:
-        */
-       if (!sync) {
+               flush_dcache_page(page);
+               copied += pg_copied;
+
+               if (pg_copied != pg_len)
+                       break;
+       }
+
+       if (!copied)
+               goto out;
+
+       spin_lock(&inode->v.i_lock);
+       if (pos + copied > inode->v.i_size)
+               i_size_write(&inode->v, pos + copied);
+       spin_unlock(&inode->v.i_lock);
+
+       while (set_dirty < copied) {
+               struct page *page = pages[(offset + set_dirty) >> PAGE_SHIFT];
+               unsigned pg_offset = (offset + set_dirty) & (PAGE_SIZE - 1);
+               unsigned pg_len = min_t(unsigned, copied - set_dirty,
+                                       PAGE_SIZE - pg_offset);
+
+               if (!PageUptodate(page))
+                       SetPageUptodate(page);
+
+               bch2_set_page_dirty(c, inode, page, &res, pg_offset, pg_len);
+               unlock_page(page);
+               put_page(page);
+
+               set_dirty += pg_len;
+       }
+
+       nr_pages_copied = DIV_ROUND_UP(offset + copied, PAGE_SIZE);
+       inode->ei_last_dirtied = (unsigned long) current;
+out:
+       for (i = nr_pages_copied; i < nr_pages; i++) {
+               unlock_page(pages[i]);
+               put_page(pages[i]);
+       }
+
+       bch2_page_reservation_put(c, inode, &res);
+
+       return copied ?: ret;
+}
+
+static ssize_t bch2_buffered_write(struct kiocb *iocb, struct iov_iter *iter)
+{
+       struct file *file = iocb->ki_filp;
+       struct address_space *mapping = file->f_mapping;
+       struct bch_inode_info *inode = file_bch_inode(file);
+       loff_t pos = iocb->ki_pos;
+       ssize_t written = 0;
+       int ret = 0;
+
+       bch2_pagecache_add_get(&inode->ei_pagecache_lock);
+
+       do {
+               unsigned offset = pos & (PAGE_SIZE - 1);
+               unsigned bytes = min_t(unsigned long, iov_iter_count(iter),
+                             PAGE_SIZE * WRITE_BATCH_PAGES - offset);
+again:
+               /*
+                * Bring in the user page that we will copy from _first_.
+                * Otherwise there's a nasty deadlock on copying from the
+                * same page as we're writing to, without it being marked
+                * up-to-date.
+                *
+                * Not only is this an optimisation, but it is also required
+                * to check that the address is actually valid, when atomic
+                * usercopies are used, below.
+                */
+               if (unlikely(fault_in_iov_iter_readable(iter, bytes))) {
+                       bytes = min_t(unsigned long, iov_iter_count(iter),
+                                     PAGE_SIZE - offset);
+
+                       if (unlikely(fault_in_iov_iter_readable(iter, bytes))) {
+                               ret = -EFAULT;
+                               break;
+                       }
+               }
+
+               if (unlikely(fatal_signal_pending(current))) {
+                       ret = -EINTR;
+                       break;
+               }
+
+               ret = __bch2_buffered_write(inode, mapping, iter, pos, bytes);
+               if (unlikely(ret < 0))
+                       break;
+
+               cond_resched();
+
+               if (unlikely(ret == 0)) {
+                       /*
+                        * If we were unable to copy any data at all, we must
+                        * fall back to a single segment length write.
+                        *
+                        * If we didn't fallback here, we could livelock
+                        * because not all segments in the iov can be copied at
+                        * once without a pagefault.
+                        */
+                       bytes = min_t(unsigned long, PAGE_SIZE - offset,
+                                     iov_iter_single_seg_count(iter));
+                       goto again;
+               }
+               pos += ret;
+               written += ret;
+               ret = 0;
+
+               balance_dirty_pages_ratelimited(mapping);
+       } while (iov_iter_count(iter));
+
+       bch2_pagecache_add_put(&inode->ei_pagecache_lock);
+
+       return written ? written : ret;
+}
+
+/* O_DIRECT reads */
+
+static void bio_check_or_release(struct bio *bio, bool check_dirty)
+{
+       if (check_dirty) {
+               bio_check_pages_dirty(bio);
+       } else {
+               bio_release_pages(bio, false);
+               bio_put(bio);
+       }
+}
+
+static void bch2_dio_read_complete(struct closure *cl)
+{
+       struct dio_read *dio = container_of(cl, struct dio_read, cl);
+
+       dio->req->ki_complete(dio->req, dio->ret);
+       bio_check_or_release(&dio->rbio.bio, dio->should_dirty);
+}
+
+static void bch2_direct_IO_read_endio(struct bio *bio)
+{
+       struct dio_read *dio = bio->bi_private;
+
+       if (bio->bi_status)
+               dio->ret = blk_status_to_errno(bio->bi_status);
+
+       closure_put(&dio->cl);
+}
+
+static void bch2_direct_IO_read_split_endio(struct bio *bio)
+{
+       struct dio_read *dio = bio->bi_private;
+       bool should_dirty = dio->should_dirty;
+
+       bch2_direct_IO_read_endio(bio);
+       bio_check_or_release(bio, should_dirty);
+}
+
+static int bch2_direct_IO_read(struct kiocb *req, struct iov_iter *iter)
+{
+       struct file *file = req->ki_filp;
+       struct bch_inode_info *inode = file_bch_inode(file);
+       struct bch_fs *c = inode->v.i_sb->s_fs_info;
+       struct bch_io_opts opts = io_opts(c, &inode->ei_inode);
+       struct dio_read *dio;
+       struct bio *bio;
+       loff_t offset = req->ki_pos;
+       bool sync = is_sync_kiocb(req);
+       size_t shorten;
+       ssize_t ret;
+
+       if ((offset|iter->count) & (block_bytes(c) - 1))
+               return -EINVAL;
+
+       ret = min_t(loff_t, iter->count,
+                   max_t(loff_t, 0, i_size_read(&inode->v) - offset));
+
+       if (!ret)
+               return ret;
+
+       shorten = iov_iter_count(iter) - round_up(ret, block_bytes(c));
+       iter->count -= shorten;
+
+       bio = bio_alloc_bioset(GFP_KERNEL,
+                              bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS),
+                              &c->dio_read_bioset);
+
+       bio->bi_end_io = bch2_direct_IO_read_endio;
+
+       dio = container_of(bio, struct dio_read, rbio.bio);
+       closure_init(&dio->cl, NULL);
+
+       /*
+        * this is a _really_ horrible hack just to avoid an atomic sub at the
+        * end:
+        */
+       if (!sync) {
                set_closure_fn(&dio->cl, bch2_dio_read_complete, NULL);
                atomic_set(&dio->cl.remaining,
                           CLOSURE_REMAINING_INITIALIZER -
@@ -1690,11 +1953,17 @@ static int bch2_direct_IO_read(struct kiocb *req, struct iov_iter *iter)
 
        dio->req        = req;
        dio->ret        = ret;
+       /*
+        * This is one of the sketchier things I've encountered: we have to skip
+        * the dirtying of requests that are internal from the kernel (i.e. from
+        * loopback), because we'll deadlock on page_lock.
+        */
+       dio->should_dirty = iter_is_iovec(iter);
 
        goto start;
        while (iter->count) {
                bio = bio_alloc_bioset(GFP_KERNEL,
-                                      iov_iter_npages(iter, BIO_MAX_PAGES),
+                                      bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS),
                                       &c->bio_read);
                bio->bi_end_io          = bch2_direct_IO_read_split_endio;
 start:
@@ -1711,73 +1980,207 @@ start:
                }
 
                offset += bio->bi_iter.bi_size;
-               bio_set_pages_dirty(bio);
+
+               if (dio->should_dirty)
+                       bio_set_pages_dirty(bio);
 
                if (iter->count)
                        closure_get(&dio->cl);
 
-               bch2_read(c, rbio_init(bio, opts), inode->v.i_ino);
+               bch2_read(c, rbio_init(bio, opts), inode_inum(inode));
        }
 
+       iter->count += shorten;
+
        if (sync) {
                closure_sync(&dio->cl);
                closure_debug_destroy(&dio->cl);
                ret = dio->ret;
-               bio_check_pages_dirty(&dio->rbio.bio); /* transfers ownership */
+               bio_check_or_release(&dio->rbio.bio, dio->should_dirty);
                return ret;
        } else {
                return -EIOCBQUEUED;
        }
 }
 
+ssize_t bch2_read_iter(struct kiocb *iocb, struct iov_iter *iter)
+{
+       struct file *file = iocb->ki_filp;
+       struct bch_inode_info *inode = file_bch_inode(file);
+       struct address_space *mapping = file->f_mapping;
+       size_t count = iov_iter_count(iter);
+       ssize_t ret;
+
+       if (!count)
+               return 0; /* skip atime */
+
+       if (iocb->ki_flags & IOCB_DIRECT) {
+               struct blk_plug plug;
+
+               ret = filemap_write_and_wait_range(mapping,
+                                       iocb->ki_pos,
+                                       iocb->ki_pos + count - 1);
+               if (ret < 0)
+                       return ret;
+
+               file_accessed(file);
+
+               blk_start_plug(&plug);
+               ret = bch2_direct_IO_read(iocb, iter);
+               blk_finish_plug(&plug);
+
+               if (ret >= 0)
+                       iocb->ki_pos += ret;
+       } else {
+               bch2_pagecache_add_get(&inode->ei_pagecache_lock);
+               ret = generic_file_read_iter(iocb, iter);
+               bch2_pagecache_add_put(&inode->ei_pagecache_lock);
+       }
+
+       return ret;
+}
+
 /* O_DIRECT writes */
 
-static void bch2_dio_write_loop_async(struct closure *);
+static bool bch2_check_range_allocated(struct bch_fs *c, subvol_inum inum,
+                                      u64 offset, u64 size,
+                                      unsigned nr_replicas, bool compressed)
+{
+       struct btree_trans trans;
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       u64 end = offset + size;
+       u32 snapshot;
+       bool ret = true;
+       int err;
+
+       bch2_trans_init(&trans, c, 0, 0);
+retry:
+       bch2_trans_begin(&trans);
+
+       err = bch2_subvolume_get_snapshot(&trans, inum.subvol, &snapshot);
+       if (err)
+               goto err;
+
+       for_each_btree_key_norestart(&trans, iter, BTREE_ID_extents,
+                          SPOS(inum.inum, offset, snapshot),
+                          BTREE_ITER_SLOTS, k, err) {
+               if (bkey_cmp(bkey_start_pos(k.k), POS(inum.inum, end)) >= 0)
+                       break;
+
+               if (k.k->p.snapshot != snapshot ||
+                   nr_replicas > bch2_bkey_replicas(c, k) ||
+                   (!compressed && bch2_bkey_sectors_compressed(k))) {
+                       ret = false;
+                       break;
+               }
+       }
+
+       offset = iter.pos.offset;
+       bch2_trans_iter_exit(&trans, &iter);
+err:
+       if (err == -EINTR)
+               goto retry;
+       bch2_trans_exit(&trans);
+
+       return err ? false : ret;
+}
+
+static void bch2_dio_write_loop_async(struct bch_write_op *);
 
 static long bch2_dio_write_loop(struct dio_write *dio)
 {
+       bool kthread = (current->flags & PF_KTHREAD) != 0;
        struct kiocb *req = dio->req;
        struct address_space *mapping = req->ki_filp->f_mapping;
-       struct bch_inode_info *inode = dio->iop.inode;
-       struct bio *bio = &dio->iop.op.wbio.bio;
+       struct bch_inode_info *inode = file_bch_inode(req->ki_filp);
+       struct bch_fs *c = inode->v.i_sb->s_fs_info;
+       struct bio *bio = &dio->op.wbio.bio;
+       struct bvec_iter_all iter;
        struct bio_vec *bv;
-       bool sync;
+       unsigned unaligned, iter_count;
+       bool sync = dio->sync, dropped_locks;
        long ret;
-       int i;
 
        if (dio->loop)
                goto loop;
 
-       inode_dio_begin(&inode->v);
-       __pagecache_block_get(&mapping->add_lock);
-
-       /* Write and invalidate pagecache range that we're writing to: */
-       ret = write_invalidate_inode_pages_range(mapping, req->ki_pos,
-                               req->ki_pos + iov_iter_count(&dio->iter) - 1);
-       if (unlikely(ret))
-               goto err;
+       down(&c->io_in_flight);
 
        while (1) {
-               BUG_ON(current->pagecache_lock);
-               current->pagecache_lock = &mapping->add_lock;
-               if (current != dio->task)
-                       use_mm(dio->task->mm);
+               iter_count = dio->iter.count;
+
+               if (kthread && dio->mm)
+                       kthread_use_mm(dio->mm);
+               BUG_ON(current->faults_disabled_mapping);
+               current->faults_disabled_mapping = mapping;
 
                ret = bio_iov_iter_get_pages(bio, &dio->iter);
 
-               if (current != dio->task)
-                       unuse_mm(dio->task->mm);
-               current->pagecache_lock = NULL;
+               dropped_locks = fdm_dropped_locks();
+
+               current->faults_disabled_mapping = NULL;
+               if (kthread && dio->mm)
+                       kthread_unuse_mm(dio->mm);
+
+               /*
+                * If the fault handler returned an error but also signalled
+                * that it dropped & retook ei_pagecache_lock, we just need to
+                * re-shoot down the page cache and retry:
+                */
+               if (dropped_locks && ret)
+                       ret = 0;
 
                if (unlikely(ret < 0))
                        goto err;
 
-               dio->iop.op.pos = POS(inode->v.i_ino,
-                               (req->ki_pos >> 9) + dio->iop.op.written);
+               if (unlikely(dropped_locks)) {
+                       ret = write_invalidate_inode_pages_range(mapping,
+                                       req->ki_pos,
+                                       req->ki_pos + iter_count - 1);
+                       if (unlikely(ret))
+                               goto err;
 
-               task_io_account_write(bio->bi_iter.bi_size);
+                       if (!bio->bi_iter.bi_size)
+                               continue;
+               }
+
+               unaligned = bio->bi_iter.bi_size & (block_bytes(c) - 1);
+               bio->bi_iter.bi_size -= unaligned;
+               iov_iter_revert(&dio->iter, unaligned);
 
-               closure_call(&dio->iop.op.cl, bch2_write, NULL, &dio->cl);
+               if (!bio->bi_iter.bi_size) {
+                       /*
+                        * bio_iov_iter_get_pages was only able to get <
+                        * blocksize worth of pages:
+                        */
+                       ret = -EFAULT;
+                       goto err;
+               }
+
+               bch2_write_op_init(&dio->op, c, io_opts(c, &inode->ei_inode));
+               dio->op.end_io          = bch2_dio_write_loop_async;
+               dio->op.target          = dio->op.opts.foreground_target;
+               dio->op.write_point     = writepoint_hashed((unsigned long) current);
+               dio->op.nr_replicas     = dio->op.opts.data_replicas;
+               dio->op.subvol          = inode->ei_subvol;
+               dio->op.pos             = POS(inode->v.i_ino, (u64) req->ki_pos >> 9);
+
+               if ((req->ki_flags & IOCB_DSYNC) &&
+                   !c->opts.journal_flush_disabled)
+                       dio->op.flags |= BCH_WRITE_FLUSH;
+               dio->op.flags |= BCH_WRITE_CHECK_ENOSPC;
+
+               ret = bch2_disk_reservation_get(c, &dio->op.res, bio_sectors(bio),
+                                               dio->op.opts.data_replicas, 0);
+               if (unlikely(ret) &&
+                   !bch2_check_range_allocated(c, inode_inum(inode),
+                               dio->op.pos.offset, bio_sectors(bio),
+                               dio->op.opts.data_replicas,
+                               dio->op.opts.compression != 0))
+                       goto err;
+
+               task_io_account_write(bio->bi_iter.bi_size);
 
                if (!dio->sync && !dio->loop && dio->iter.count) {
                        struct iovec *iov = dio->inline_vecs;
@@ -1786,8 +2189,8 @@ static long bch2_dio_write_loop(struct dio_write *dio)
                                iov = kmalloc(dio->iter.nr_segs * sizeof(*iov),
                                              GFP_KERNEL);
                                if (unlikely(!iov)) {
-                                       dio->iop.op.error = -ENOMEM;
-                                       goto err_wait_io;
+                                       dio->sync = sync = true;
+                                       goto do_io;
                                }
 
                                dio->free_iov = true;
@@ -1796,183 +2199,190 @@ static long bch2_dio_write_loop(struct dio_write *dio)
                        memcpy(iov, dio->iter.iov, dio->iter.nr_segs * sizeof(*iov));
                        dio->iter.iov = iov;
                }
-err_wait_io:
+do_io:
                dio->loop = true;
+               closure_call(&dio->op.cl, bch2_write, NULL, NULL);
 
-               if (!dio->sync) {
-                       continue_at_noreturn(&dio->cl,
-                                       bch2_dio_write_loop_async, NULL);
+               if (sync)
+                       wait_for_completion(&dio->done);
+               else
                        return -EIOCBQUEUED;
+loop:
+               i_sectors_acct(c, inode, &dio->quota_res,
+                              dio->op.i_sectors_delta);
+               req->ki_pos += (u64) dio->op.written << 9;
+               dio->written += dio->op.written;
+
+               spin_lock(&inode->v.i_lock);
+               if (req->ki_pos > inode->v.i_size)
+                       i_size_write(&inode->v, req->ki_pos);
+               spin_unlock(&inode->v.i_lock);
+
+               if (likely(!bio_flagged(bio, BIO_NO_PAGE_REF)))
+                       bio_for_each_segment_all(bv, bio, iter)
+                               put_page(bv->bv_page);
+               bio->bi_vcnt = 0;
+
+               if (dio->op.error) {
+                       set_bit(EI_INODE_ERROR, &inode->ei_flags);
+                       break;
                }
 
-               closure_sync(&dio->cl);
-loop:
-               bio_for_each_segment_all(bv, bio, i)
-                       put_page(bv->bv_page);
-               if (!dio->iter.count || dio->iop.op.error)
+               if (!dio->iter.count)
                        break;
+
                bio_reset(bio);
+               reinit_completion(&dio->done);
        }
 
-       ret = dio->iop.op.error ?: ((long) dio->iop.op.written << 9);
+       ret = dio->op.error ?: ((long) dio->written << 9);
 err:
-       __pagecache_block_put(&mapping->add_lock);
-       bch2_disk_reservation_put(dio->iop.op.c, &dio->iop.op.res);
-       bch2_quota_reservation_put(dio->iop.op.c, inode, &dio->quota_res);
+       up(&c->io_in_flight);
+       bch2_pagecache_block_put(&inode->ei_pagecache_lock);
+       bch2_quota_reservation_put(c, inode, &dio->quota_res);
 
        if (dio->free_iov)
                kfree(dio->iter.iov);
 
-       closure_debug_destroy(&dio->cl);
-
-       sync = dio->sync;
+       if (likely(!bio_flagged(bio, BIO_NO_PAGE_REF)))
+               bio_for_each_segment_all(bv, bio, iter)
+                       put_page(bv->bv_page);
        bio_put(bio);
 
        /* inode->i_dio_count is our ref on inode and thus bch_fs */
        inode_dio_end(&inode->v);
 
        if (!sync) {
-               req->ki_complete(req, ret, 0);
+               req->ki_complete(req, ret);
                ret = -EIOCBQUEUED;
        }
        return ret;
 }
 
-static void bch2_dio_write_loop_async(struct closure *cl)
+static void bch2_dio_write_loop_async(struct bch_write_op *op)
 {
-       struct dio_write *dio = container_of(cl, struct dio_write, cl);
+       struct dio_write *dio = container_of(op, struct dio_write, op);
 
-       bch2_dio_write_loop(dio);
+       if (dio->sync)
+               complete(&dio->done);
+       else
+               bch2_dio_write_loop(dio);
 }
 
-static int bch2_direct_IO_write(struct kiocb *req,
-                               struct iov_iter *iter,
-                               bool swap)
+static noinline
+ssize_t bch2_direct_write(struct kiocb *req, struct iov_iter *iter)
 {
        struct file *file = req->ki_filp;
+       struct address_space *mapping = file->f_mapping;
        struct bch_inode_info *inode = file_bch_inode(file);
        struct bch_fs *c = inode->v.i_sb->s_fs_info;
        struct dio_write *dio;
        struct bio *bio;
-       loff_t offset = req->ki_pos;
+       bool locked = true, extending;
        ssize_t ret;
 
-       lockdep_assert_held(&inode->v.i_rwsem);
+       prefetch(&c->opts);
+       prefetch((void *) &c->opts + 64);
+       prefetch(&inode->ei_inode);
+       prefetch((void *) &inode->ei_inode + 64);
 
-       if (unlikely(!iter->count))
-               return 0;
+       inode_lock(&inode->v);
 
-       if (unlikely((offset|iter->count) & (block_bytes(c) - 1)))
-               return -EINVAL;
+       ret = generic_write_checks(req, iter);
+       if (unlikely(ret <= 0))
+               goto err;
+
+       ret = file_remove_privs(file);
+       if (unlikely(ret))
+               goto err;
+
+       ret = file_update_time(file);
+       if (unlikely(ret))
+               goto err;
+
+       if (unlikely((req->ki_pos|iter->count) & (block_bytes(c) - 1)))
+               goto err;
+
+       inode_dio_begin(&inode->v);
+       bch2_pagecache_block_get(&inode->ei_pagecache_lock);
+
+       extending = req->ki_pos + iter->count > inode->v.i_size;
+       if (!extending) {
+               inode_unlock(&inode->v);
+               locked = false;
+       }
 
        bio = bio_alloc_bioset(GFP_KERNEL,
-                              iov_iter_npages(iter, BIO_MAX_PAGES),
+                              bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS),
                               &c->dio_write_bioset);
-       dio = container_of(bio, struct dio_write, iop.op.wbio.bio);
-       closure_init(&dio->cl, NULL);
+       dio = container_of(bio, struct dio_write, op.wbio.bio);
+       init_completion(&dio->done);
        dio->req                = req;
-       dio->task               = current;
+       dio->mm                 = current->mm;
        dio->loop               = false;
-       dio->sync               = is_sync_kiocb(req) ||
-               offset + iter->count > inode->v.i_size;
+       dio->sync               = is_sync_kiocb(req) || extending;
        dio->free_iov           = false;
        dio->quota_res.sectors  = 0;
+       dio->written            = 0;
        dio->iter               = *iter;
-       bch2_fswrite_op_init(&dio->iop, c, inode, io_opts(c, inode), true);
-       dio->iop.op.write_point = writepoint_hashed((unsigned long) dio->task);
-       dio->iop.op.flags |= BCH_WRITE_NOPUT_RESERVATION;
-
-       if ((req->ki_flags & IOCB_DSYNC) &&
-           !c->opts.journal_flush_disabled)
-               dio->iop.op.flags |= BCH_WRITE_FLUSH;
 
        ret = bch2_quota_reservation_add(c, inode, &dio->quota_res,
                                         iter->count >> 9, true);
        if (unlikely(ret))
-               goto err;
-
-       ret = bch2_disk_reservation_get(c, &dio->iop.op.res, iter->count >> 9,
-                                       c->opts.data_replicas, 0);
-       if (unlikely(ret)) {
-               if (bch2_check_range_allocated(c, POS(inode->v.i_ino,
-                                                     offset >> 9),
-                                              iter->count >> 9))
-                       goto err;
-
-               dio->iop.unalloc = true;
-       }
+               goto err_put_bio;
 
-       dio->iop.op.nr_replicas = dio->iop.op.res.nr_replicas;
+       ret = write_invalidate_inode_pages_range(mapping,
+                                       req->ki_pos,
+                                       req->ki_pos + iter->count - 1);
+       if (unlikely(ret))
+               goto err_put_bio;
 
-       return bch2_dio_write_loop(dio);
+       ret = bch2_dio_write_loop(dio);
 err:
-       bch2_disk_reservation_put(c, &dio->iop.op.res);
+       if (locked)
+               inode_unlock(&inode->v);
+       return ret;
+err_put_bio:
+       bch2_pagecache_block_put(&inode->ei_pagecache_lock);
        bch2_quota_reservation_put(c, inode, &dio->quota_res);
-       closure_debug_destroy(&dio->cl);
        bio_put(bio);
-       return ret;
-}
-
-ssize_t bch2_direct_IO(struct kiocb *req, struct iov_iter *iter)
-{
-       struct blk_plug plug;
-       ssize_t ret;
-
-       blk_start_plug(&plug);
-       ret = iov_iter_rw(iter) == WRITE
-               ? bch2_direct_IO_write(req, iter, false)
-               : bch2_direct_IO_read(req, iter);
-       blk_finish_plug(&plug);
-
-       return ret;
-}
-
-static ssize_t
-bch2_direct_write(struct kiocb *iocb, struct iov_iter *iter)
-{
-       return bch2_direct_IO_write(iocb, iter, true);
+       inode_dio_end(&inode->v);
+       goto err;
 }
 
-static ssize_t __bch2_write_iter(struct kiocb *iocb, struct iov_iter *from)
+ssize_t bch2_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
        struct file *file = iocb->ki_filp;
        struct bch_inode_info *inode = file_bch_inode(file);
-       ssize_t ret;
+       ssize_t ret;
+
+       if (iocb->ki_flags & IOCB_DIRECT)
+               return bch2_direct_write(iocb, from);
 
        /* We can write back this queue in page reclaim */
        current->backing_dev_info = inode_to_bdi(&inode->v);
+       inode_lock(&inode->v);
+
+       ret = generic_write_checks(iocb, from);
+       if (ret <= 0)
+               goto unlock;
+
        ret = file_remove_privs(file);
        if (ret)
-               goto out;
+               goto unlock;
 
        ret = file_update_time(file);
        if (ret)
-               goto out;
-
-       ret = iocb->ki_flags & IOCB_DIRECT
-               ? bch2_direct_write(iocb, from)
-               : generic_perform_write(file, from, iocb->ki_pos);
+               goto unlock;
 
+       ret = bch2_buffered_write(iocb, from);
        if (likely(ret > 0))
                iocb->ki_pos += ret;
-out:
+unlock:
+       inode_unlock(&inode->v);
        current->backing_dev_info = NULL;
-       return ret;
-}
-
-ssize_t bch2_write_iter(struct kiocb *iocb, struct iov_iter *from)
-{
-       struct bch_inode_info *inode = file_bch_inode(iocb->ki_filp);
-       bool direct = iocb->ki_flags & IOCB_DIRECT;
-       ssize_t ret;
 
-       inode_lock(&inode->v);
-       ret = generic_write_checks(iocb, from);
        if (ret > 0)
-               ret = __bch2_write_iter(iocb, from);
-       inode_unlock(&inode->v);
-
-       if (ret > 0 && !direct)
                ret = generic_write_sync(iocb, ret);
 
        return ret;
@@ -1980,32 +2390,87 @@ ssize_t bch2_write_iter(struct kiocb *iocb, struct iov_iter *from)
 
 /* fsync: */
 
-int bch2_fsync(struct file *file, loff_t start, loff_t end, int datasync)
+/*
+ * inode->ei_inode.bi_journal_seq won't be up to date since it's set in an
+ * insert trigger: look up the btree inode instead
+ */
+static int bch2_flush_inode(struct bch_fs *c, subvol_inum inum)
 {
-       struct bch_inode_info *inode = file_bch_inode(file);
-       struct bch_fs *c = inode->v.i_sb->s_fs_info;
+       struct bch_inode_unpacked inode;
        int ret;
 
-       ret = filemap_write_and_wait_range(inode->v.i_mapping, start, end);
+       if (c->opts.journal_flush_disabled)
+               return 0;
+
+       ret = bch2_inode_find_by_inum(c, inum, &inode);
        if (ret)
                return ret;
 
-       if (c->opts.journal_flush_disabled)
-               return 0;
+       return bch2_journal_flush_seq(&c->journal, inode.bi_journal_seq);
+}
+
+int bch2_fsync(struct file *file, loff_t start, loff_t end, int datasync)
+{
+       struct bch_inode_info *inode = file_bch_inode(file);
+       struct bch_fs *c = inode->v.i_sb->s_fs_info;
+       int ret, ret2, ret3;
+
+       ret = file_write_and_wait_range(file, start, end);
+       ret2 = sync_inode_metadata(&inode->v, 1);
+       ret3 = bch2_flush_inode(c, inode_inum(inode));
 
-       return bch2_journal_flush_seq(&c->journal, inode->ei_journal_seq);
+       return ret ?: ret2 ?: ret3;
 }
 
 /* truncate: */
 
+static inline int range_has_data(struct bch_fs *c, u32 subvol,
+                                struct bpos start,
+                                struct bpos end)
+{
+       struct btree_trans trans;
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       int ret = 0;
+
+       bch2_trans_init(&trans, c, 0, 0);
+retry:
+       bch2_trans_begin(&trans);
+
+       ret = bch2_subvolume_get_snapshot(&trans, subvol, &start.snapshot);
+       if (ret)
+               goto err;
+
+       for_each_btree_key_norestart(&trans, iter, BTREE_ID_extents, start, 0, k, ret) {
+               if (bkey_cmp(bkey_start_pos(k.k), end) >= 0)
+                       break;
+
+               if (bkey_extent_is_data(k.k)) {
+                       ret = 1;
+                       break;
+               }
+       }
+       start = iter.pos;
+       bch2_trans_iter_exit(&trans, &iter);
+err:
+       if (ret == -EINTR)
+               goto retry;
+
+       bch2_trans_exit(&trans);
+       return ret;
+}
+
 static int __bch2_truncate_page(struct bch_inode_info *inode,
                                pgoff_t index, loff_t start, loff_t end)
 {
        struct bch_fs *c = inode->v.i_sb->s_fs_info;
        struct address_space *mapping = inode->v.i_mapping;
+       struct bch_page_state *s;
        unsigned start_offset = start & (PAGE_SIZE - 1);
        unsigned end_offset = ((end - 1) & (PAGE_SIZE - 1)) + 1;
+       unsigned i;
        struct page *page;
+       s64 i_sectors_delta = 0;
        int ret = 0;
 
        /* Page boundary? Nothing to do */
@@ -2019,30 +2484,16 @@ static int __bch2_truncate_page(struct bch_inode_info *inode,
 
        page = find_lock_page(mapping, index);
        if (!page) {
-               struct btree_iter iter;
-               struct bkey_s_c k = bkey_s_c_null;
-
                /*
                 * XXX: we're doing two index lookups when we end up reading the
                 * page
                 */
-               for_each_btree_key(&iter, c, BTREE_ID_EXTENTS,
-                                  POS(inode->v.i_ino,
-                                      index << PAGE_SECTOR_SHIFT), 0, k) {
-                       if (bkey_cmp(bkey_start_pos(k.k),
-                                    POS(inode->v.i_ino,
-                                        (index + 1) << PAGE_SECTOR_SHIFT)) >= 0)
-                               break;
+               ret = range_has_data(c, inode->ei_subvol,
+                               POS(inode->v.i_ino, index << PAGE_SECTORS_SHIFT),
+                               POS(inode->v.i_ino, (index + 1) << PAGE_SECTORS_SHIFT));
+               if (ret <= 0)
+                       return ret;
 
-                       if (k.k->type != KEY_TYPE_DISCARD &&
-                           k.k->type != BCH_RESERVATION) {
-                               bch2_btree_iter_unlock(&iter);
-                               goto create;
-                       }
-               }
-               bch2_btree_iter_unlock(&iter);
-               return 0;
-create:
                page = find_or_create_page(mapping, index, GFP_KERNEL);
                if (unlikely(!page)) {
                        ret = -ENOMEM;
@@ -2050,31 +2501,59 @@ create:
                }
        }
 
+       s = bch2_page_state_create(page, 0);
+       if (!s) {
+               ret = -ENOMEM;
+               goto unlock;
+       }
+
        if (!PageUptodate(page)) {
                ret = bch2_read_single_page(page, mapping);
                if (ret)
                        goto unlock;
        }
 
+       if (index != start >> PAGE_SHIFT)
+               start_offset = 0;
+       if (index != end >> PAGE_SHIFT)
+               end_offset = PAGE_SIZE;
+
+       for (i = round_up(start_offset, block_bytes(c)) >> 9;
+            i < round_down(end_offset, block_bytes(c)) >> 9;
+            i++) {
+               s->s[i].nr_replicas     = 0;
+               if (s->s[i].state == SECTOR_DIRTY)
+                       i_sectors_delta--;
+               s->s[i].state           = SECTOR_UNALLOCATED;
+       }
+
+       i_sectors_acct(c, inode, NULL, i_sectors_delta);
+
+       /*
+        * Caller needs to know whether this page will be written out by
+        * writeback - doing an i_size update if necessary - or whether it will
+        * be responsible for the i_size update:
+        */
+       ret = s->s[(min_t(u64, inode->v.i_size - (index << PAGE_SHIFT),
+                         PAGE_SIZE) - 1) >> 9].state >= SECTOR_DIRTY;
+
+       zero_user_segment(page, start_offset, end_offset);
+
        /*
         * Bit of a hack - we don't want truncate to fail due to -ENOSPC.
         *
         * XXX: because we aren't currently tracking whether the page has actual
         * data in it (vs. just 0s, or only partially written) this wrong. ick.
         */
-       ret = bch2_get_page_reservation(c, inode, page, false);
-       BUG_ON(ret);
-
-       if (index == start >> PAGE_SHIFT &&
-           index == end >> PAGE_SHIFT)
-               zero_user_segment(page, start_offset, end_offset);
-       else if (index == start >> PAGE_SHIFT)
-               zero_user_segment(page, start_offset, PAGE_SIZE);
-       else if (index == end >> PAGE_SHIFT)
-               zero_user_segment(page, 0, end_offset);
+       BUG_ON(bch2_get_page_disk_reservation(c, inode, page, false));
 
-       if (!PageDirty(page))
-               set_page_dirty(page);
+       /*
+        * This removes any writeable userspace mappings; we need to force
+        * .page_mkwrite to be called again before any mmapped writes, to
+        * redirty the full page:
+        */
+       page_mkclean(page);
+       __set_page_dirty_nobuffers(page);
 unlock:
        unlock_page(page);
        put_page(page);
@@ -2085,472 +2564,725 @@ out:
 static int bch2_truncate_page(struct bch_inode_info *inode, loff_t from)
 {
        return __bch2_truncate_page(inode, from >> PAGE_SHIFT,
-                                   from, from + PAGE_SIZE);
+                                   from, round_up(from, PAGE_SIZE));
+}
+
+static int bch2_truncate_pages(struct bch_inode_info *inode,
+                              loff_t start, loff_t end)
+{
+       int ret = __bch2_truncate_page(inode, start >> PAGE_SHIFT,
+                                      start, end);
+
+       if (ret >= 0 &&
+           start >> PAGE_SHIFT != end >> PAGE_SHIFT)
+               ret = __bch2_truncate_page(inode,
+                                          end >> PAGE_SHIFT,
+                                          start, end);
+       return ret;
 }
 
-int bch2_truncate(struct bch_inode_info *inode, struct iattr *iattr)
+static int bch2_extend(struct user_namespace *mnt_userns,
+                      struct bch_inode_info *inode,
+                      struct bch_inode_unpacked *inode_u,
+                      struct iattr *iattr)
+{
+       struct address_space *mapping = inode->v.i_mapping;
+       int ret;
+
+       /*
+        * sync appends:
+        *
+        * this has to be done _before_ extending i_size:
+        */
+       ret = filemap_write_and_wait_range(mapping, inode_u->bi_size, S64_MAX);
+       if (ret)
+               return ret;
+
+       truncate_setsize(&inode->v, iattr->ia_size);
+
+       return bch2_setattr_nonsize(mnt_userns, inode, iattr);
+}
+
+static int bch2_truncate_finish_fn(struct bch_inode_info *inode,
+                                  struct bch_inode_unpacked *bi,
+                                  void *p)
+{
+       bi->bi_flags &= ~BCH_INODE_I_SIZE_DIRTY;
+       return 0;
+}
+
+static int bch2_truncate_start_fn(struct bch_inode_info *inode,
+                                 struct bch_inode_unpacked *bi, void *p)
+{
+       u64 *new_i_size = p;
+
+       bi->bi_flags |= BCH_INODE_I_SIZE_DIRTY;
+       bi->bi_size = *new_i_size;
+       return 0;
+}
+
+int bch2_truncate(struct user_namespace *mnt_userns,
+                 struct bch_inode_info *inode, struct iattr *iattr)
 {
        struct bch_fs *c = inode->v.i_sb->s_fs_info;
        struct address_space *mapping = inode->v.i_mapping;
-       bool shrink = iattr->ia_size <= inode->v.i_size;
-       struct i_sectors_hook i_sectors_hook =
-               i_sectors_hook_init(inode, BCH_INODE_I_SIZE_DIRTY);
+       struct bch_inode_unpacked inode_u;
+       u64 new_i_size = iattr->ia_size;
+       s64 i_sectors_delta = 0;
        int ret = 0;
 
+       /*
+        * If the truncate call with change the size of the file, the
+        * cmtimes should be updated. If the size will not change, we
+        * do not need to update the cmtimes.
+        */
+       if (iattr->ia_size != inode->v.i_size) {
+               if (!(iattr->ia_valid & ATTR_MTIME))
+                       ktime_get_coarse_real_ts64(&iattr->ia_mtime);
+               if (!(iattr->ia_valid & ATTR_CTIME))
+                       ktime_get_coarse_real_ts64(&iattr->ia_ctime);
+               iattr->ia_valid |= ATTR_MTIME|ATTR_CTIME;
+       }
+
        inode_dio_wait(&inode->v);
-       pagecache_block_get(&mapping->add_lock);
+       bch2_pagecache_block_get(&inode->ei_pagecache_lock);
 
-       truncate_setsize(&inode->v, iattr->ia_size);
+       ret = bch2_inode_find_by_inum(c, inode_inum(inode), &inode_u);
+       if (ret)
+               goto err;
 
-       /* sync appends.. */
-       /* XXX what protects inode->i_size? */
-       if (iattr->ia_size > inode->ei_inode.bi_size)
+       /*
+        * check this before next assertion; on filesystem error our normal
+        * invariants are a bit broken (truncate has to truncate the page cache
+        * before the inode).
+        */
+       ret = bch2_journal_error(&c->journal);
+       if (ret)
+               goto err;
+
+       WARN_ON(!test_bit(EI_INODE_ERROR, &inode->ei_flags) &&
+               inode->v.i_size < inode_u.bi_size);
+
+       if (iattr->ia_size > inode->v.i_size) {
+               ret = bch2_extend(mnt_userns, inode, &inode_u, iattr);
+               goto err;
+       }
+
+       iattr->ia_valid &= ~ATTR_SIZE;
+
+       ret = bch2_truncate_page(inode, iattr->ia_size);
+       if (unlikely(ret < 0))
+               goto err;
+
+       /*
+        * When extending, we're going to write the new i_size to disk
+        * immediately so we need to flush anything above the current on disk
+        * i_size first:
+        *
+        * Also, when extending we need to flush the page that i_size currently
+        * straddles - if it's mapped to userspace, we need to ensure that
+        * userspace has to redirty it and call .mkwrite -> set_page_dirty
+        * again to allocate the part of the page that was extended.
+        */
+       if (iattr->ia_size > inode_u.bi_size)
+               ret = filemap_write_and_wait_range(mapping,
+                               inode_u.bi_size,
+                               iattr->ia_size - 1);
+       else if (iattr->ia_size & (PAGE_SIZE - 1))
                ret = filemap_write_and_wait_range(mapping,
-                                                  inode->ei_inode.bi_size, S64_MAX);
+                               round_down(iattr->ia_size, PAGE_SIZE),
+                               iattr->ia_size - 1);
        if (ret)
-               goto err_put_pagecache;
+               goto err;
+
+       mutex_lock(&inode->ei_update_lock);
+       ret = bch2_write_inode(c, inode, bch2_truncate_start_fn,
+                              &new_i_size, 0);
+       mutex_unlock(&inode->ei_update_lock);
+
+       if (unlikely(ret))
+               goto err;
+
+       truncate_setsize(&inode->v, iattr->ia_size);
 
-       i_sectors_hook.new_i_size = iattr->ia_size;
+       ret = bch2_fpunch(c, inode_inum(inode),
+                       round_up(iattr->ia_size, block_bytes(c)) >> 9,
+                       U64_MAX, &i_sectors_delta);
+       i_sectors_acct(c, inode, NULL, i_sectors_delta);
+
+       WARN_ON(!inode->v.i_size && inode->v.i_blocks &&
+               !bch2_journal_error(&c->journal));
 
-       ret = i_sectors_dirty_start(c, &i_sectors_hook);
        if (unlikely(ret))
                goto err;
 
-       /*
-        * There might be persistent reservations (from fallocate())
-        * above i_size, which bch2_inode_truncate() will discard - we're
-        * only supposed to discard them if we're doing a real truncate
-        * here (new i_size < current i_size):
-        */
-       if (shrink) {
-               ret = bch2_truncate_page(inode, iattr->ia_size);
-               if (unlikely(ret))
-                       goto err;
-
-               ret = bch2_inode_truncate(c, inode->v.i_ino,
-                                         round_up(iattr->ia_size, PAGE_SIZE) >> 9,
-                                         &i_sectors_hook.hook,
-                                         &inode->ei_journal_seq);
-               if (unlikely(ret))
-                       goto err;
-       }
+       mutex_lock(&inode->ei_update_lock);
+       ret = bch2_write_inode(c, inode, bch2_truncate_finish_fn, NULL, 0);
+       mutex_unlock(&inode->ei_update_lock);
 
-       setattr_copy(&inode->v, iattr);
-       inode->v.i_mtime = inode->v.i_ctime = current_time(&inode->v);
+       ret = bch2_setattr_nonsize(mnt_userns, inode, iattr);
 err:
-       /*
-        * On error - in particular, bch2_truncate_page() error - don't clear
-        * I_SIZE_DIRTY, as we've left data above i_size!:
-        */
-       if (ret)
-               i_sectors_hook.flags &= ~BCH_INODE_I_SIZE_DIRTY;
-
-       ret = i_sectors_dirty_finish(c, &i_sectors_hook) ?: ret;
-err_put_pagecache:
-       pagecache_block_put(&mapping->add_lock);
+       bch2_pagecache_block_put(&inode->ei_pagecache_lock);
        return ret;
 }
 
 /* fallocate: */
 
-static long bch2_fpunch(struct bch_inode_info *inode, loff_t offset, loff_t len)
+static int inode_update_times_fn(struct bch_inode_info *inode,
+                                struct bch_inode_unpacked *bi, void *p)
 {
        struct bch_fs *c = inode->v.i_sb->s_fs_info;
-       struct address_space *mapping = inode->v.i_mapping;
-       u64 ino = inode->v.i_ino;
-       u64 discard_start = round_up(offset, PAGE_SIZE) >> 9;
-       u64 discard_end = round_down(offset + len, PAGE_SIZE) >> 9;
-       int ret = 0;
 
-       inode_lock(&inode->v);
-       inode_dio_wait(&inode->v);
-       pagecache_block_get(&mapping->add_lock);
+       bi->bi_mtime = bi->bi_ctime = bch2_current_time(c);
+       return 0;
+}
 
-       ret = __bch2_truncate_page(inode,
-                                  offset >> PAGE_SHIFT,
-                                  offset, offset + len);
-       if (unlikely(ret))
-               goto err;
+static long bchfs_fpunch(struct bch_inode_info *inode, loff_t offset, loff_t len)
+{
+       struct bch_fs *c = inode->v.i_sb->s_fs_info;
+       u64 end         = offset + len;
+       u64 block_start = round_up(offset, block_bytes(c));
+       u64 block_end   = round_down(end, block_bytes(c));
+       bool truncated_last_page;
+       int ret = 0;
 
-       if (offset >> PAGE_SHIFT !=
-           (offset + len) >> PAGE_SHIFT) {
-               ret = __bch2_truncate_page(inode,
-                                          (offset + len) >> PAGE_SHIFT,
-                                          offset, offset + len);
-               if (unlikely(ret))
-                       goto err;
-       }
+       ret = bch2_truncate_pages(inode, offset, end);
+       if (unlikely(ret < 0))
+               goto err;
 
-       truncate_pagecache_range(&inode->v, offset, offset + len - 1);
+       truncated_last_page = ret;
 
-       if (discard_start < discard_end) {
-               /*
-                * We need to pass in a disk reservation here because we might
-                * be splitting a compressed extent into two. This isn't a
-                * problem with truncate because truncate will never split an
-                * extent, only truncate it...
-                */
-               struct disk_reservation disk_res =
-                       bch2_disk_reservation_init(c, 0);
-               struct i_sectors_hook i_sectors_hook =
-                       i_sectors_hook_init(inode, 0);
-               int ret;
+       truncate_pagecache_range(&inode->v, offset, end - 1);
 
-               ret = i_sectors_dirty_start(c, &i_sectors_hook);
-               if (unlikely(ret))
-                       goto err;
+       if (block_start < block_end ) {
+               s64 i_sectors_delta = 0;
 
-               ret = bch2_btree_delete_range(c,
-                               BTREE_ID_EXTENTS,
-                               POS(ino, discard_start),
-                               POS(ino, discard_end),
-                               ZERO_VERSION,
-                               &disk_res,
-                               &i_sectors_hook.hook,
-                               &inode->ei_journal_seq);
+               ret = bch2_fpunch(c, inode_inum(inode),
+                                 block_start >> 9, block_end >> 9,
+                                 &i_sectors_delta);
+               i_sectors_acct(c, inode, NULL, i_sectors_delta);
+       }
 
-               ret = i_sectors_dirty_finish(c, &i_sectors_hook) ?: ret;
+       mutex_lock(&inode->ei_update_lock);
+       if (end >= inode->v.i_size && !truncated_last_page) {
+               ret = bch2_write_inode_size(c, inode, inode->v.i_size,
+                                           ATTR_MTIME|ATTR_CTIME);
+       } else {
+               ret = bch2_write_inode(c, inode, inode_update_times_fn, NULL,
+                                      ATTR_MTIME|ATTR_CTIME);
        }
+       mutex_unlock(&inode->ei_update_lock);
 err:
-       pagecache_block_put(&mapping->add_lock);
-       inode_unlock(&inode->v);
-
        return ret;
 }
 
-static long bch2_fcollapse(struct bch_inode_info *inode,
-                          loff_t offset, loff_t len)
+static long bchfs_fcollapse_finsert(struct bch_inode_info *inode,
+                                  loff_t offset, loff_t len,
+                                  bool insert)
 {
        struct bch_fs *c = inode->v.i_sb->s_fs_info;
        struct address_space *mapping = inode->v.i_mapping;
-       struct btree_iter src;
-       struct btree_iter dst;
-       BKEY_PADDED(k) copy;
-       struct bkey_s_c k;
-       struct i_sectors_hook i_sectors_hook = i_sectors_hook_init(inode, 0);
-       loff_t new_size;
-       int ret;
+       struct bkey_buf copy;
+       struct btree_trans trans;
+       struct btree_iter src, dst, del;
+       loff_t shift, new_size;
+       u64 src_start;
+       int ret = 0;
 
-       if ((offset | len) & (PAGE_SIZE - 1))
+       if ((offset | len) & (block_bytes(c) - 1))
                return -EINVAL;
 
-       bch2_btree_iter_init(&dst, c, BTREE_ID_EXTENTS,
-                            POS(inode->v.i_ino, offset >> 9),
-                            BTREE_ITER_INTENT);
-       /* position will be set from dst iter's position: */
-       bch2_btree_iter_init(&src, c, BTREE_ID_EXTENTS, POS_MIN, 0);
-       bch2_btree_iter_link(&src, &dst);
+       if (insert) {
+               if (inode->v.i_sb->s_maxbytes - inode->v.i_size < len)
+                       return -EFBIG;
 
-       /*
-        * We need i_mutex to keep the page cache consistent with the extents
-        * btree, and the btree consistent with i_size - we don't need outside
-        * locking for the extents btree itself, because we're using linked
-        * iterators
-        */
-       inode_lock(&inode->v);
-       inode_dio_wait(&inode->v);
-       pagecache_block_get(&mapping->add_lock);
+               if (offset >= inode->v.i_size)
+                       return -EINVAL;
 
-       ret = -EINVAL;
-       if (offset + len >= inode->v.i_size)
-               goto err;
+               src_start       = U64_MAX;
+               shift           = len;
+       } else {
+               if (offset + len >= inode->v.i_size)
+                       return -EINVAL;
 
-       if (inode->v.i_size < len)
-               goto err;
+               src_start       = offset + len;
+               shift           = -len;
+       }
 
-       new_size = inode->v.i_size - len;
+       new_size = inode->v.i_size + shift;
 
        ret = write_invalidate_inode_pages_range(mapping, offset, LLONG_MAX);
        if (ret)
-               goto err;
-
-       ret = i_sectors_dirty_start(c, &i_sectors_hook);
-       if (ret)
-               goto err;
+               return ret;
 
-       while (bkey_cmp(dst.pos,
-                       POS(inode->v.i_ino,
-                           round_up(new_size, PAGE_SIZE) >> 9)) < 0) {
-               struct disk_reservation disk_res;
+       if (insert) {
+               i_size_write(&inode->v, new_size);
+               mutex_lock(&inode->ei_update_lock);
+               ret = bch2_write_inode_size(c, inode, new_size,
+                                           ATTR_MTIME|ATTR_CTIME);
+               mutex_unlock(&inode->ei_update_lock);
+       } else {
+               s64 i_sectors_delta = 0;
 
-               bch2_btree_iter_set_pos(&src,
-                       POS(dst.pos.inode, dst.pos.offset + (len >> 9)));
+               ret = bch2_fpunch(c, inode_inum(inode),
+                                 offset >> 9, (offset + len) >> 9,
+                                 &i_sectors_delta);
+               i_sectors_acct(c, inode, NULL, i_sectors_delta);
 
-               ret = bch2_btree_iter_traverse(&dst);
                if (ret)
-                       goto btree_iter_err;
-
-               k = bch2_btree_iter_peek_with_holes(&src);
-               if ((ret = btree_iter_err(k)))
-                       goto btree_iter_err;
+                       return ret;
+       }
 
-               bkey_reassemble(&copy.k, k);
+       bch2_bkey_buf_init(&copy);
+       bch2_trans_init(&trans, c, BTREE_ITER_MAX, 1024);
+       bch2_trans_iter_init(&trans, &src, BTREE_ID_extents,
+                       POS(inode->v.i_ino, src_start >> 9),
+                       BTREE_ITER_INTENT);
+       bch2_trans_copy_iter(&dst, &src);
+       bch2_trans_copy_iter(&del, &src);
 
-               if (bkey_deleted(&copy.k.k))
-                       copy.k.k.type = KEY_TYPE_DISCARD;
+       while (ret == 0 || ret == -EINTR) {
+               struct disk_reservation disk_res =
+                       bch2_disk_reservation_init(c, 0);
+               struct bkey_i delete;
+               struct bkey_s_c k;
+               struct bpos next_pos;
+               struct bpos move_pos = POS(inode->v.i_ino, offset >> 9);
+               struct bpos atomic_end;
+               unsigned trigger_flags = 0;
+               u32 snapshot;
 
-               bch2_cut_front(src.pos, &copy.k);
-               copy.k.k.p.offset -= len >> 9;
+               bch2_trans_begin(&trans);
 
-               BUG_ON(bkey_cmp(dst.pos, bkey_start_pos(&copy.k.k)));
+               ret = bch2_subvolume_get_snapshot(&trans,
+                                       inode->ei_subvol, &snapshot);
+               if (ret)
+                       continue;
 
-               ret = bch2_disk_reservation_get(c, &disk_res, copy.k.k.size,
-                               bch2_extent_nr_dirty_ptrs(bkey_i_to_s_c(&copy.k)),
-                               BCH_DISK_RESERVATION_NOFAIL);
-               BUG_ON(ret);
+               bch2_btree_iter_set_snapshot(&src, snapshot);
+               bch2_btree_iter_set_snapshot(&dst, snapshot);
+               bch2_btree_iter_set_snapshot(&del, snapshot);
 
-               ret = bch2_btree_insert_at(c, &disk_res, &i_sectors_hook.hook,
-                                          &inode->ei_journal_seq,
-                                          BTREE_INSERT_ATOMIC|
-                                          BTREE_INSERT_NOFAIL,
-                                          BTREE_INSERT_ENTRY(&dst, &copy.k));
-               bch2_disk_reservation_put(c, &disk_res);
-btree_iter_err:
-               if (ret == -EINTR)
-                       ret = 0;
-               if (ret)
-                       goto err_put_sectors_dirty;
-               /*
-                * XXX: if we error here we've left data with multiple
-                * pointers... which isn't a _super_ serious problem...
-                */
+               bch2_trans_begin(&trans);
 
-               bch2_btree_iter_cond_resched(&src);
-       }
+               k = insert
+                       ? bch2_btree_iter_peek_prev(&src)
+                       : bch2_btree_iter_peek(&src);
+               if ((ret = bkey_err(k)))
+                       continue;
 
-       bch2_btree_iter_unlock(&src);
-       bch2_btree_iter_unlock(&dst);
+               if (!k.k || k.k->p.inode != inode->v.i_ino)
+                       break;
 
-       ret = bch2_inode_truncate(c, inode->v.i_ino,
-                                round_up(new_size, PAGE_SIZE) >> 9,
-                                &i_sectors_hook.hook,
-                                &inode->ei_journal_seq);
-       if (ret)
-               goto err_put_sectors_dirty;
+               if (insert &&
+                   bkey_cmp(k.k->p, POS(inode->v.i_ino, offset >> 9)) <= 0)
+                       break;
+reassemble:
+               bch2_bkey_buf_reassemble(&copy, c, k);
 
-       i_size_write(&inode->v, new_size);
-       i_sectors_hook.new_i_size = new_size;
-err_put_sectors_dirty:
-       ret = i_sectors_dirty_finish(c, &i_sectors_hook) ?: ret;
-err:
-       pagecache_block_put(&mapping->add_lock);
-       inode_unlock(&inode->v);
+               if (insert &&
+                   bkey_cmp(bkey_start_pos(k.k), move_pos) < 0)
+                       bch2_cut_front(move_pos, copy.k);
 
-       bch2_btree_iter_unlock(&src);
-       bch2_btree_iter_unlock(&dst);
-       return ret;
-}
+               copy.k->k.p.offset += shift >> 9;
+               bch2_btree_iter_set_pos(&dst, bkey_start_pos(&copy.k->k));
 
-static long bch2_fallocate(struct bch_inode_info *inode, int mode,
-                          loff_t offset, loff_t len)
-{
-       struct address_space *mapping = inode->v.i_mapping;
-       struct bch_fs *c = inode->v.i_sb->s_fs_info;
-       struct i_sectors_hook i_sectors_hook = i_sectors_hook_init(inode, 0);
-       struct btree_iter iter;
-       struct bpos end_pos;
-       loff_t block_start, block_end;
-       loff_t end = offset + len;
-       unsigned sectors;
-       unsigned replicas = READ_ONCE(c->opts.data_replicas);
-       int ret;
+               ret = bch2_extent_atomic_end(&trans, &dst, copy.k, &atomic_end);
+               if (ret)
+                       continue;
 
-       bch2_btree_iter_init(&iter, c, BTREE_ID_EXTENTS, POS_MIN,
-                            BTREE_ITER_INTENT);
+               if (bkey_cmp(atomic_end, copy.k->k.p)) {
+                       if (insert) {
+                               move_pos = atomic_end;
+                               move_pos.offset -= shift >> 9;
+                               goto reassemble;
+                       } else {
+                               bch2_cut_back(atomic_end, copy.k);
+                       }
+               }
 
-       inode_lock(&inode->v);
-       inode_dio_wait(&inode->v);
-       pagecache_block_get(&mapping->add_lock);
+               bkey_init(&delete.k);
+               delete.k.p = copy.k->k.p;
+               delete.k.size = copy.k->k.size;
+               delete.k.p.offset -= shift >> 9;
+               bch2_btree_iter_set_pos(&del, bkey_start_pos(&delete.k));
 
-       if (!(mode & FALLOC_FL_KEEP_SIZE) && end > inode->v.i_size) {
-               ret = inode_newsize_ok(&inode->v, end);
-               if (ret)
-                       goto err;
-       }
+               next_pos = insert ? bkey_start_pos(&delete.k) : delete.k.p;
 
-       if (mode & FALLOC_FL_ZERO_RANGE) {
-               ret = __bch2_truncate_page(inode,
-                                          offset >> PAGE_SHIFT,
-                                          offset, end);
+               if (copy.k->k.size == k.k->size) {
+                       /*
+                        * If we're moving the entire extent, we can skip
+                        * running triggers:
+                        */
+                       trigger_flags |= BTREE_TRIGGER_NORUN;
+               } else {
+                       /* We might end up splitting compressed extents: */
+                       unsigned nr_ptrs =
+                               bch2_bkey_nr_ptrs_allocated(bkey_i_to_s_c(copy.k));
+
+                       ret = bch2_disk_reservation_get(c, &disk_res,
+                                       copy.k->k.size, nr_ptrs,
+                                       BCH_DISK_RESERVATION_NOFAIL);
+                       BUG_ON(ret);
+               }
 
-               if (!ret &&
-                   offset >> PAGE_SHIFT != end >> PAGE_SHIFT)
-                       ret = __bch2_truncate_page(inode,
-                                                  end >> PAGE_SHIFT,
-                                                  offset, end);
+               ret =   bch2_btree_iter_traverse(&del) ?:
+                       bch2_trans_update(&trans, &del, &delete, trigger_flags) ?:
+                       bch2_trans_update(&trans, &dst, copy.k, trigger_flags) ?:
+                       bch2_trans_commit(&trans, &disk_res, NULL,
+                                         BTREE_INSERT_NOFAIL);
+               bch2_disk_reservation_put(c, &disk_res);
 
-               if (unlikely(ret))
-                       goto err;
+               if (!ret)
+                       bch2_btree_iter_set_pos(&src, next_pos);
+       }
+       bch2_trans_iter_exit(&trans, &del);
+       bch2_trans_iter_exit(&trans, &dst);
+       bch2_trans_iter_exit(&trans, &src);
+       bch2_trans_exit(&trans);
+       bch2_bkey_buf_exit(&copy, c);
 
-               truncate_pagecache_range(&inode->v, offset, end - 1);
+       if (ret)
+               return ret;
 
-               block_start     = round_up(offset, PAGE_SIZE);
-               block_end       = round_down(end, PAGE_SIZE);
+       mutex_lock(&inode->ei_update_lock);
+       if (!insert) {
+               i_size_write(&inode->v, new_size);
+               ret = bch2_write_inode_size(c, inode, new_size,
+                                           ATTR_MTIME|ATTR_CTIME);
        } else {
-               block_start     = round_down(offset, PAGE_SIZE);
-               block_end       = round_up(end, PAGE_SIZE);
+               /* We need an inode update to update bi_journal_seq for fsync: */
+               ret = bch2_write_inode(c, inode, inode_update_times_fn, NULL,
+                                      ATTR_MTIME|ATTR_CTIME);
        }
+       mutex_unlock(&inode->ei_update_lock);
+       return ret;
+}
+
+static int __bchfs_fallocate(struct bch_inode_info *inode, int mode,
+                            u64 start_sector, u64 end_sector)
+{
+       struct bch_fs *c = inode->v.i_sb->s_fs_info;
+       struct btree_trans trans;
+       struct btree_iter iter;
+       struct bpos end_pos = POS(inode->v.i_ino, end_sector);
+       unsigned replicas = io_opts(c, &inode->ei_inode).data_replicas;
+       int ret = 0;
 
-       bch2_btree_iter_set_pos(&iter, POS(inode->v.i_ino, block_start >> 9));
-       end_pos = POS(inode->v.i_ino, block_end >> 9);
+       bch2_trans_init(&trans, c, BTREE_ITER_MAX, 512);
 
-       ret = i_sectors_dirty_start(c, &i_sectors_hook);
-       if (unlikely(ret))
-               goto err;
+       bch2_trans_iter_init(&trans, &iter, BTREE_ID_extents,
+                       POS(inode->v.i_ino, start_sector),
+                       BTREE_ITER_SLOTS|BTREE_ITER_INTENT);
 
-       while (bkey_cmp(iter.pos, end_pos) < 0) {
+       while (!ret && bkey_cmp(iter.pos, end_pos) < 0) {
+               s64 i_sectors_delta = 0;
                struct disk_reservation disk_res = { 0 };
+               struct quota_res quota_res = { 0 };
                struct bkey_i_reservation reservation;
                struct bkey_s_c k;
+               unsigned sectors;
+               u32 snapshot;
+
+               bch2_trans_begin(&trans);
+
+               ret = bch2_subvolume_get_snapshot(&trans,
+                                       inode->ei_subvol, &snapshot);
+               if (ret)
+                       goto bkey_err;
+
+               bch2_btree_iter_set_snapshot(&iter, snapshot);
 
-               k = bch2_btree_iter_peek_with_holes(&iter);
-               if ((ret = btree_iter_err(k)))
-                       goto btree_iter_err;
+               k = bch2_btree_iter_peek_slot(&iter);
+               if ((ret = bkey_err(k)))
+                       goto bkey_err;
 
                /* already reserved */
-               if (k.k->type == BCH_RESERVATION &&
+               if (k.k->type == KEY_TYPE_reservation &&
                    bkey_s_c_to_reservation(k).v->nr_replicas >= replicas) {
-                       bch2_btree_iter_advance_pos(&iter);
+                       bch2_btree_iter_advance(&iter);
                        continue;
                }
 
-               if (bkey_extent_is_data(k.k)) {
-                       if (!(mode & FALLOC_FL_ZERO_RANGE)) {
-                               bch2_btree_iter_advance_pos(&iter);
-                               continue;
-                       }
+               if (bkey_extent_is_data(k.k) &&
+                   !(mode & FALLOC_FL_ZERO_RANGE)) {
+                       bch2_btree_iter_advance(&iter);
+                       continue;
                }
 
                bkey_reservation_init(&reservation.k_i);
-               reservation.k.type      = BCH_RESERVATION;
+               reservation.k.type      = KEY_TYPE_reservation;
                reservation.k.p         = k.k->p;
                reservation.k.size      = k.k->size;
 
-               bch2_cut_front(iter.pos, &reservation.k_i);
-               bch2_cut_back(end_pos, &reservation.k);
+               bch2_cut_front(iter.pos,        &reservation.k_i);
+               bch2_cut_back(end_pos,          &reservation.k_i);
 
                sectors = reservation.k.size;
-               reservation.v.nr_replicas = bch2_extent_nr_dirty_ptrs(k);
+               reservation.v.nr_replicas = bch2_bkey_nr_ptrs_allocated(k);
 
                if (!bkey_extent_is_allocation(k.k)) {
                        ret = bch2_quota_reservation_add(c, inode,
-                                       &i_sectors_hook.quota_res,
+                                       &quota_res,
                                        sectors, true);
                        if (unlikely(ret))
-                               goto err_put_sectors_dirty;
+                               goto bkey_err;
                }
 
                if (reservation.v.nr_replicas < replicas ||
-                   bch2_extent_is_compressed(k)) {
+                   bch2_bkey_sectors_compressed(k)) {
                        ret = bch2_disk_reservation_get(c, &disk_res, sectors,
                                                        replicas, 0);
                        if (unlikely(ret))
-                               goto err_put_sectors_dirty;
+                               goto bkey_err;
 
                        reservation.v.nr_replicas = disk_res.nr_replicas;
                }
 
-               ret = bch2_btree_insert_at(c, &disk_res, &i_sectors_hook.hook,
-                                         &inode->ei_journal_seq,
-                                         BTREE_INSERT_ATOMIC|
-                                         BTREE_INSERT_NOFAIL,
-                                         BTREE_INSERT_ENTRY(&iter, &reservation.k_i));
+               ret = bch2_extent_update(&trans, inode_inum(inode), &iter,
+                                        &reservation.k_i,
+                               &disk_res, NULL,
+                               0, &i_sectors_delta, true);
+               if (ret)
+                       goto bkey_err;
+               i_sectors_acct(c, inode, &quota_res, i_sectors_delta);
+bkey_err:
+               bch2_quota_reservation_put(c, inode, &quota_res);
                bch2_disk_reservation_put(c, &disk_res);
-btree_iter_err:
-               if (ret < 0 && ret != -EINTR)
-                       goto err_put_sectors_dirty;
-
+               if (ret == -EINTR)
+                       ret = 0;
        }
-       bch2_btree_iter_unlock(&iter);
 
-       ret = i_sectors_dirty_finish(c, &i_sectors_hook) ?: ret;
+       bch2_trans_unlock(&trans); /* lock ordering, before taking pagecache locks: */
+       mark_pagecache_reserved(inode, start_sector, iter.pos.offset);
 
-       if (!(mode & FALLOC_FL_KEEP_SIZE) &&
-           end > inode->v.i_size) {
-               i_size_write(&inode->v, end);
+       if (ret == -ENOSPC && (mode & FALLOC_FL_ZERO_RANGE)) {
+               struct quota_res quota_res = { 0 };
+               s64 i_sectors_delta = 0;
 
-               mutex_lock(&inode->ei_update_lock);
-               ret = bch2_write_inode_size(c, inode, inode->v.i_size);
-               mutex_unlock(&inode->ei_update_lock);
+               bch2_fpunch_at(&trans, &iter, inode_inum(inode),
+                              end_sector, &i_sectors_delta);
+               i_sectors_acct(c, inode, &quota_res, i_sectors_delta);
+               bch2_quota_reservation_put(c, inode, &quota_res);
        }
 
-       /* blech */
-       if ((mode & FALLOC_FL_KEEP_SIZE) &&
-           (mode & FALLOC_FL_ZERO_RANGE) &&
-           inode->ei_inode.bi_size != inode->v.i_size) {
-               /* sync appends.. */
-               ret = filemap_write_and_wait_range(mapping,
-                                       inode->ei_inode.bi_size, S64_MAX);
+       bch2_trans_iter_exit(&trans, &iter);
+       bch2_trans_exit(&trans);
+       return ret;
+}
+
+static long bchfs_fallocate(struct bch_inode_info *inode, int mode,
+                           loff_t offset, loff_t len)
+{
+       struct bch_fs *c = inode->v.i_sb->s_fs_info;
+       u64 end         = offset + len;
+       u64 block_start = round_down(offset,    block_bytes(c));
+       u64 block_end   = round_up(end,         block_bytes(c));
+       bool truncated_last_page = false;
+       int ret, ret2 = 0;
+
+       if (!(mode & FALLOC_FL_KEEP_SIZE) && end > inode->v.i_size) {
+               ret = inode_newsize_ok(&inode->v, end);
                if (ret)
-                       goto err;
+                       return ret;
+       }
 
-               if (inode->ei_inode.bi_size != inode->v.i_size) {
-                       mutex_lock(&inode->ei_update_lock);
-                       ret = bch2_write_inode_size(c, inode, inode->v.i_size);
-                       mutex_unlock(&inode->ei_update_lock);
-               }
+       if (mode & FALLOC_FL_ZERO_RANGE) {
+               ret = bch2_truncate_pages(inode, offset, end);
+               if (unlikely(ret < 0))
+                       return ret;
+
+               truncated_last_page = ret;
+
+               truncate_pagecache_range(&inode->v, offset, end - 1);
+
+               block_start     = round_up(offset,      block_bytes(c));
+               block_end       = round_down(end,       block_bytes(c));
        }
 
-       pagecache_block_put(&mapping->add_lock);
-       inode_unlock(&inode->v);
+       ret = __bchfs_fallocate(inode, mode, block_start >> 9, block_end >> 9);
 
-       return 0;
-err_put_sectors_dirty:
-       ret = i_sectors_dirty_finish(c, &i_sectors_hook) ?: ret;
-err:
-       bch2_btree_iter_unlock(&iter);
-       pagecache_block_put(&mapping->add_lock);
-       inode_unlock(&inode->v);
-       return ret;
+       /*
+        * On -ENOSPC in ZERO_RANGE mode, we still want to do the inode update,
+        * so that the VFS cache i_size is consistent with the btree i_size:
+        */
+       if (ret &&
+           !(ret == -ENOSPC && (mode & FALLOC_FL_ZERO_RANGE)))
+               return ret;
+
+       if (mode & FALLOC_FL_KEEP_SIZE && end > inode->v.i_size)
+               end = inode->v.i_size;
+
+       if (end >= inode->v.i_size &&
+           (((mode & FALLOC_FL_ZERO_RANGE) && !truncated_last_page) ||
+            !(mode & FALLOC_FL_KEEP_SIZE))) {
+               spin_lock(&inode->v.i_lock);
+               i_size_write(&inode->v, end);
+               spin_unlock(&inode->v.i_lock);
+
+               mutex_lock(&inode->ei_update_lock);
+               ret2 = bch2_write_inode_size(c, inode, end, 0);
+               mutex_unlock(&inode->ei_update_lock);
+       }
+
+       return ret ?: ret2;
 }
 
 long bch2_fallocate_dispatch(struct file *file, int mode,
                             loff_t offset, loff_t len)
 {
        struct bch_inode_info *inode = file_bch_inode(file);
+       struct bch_fs *c = inode->v.i_sb->s_fs_info;
+       long ret;
+
+       if (!percpu_ref_tryget(&c->writes))
+               return -EROFS;
+
+       inode_lock(&inode->v);
+       inode_dio_wait(&inode->v);
+       bch2_pagecache_block_get(&inode->ei_pagecache_lock);
 
        if (!(mode & ~(FALLOC_FL_KEEP_SIZE|FALLOC_FL_ZERO_RANGE)))
-               return bch2_fallocate(inode, mode, offset, len);
+               ret = bchfs_fallocate(inode, mode, offset, len);
+       else if (mode == (FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE))
+               ret = bchfs_fpunch(inode, offset, len);
+       else if (mode == FALLOC_FL_INSERT_RANGE)
+               ret = bchfs_fcollapse_finsert(inode, offset, len, true);
+       else if (mode == FALLOC_FL_COLLAPSE_RANGE)
+               ret = bchfs_fcollapse_finsert(inode, offset, len, false);
+       else
+               ret = -EOPNOTSUPP;
+
+
+       bch2_pagecache_block_put(&inode->ei_pagecache_lock);
+       inode_unlock(&inode->v);
+       percpu_ref_put(&c->writes);
+
+       return ret;
+}
+
+loff_t bch2_remap_file_range(struct file *file_src, loff_t pos_src,
+                            struct file *file_dst, loff_t pos_dst,
+                            loff_t len, unsigned remap_flags)
+{
+       struct bch_inode_info *src = file_bch_inode(file_src);
+       struct bch_inode_info *dst = file_bch_inode(file_dst);
+       struct bch_fs *c = src->v.i_sb->s_fs_info;
+       s64 i_sectors_delta = 0;
+       u64 aligned_len;
+       loff_t ret = 0;
+
+       if (remap_flags & ~(REMAP_FILE_DEDUP|REMAP_FILE_ADVISORY))
+               return -EINVAL;
 
-       if (mode == (FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE))
-               return bch2_fpunch(inode, offset, len);
+       if (remap_flags & REMAP_FILE_DEDUP)
+               return -EOPNOTSUPP;
 
-       if (mode == FALLOC_FL_COLLAPSE_RANGE)
-               return bch2_fcollapse(inode, offset, len);
+       if ((pos_src & (block_bytes(c) - 1)) ||
+           (pos_dst & (block_bytes(c) - 1)))
+               return -EINVAL;
+
+       if (src == dst &&
+           abs(pos_src - pos_dst) < len)
+               return -EINVAL;
+
+       bch2_lock_inodes(INODE_LOCK|INODE_PAGECACHE_BLOCK, src, dst);
+
+       file_update_time(file_dst);
+
+       inode_dio_wait(&src->v);
+       inode_dio_wait(&dst->v);
+
+       ret = generic_remap_file_range_prep(file_src, pos_src,
+                                           file_dst, pos_dst,
+                                           &len, remap_flags);
+       if (ret < 0 || len == 0)
+               goto err;
+
+       aligned_len = round_up((u64) len, block_bytes(c));
+
+       ret = write_invalidate_inode_pages_range(dst->v.i_mapping,
+                               pos_dst, pos_dst + len - 1);
+       if (ret)
+               goto err;
+
+       mark_pagecache_unallocated(src, pos_src >> 9,
+                                  (pos_src + aligned_len) >> 9);
+
+       ret = bch2_remap_range(c,
+                              inode_inum(dst), pos_dst >> 9,
+                              inode_inum(src), pos_src >> 9,
+                              aligned_len >> 9,
+                              pos_dst + len, &i_sectors_delta);
+       if (ret < 0)
+               goto err;
 
-       return -EOPNOTSUPP;
+       /*
+        * due to alignment, we might have remapped slightly more than requsted
+        */
+       ret = min((u64) ret << 9, (u64) len);
+
+       /* XXX get a quota reservation */
+       i_sectors_acct(c, dst, NULL, i_sectors_delta);
+
+       spin_lock(&dst->v.i_lock);
+       if (pos_dst + ret > dst->v.i_size)
+               i_size_write(&dst->v, pos_dst + ret);
+       spin_unlock(&dst->v.i_lock);
+
+       if ((file_dst->f_flags & (__O_SYNC | O_DSYNC)) ||
+           IS_SYNC(file_inode(file_dst)))
+               ret = bch2_flush_inode(c, inode_inum(dst));
+err:
+       bch2_unlock_inodes(INODE_LOCK|INODE_PAGECACHE_BLOCK, src, dst);
+
+       return ret;
 }
 
 /* fseek: */
 
-static bool page_is_data(struct page *page)
+static int page_data_offset(struct page *page, unsigned offset)
 {
-       /* XXX: should only have to check PageDirty */
-       return PagePrivate(page) &&
-               (page_state(page)->sectors ||
-                page_state(page)->dirty_sectors);
+       struct bch_page_state *s = bch2_page_state(page);
+       unsigned i;
+
+       if (s)
+               for (i = offset >> 9; i < PAGE_SECTORS; i++)
+                       if (s->s[i].state >= SECTOR_DIRTY)
+                               return i << 9;
+
+       return -1;
 }
 
-static loff_t bch2_next_pagecache_data(struct inode *vinode,
+static loff_t bch2_seek_pagecache_data(struct inode *vinode,
                                       loff_t start_offset,
                                       loff_t end_offset)
 {
        struct address_space *mapping = vinode->i_mapping;
        struct page *page;
-       pgoff_t index;
-
-       for (index = start_offset >> PAGE_SHIFT;
-            index < end_offset >> PAGE_SHIFT;
-            index++) {
-               if (find_get_pages(mapping, index, 1, &page)) {
+       pgoff_t start_index     = start_offset >> PAGE_SHIFT;
+       pgoff_t end_index       = end_offset >> PAGE_SHIFT;
+       pgoff_t index           = start_index;
+       loff_t ret;
+       int offset;
+
+       while (index <= end_index) {
+               if (find_get_pages_range(mapping, &index, end_index, 1, &page)) {
                        lock_page(page);
-                       index = page->index;
 
-                       if (page_is_data(page))
-                               end_offset =
-                                       min(end_offset,
-                                       max(start_offset,
-                                           ((loff_t) index) << PAGE_SHIFT));
+                       offset = page_data_offset(page,
+                                       page->index == start_index
+                                       ? start_offset & (PAGE_SIZE - 1)
+                                       : 0);
+                       if (offset >= 0) {
+                               ret = clamp(((loff_t) page->index << PAGE_SHIFT) +
+                                           offset,
+                                           start_offset, end_offset);
+                               unlock_page(page);
+                               put_page(page);
+                               return ret;
+                       }
+
                        unlock_page(page);
                        put_page(page);
                } else {
@@ -2565,17 +3297,28 @@ static loff_t bch2_seek_data(struct file *file, u64 offset)
 {
        struct bch_inode_info *inode = file_bch_inode(file);
        struct bch_fs *c = inode->v.i_sb->s_fs_info;
+       struct btree_trans trans;
        struct btree_iter iter;
        struct bkey_s_c k;
+       subvol_inum inum = inode_inum(inode);
        u64 isize, next_data = MAX_LFS_FILESIZE;
+       u32 snapshot;
        int ret;
 
        isize = i_size_read(&inode->v);
        if (offset >= isize)
                return -ENXIO;
 
-       for_each_btree_key(&iter, c, BTREE_ID_EXTENTS,
-                          POS(inode->v.i_ino, offset >> 9), 0, k) {
+       bch2_trans_init(&trans, c, 0, 0);
+retry:
+       bch2_trans_begin(&trans);
+
+       ret = bch2_subvolume_get_snapshot(&trans, inum.subvol, &snapshot);
+       if (ret)
+               goto err;
+
+       for_each_btree_key_norestart(&trans, iter, BTREE_ID_extents,
+                          SPOS(inode->v.i_ino, offset >> 9, snapshot), 0, k, ret) {
                if (k.k->p.inode != inode->v.i_ino) {
                        break;
                } else if (bkey_extent_is_data(k.k)) {
@@ -2584,49 +3327,75 @@ static loff_t bch2_seek_data(struct file *file, u64 offset)
                } else if (k.k->p.offset >> 9 > isize)
                        break;
        }
+       bch2_trans_iter_exit(&trans, &iter);
+err:
+       if (ret == -EINTR)
+               goto retry;
 
-       ret = bch2_btree_iter_unlock(&iter);
+       bch2_trans_exit(&trans);
        if (ret)
                return ret;
 
        if (next_data > offset)
-               next_data = bch2_next_pagecache_data(&inode->v,
+               next_data = bch2_seek_pagecache_data(&inode->v,
                                                     offset, next_data);
 
-       if (next_data > isize)
+       if (next_data >= isize)
                return -ENXIO;
 
        return vfs_setpos(file, next_data, MAX_LFS_FILESIZE);
 }
 
-static bool page_slot_is_data(struct address_space *mapping, pgoff_t index)
+static int __page_hole_offset(struct page *page, unsigned offset)
+{
+       struct bch_page_state *s = bch2_page_state(page);
+       unsigned i;
+
+       if (!s)
+               return 0;
+
+       for (i = offset >> 9; i < PAGE_SECTORS; i++)
+               if (s->s[i].state < SECTOR_DIRTY)
+                       return i << 9;
+
+       return -1;
+}
+
+static loff_t page_hole_offset(struct address_space *mapping, loff_t offset)
 {
+       pgoff_t index = offset >> PAGE_SHIFT;
        struct page *page;
-       bool ret;
+       int pg_offset;
+       loff_t ret = -1;
+
+       page = find_lock_page(mapping, index);
+       if (!page)
+               return offset;
 
-       page = find_lock_entry(mapping, index);
-       if (!page || radix_tree_exception(page))
-               return false;
+       pg_offset = __page_hole_offset(page, offset & (PAGE_SIZE - 1));
+       if (pg_offset >= 0)
+               ret = ((loff_t) index << PAGE_SHIFT) + pg_offset;
 
-       ret = page_is_data(page);
        unlock_page(page);
 
        return ret;
 }
 
-static loff_t bch2_next_pagecache_hole(struct inode *vinode,
+static loff_t bch2_seek_pagecache_hole(struct inode *vinode,
                                       loff_t start_offset,
                                       loff_t end_offset)
 {
        struct address_space *mapping = vinode->i_mapping;
-       pgoff_t index;
+       loff_t offset = start_offset, hole;
+
+       while (offset < end_offset) {
+               hole = page_hole_offset(mapping, offset);
+               if (hole >= 0 && hole <= end_offset)
+                       return max(start_offset, hole);
 
-       for (index = start_offset >> PAGE_SHIFT;
-            index < end_offset >> PAGE_SHIFT;
-            index++)
-               if (!page_slot_is_data(mapping, index))
-                       end_offset = max(start_offset,
-                                        ((loff_t) index) << PAGE_SHIFT);
+               offset += PAGE_SIZE;
+               offset &= PAGE_MASK;
+       }
 
        return end_offset;
 }
@@ -2635,24 +3404,35 @@ static loff_t bch2_seek_hole(struct file *file, u64 offset)
 {
        struct bch_inode_info *inode = file_bch_inode(file);
        struct bch_fs *c = inode->v.i_sb->s_fs_info;
+       struct btree_trans trans;
        struct btree_iter iter;
        struct bkey_s_c k;
+       subvol_inum inum = inode_inum(inode);
        u64 isize, next_hole = MAX_LFS_FILESIZE;
+       u32 snapshot;
        int ret;
 
        isize = i_size_read(&inode->v);
        if (offset >= isize)
                return -ENXIO;
 
-       for_each_btree_key(&iter, c, BTREE_ID_EXTENTS,
-                          POS(inode->v.i_ino, offset >> 9),
-                          BTREE_ITER_WITH_HOLES, k) {
+       bch2_trans_init(&trans, c, 0, 0);
+retry:
+       bch2_trans_begin(&trans);
+
+       ret = bch2_subvolume_get_snapshot(&trans, inum.subvol, &snapshot);
+       if (ret)
+               goto err;
+
+       for_each_btree_key_norestart(&trans, iter, BTREE_ID_extents,
+                          SPOS(inode->v.i_ino, offset >> 9, snapshot),
+                          BTREE_ITER_SLOTS, k, ret) {
                if (k.k->p.inode != inode->v.i_ino) {
-                       next_hole = bch2_next_pagecache_hole(&inode->v,
+                       next_hole = bch2_seek_pagecache_hole(&inode->v,
                                        offset, MAX_LFS_FILESIZE);
                        break;
                } else if (!bkey_extent_is_data(k.k)) {
-                       next_hole = bch2_next_pagecache_hole(&inode->v,
+                       next_hole = bch2_seek_pagecache_hole(&inode->v,
                                        max(offset, bkey_start_offset(k.k) << 9),
                                        k.k->p.offset << 9);
 
@@ -2662,8 +3442,12 @@ static loff_t bch2_seek_hole(struct file *file, u64 offset)
                        offset = max(offset, bkey_start_offset(k.k) << 9);
                }
        }
+       bch2_trans_iter_exit(&trans, &iter);
+err:
+       if (ret == -EINTR)
+               goto retry;
 
-       ret = bch2_btree_iter_unlock(&iter);
+       bch2_trans_exit(&trans);
        if (ret)
                return ret;
 
@@ -2698,18 +3482,23 @@ void bch2_fs_fsio_exit(struct bch_fs *c)
 
 int bch2_fs_fsio_init(struct bch_fs *c)
 {
+       int ret = 0;
+
+       pr_verbose_init(c->opts, "");
+
        if (bioset_init(&c->writepage_bioset,
-                       4, offsetof(struct bch_writepage_io, op.op.wbio.bio),
+                       4, offsetof(struct bch_writepage_io, op.wbio.bio),
                        BIOSET_NEED_BVECS) ||
            bioset_init(&c->dio_read_bioset,
                        4, offsetof(struct dio_read, rbio.bio),
                        BIOSET_NEED_BVECS) ||
            bioset_init(&c->dio_write_bioset,
-                       4, offsetof(struct dio_write, iop.op.wbio.bio),
+                       4, offsetof(struct dio_write, op.wbio.bio),
                        BIOSET_NEED_BVECS))
-               return -ENOMEM;
+               ret = -ENOMEM;
 
-       return 0;
+       pr_verbose_init(c->opts, "ret %i", ret);
+       return ret;
 }
 
 #endif /* NO_BCACHEFS_FS */