]> git.sesse.net Git - bcachefs-tools-debian/blobdiff - libbcachefs/io.c
Update bcachefs sources to bdf6d7c135 fixup! bcachefs: Kill journal buf bloom filter
[bcachefs-tools-debian] / libbcachefs / io.c
index 4d81b6e6e54f79a5510d36941d50ca112810acdd..1ad4c7d77812998a17d4fec011ce645176d49d81 100644 (file)
@@ -7,7 +7,9 @@
  */
 
 #include "bcachefs.h"
+#include "alloc_background.h"
 #include "alloc_foreground.h"
+#include "bkey_buf.h"
 #include "bset.h"
 #include "btree_update.h"
 #include "buckets.h"
 #include "disk_groups.h"
 #include "ec.h"
 #include "error.h"
-#include "extents.h"
+#include "extent_update.h"
+#include "inode.h"
 #include "io.h"
 #include "journal.h"
 #include "keylist.h"
 #include "move.h"
 #include "rebalance.h"
+#include "subvolume.h"
 #include "super.h"
 #include "super-io.h"
 
 #include <linux/blkdev.h>
 #include <linux/random.h>
+#include <linux/sched/mm.h>
 
 #include <trace/events/bcachefs.h>
 
+const char *bch2_blk_status_to_str(blk_status_t status)
+{
+       if (status == BLK_STS_REMOVED)
+               return "device removed";
+       return blk_status_to_str(status);
+}
+
 static bool bch2_target_congested(struct bch_fs *c, u16 target)
 {
        const struct bch_devs_mask *devs;
@@ -44,7 +56,9 @@ static bool bch2_target_congested(struct bch_fs *c, u16 target)
                return false;
 
        rcu_read_lock();
-       devs = bch2_target_to_mask(c, target);
+       devs = bch2_target_to_mask(c, target) ?:
+               &c->rw_devs[BCH_DATA_user];
+
        for_each_set_bit(d, devs->d, BCH_SB_MEMBERS_MAX) {
                ca = rcu_dereference(c->devs[d]);
                if (!ca)
@@ -107,7 +121,7 @@ void bch2_latency_acct(struct bch_dev *ca, u64 submit_time, int rw)
                 * the time:
                 */
                if (abs((int) (old - io_latency)) < (old >> 1) &&
-                   now & ~(~0 << 5))
+                   now & ~(~0U << 5))
                        break;
 
                new = ewma_add(old, io_latency, 5);
@@ -124,9 +138,8 @@ void bch2_bio_free_pages_pool(struct bch_fs *c, struct bio *bio)
 {
        struct bvec_iter_all iter;
        struct bio_vec *bv;
-       unsigned i;
 
-       bio_for_each_segment_all(bv, bio, i, iter)
+       bio_for_each_segment_all(bv, bio, iter)
                if (bv->bv_page != ZERO_PAGE(0))
                        mempool_free(bv->bv_page, &c->bio_bounce_pages);
        bio->bi_vcnt = 0;
@@ -159,7 +172,7 @@ void bch2_bio_alloc_pages_pool(struct bch_fs *c, struct bio *bio,
 
        while (size) {
                struct page *page = __bio_alloc_page_pool(c, &using_mempool);
-               unsigned len = min(PAGE_SIZE, size);
+               unsigned len = min_t(size_t, PAGE_SIZE, size);
 
                BUG_ON(!bio_add_page(bio, page, len, 0));
                size -= len;
@@ -169,6 +182,274 @@ void bch2_bio_alloc_pages_pool(struct bch_fs *c, struct bio *bio,
                mutex_unlock(&c->bio_bounce_pages_lock);
 }
 
+/* Extent update path: */
+
+int bch2_sum_sector_overwrites(struct btree_trans *trans,
+                              struct btree_iter *extent_iter,
+                              struct bkey_i *new,
+                              bool *usage_increasing,
+                              s64 *i_sectors_delta,
+                              s64 *disk_sectors_delta)
+{
+       struct bch_fs *c = trans->c;
+       struct btree_iter iter;
+       struct bkey_s_c old;
+       unsigned new_replicas = bch2_bkey_replicas(c, bkey_i_to_s_c(new));
+       bool new_compressed = bch2_bkey_sectors_compressed(bkey_i_to_s_c(new));
+       int ret = 0;
+
+       *usage_increasing       = false;
+       *i_sectors_delta        = 0;
+       *disk_sectors_delta     = 0;
+
+       bch2_trans_copy_iter(&iter, extent_iter);
+
+       for_each_btree_key_continue_norestart(iter, BTREE_ITER_SLOTS, old, ret) {
+               s64 sectors = min(new->k.p.offset, old.k->p.offset) -
+                       max(bkey_start_offset(&new->k),
+                           bkey_start_offset(old.k));
+
+               *i_sectors_delta += sectors *
+                       (bkey_extent_is_allocation(&new->k) -
+                        bkey_extent_is_allocation(old.k));
+
+               *disk_sectors_delta += sectors * bch2_bkey_nr_ptrs_allocated(bkey_i_to_s_c(new));
+               *disk_sectors_delta -= new->k.p.snapshot == old.k->p.snapshot
+                       ? sectors * bch2_bkey_nr_ptrs_fully_allocated(old)
+                       : 0;
+
+               if (!*usage_increasing &&
+                   (new->k.p.snapshot != old.k->p.snapshot ||
+                    new_replicas > bch2_bkey_replicas(c, old) ||
+                    (!new_compressed && bch2_bkey_sectors_compressed(old))))
+                       *usage_increasing = true;
+
+               if (bkey_cmp(old.k->p, new->k.p) >= 0)
+                       break;
+       }
+
+       bch2_trans_iter_exit(trans, &iter);
+       return ret;
+}
+
+int bch2_extent_update(struct btree_trans *trans,
+                      subvol_inum inum,
+                      struct btree_iter *iter,
+                      struct bkey_i *k,
+                      struct disk_reservation *disk_res,
+                      u64 *journal_seq,
+                      u64 new_i_size,
+                      s64 *i_sectors_delta_total,
+                      bool check_enospc)
+{
+       struct btree_iter inode_iter;
+       struct bch_inode_unpacked inode_u;
+       struct bpos next_pos;
+       bool usage_increasing;
+       s64 i_sectors_delta = 0, disk_sectors_delta = 0;
+       int ret;
+
+       /*
+        * This traverses us the iterator without changing iter->path->pos to
+        * search_key() (which is pos + 1 for extents): we want there to be a
+        * path already traversed at iter->pos because
+        * bch2_trans_extent_update() will use it to attempt extent merging
+        */
+       ret = __bch2_btree_iter_traverse(iter);
+       if (ret)
+               return ret;
+
+       ret = bch2_extent_trim_atomic(trans, iter, k);
+       if (ret)
+               return ret;
+
+       new_i_size = min(k->k.p.offset << 9, new_i_size);
+       next_pos = k->k.p;
+
+       ret = bch2_sum_sector_overwrites(trans, iter, k,
+                       &usage_increasing,
+                       &i_sectors_delta,
+                       &disk_sectors_delta);
+       if (ret)
+               return ret;
+
+       if (disk_res &&
+           disk_sectors_delta > (s64) disk_res->sectors) {
+               ret = bch2_disk_reservation_add(trans->c, disk_res,
+                                       disk_sectors_delta - disk_res->sectors,
+                                       !check_enospc || !usage_increasing
+                                       ? BCH_DISK_RESERVATION_NOFAIL : 0);
+               if (ret)
+                       return ret;
+       }
+
+       ret = bch2_inode_peek(trans, &inode_iter, &inode_u, inum,
+                             BTREE_ITER_INTENT);
+       if (ret)
+               return ret;
+
+       if (!(inode_u.bi_flags & BCH_INODE_I_SIZE_DIRTY) &&
+           new_i_size > inode_u.bi_size)
+               inode_u.bi_size = new_i_size;
+
+       inode_u.bi_sectors += i_sectors_delta;
+
+       ret =   bch2_trans_update(trans, iter, k, 0) ?:
+               bch2_inode_write(trans, &inode_iter, &inode_u) ?:
+               bch2_trans_commit(trans, disk_res, journal_seq,
+                               BTREE_INSERT_NOCHECK_RW|
+                               BTREE_INSERT_NOFAIL);
+       bch2_trans_iter_exit(trans, &inode_iter);
+
+       if (ret)
+               return ret;
+
+       if (i_sectors_delta_total)
+               *i_sectors_delta_total += i_sectors_delta;
+       bch2_btree_iter_set_pos(iter, next_pos);
+
+       return 0;
+}
+
+/*
+ * Returns -EINTR if we had to drop locks:
+ */
+int bch2_fpunch_at(struct btree_trans *trans, struct btree_iter *iter,
+                  subvol_inum inum, u64 end,
+                  s64 *i_sectors_delta)
+{
+       struct bch_fs *c        = trans->c;
+       unsigned max_sectors    = KEY_SIZE_MAX & (~0 << c->block_bits);
+       struct bpos end_pos = POS(inum.inum, end);
+       struct bkey_s_c k;
+       int ret = 0, ret2 = 0;
+       u32 snapshot;
+
+       while (!ret || ret == -EINTR) {
+               struct disk_reservation disk_res =
+                       bch2_disk_reservation_init(c, 0);
+               struct bkey_i delete;
+
+               if (ret)
+                       ret2 = ret;
+
+               bch2_trans_begin(trans);
+
+               ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
+               if (ret)
+                       continue;
+
+               bch2_btree_iter_set_snapshot(iter, snapshot);
+
+               k = bch2_btree_iter_peek(iter);
+               if (bkey_cmp(iter->pos, end_pos) >= 0) {
+                       bch2_btree_iter_set_pos(iter, end_pos);
+                       break;
+               }
+
+               ret = bkey_err(k);
+               if (ret)
+                       continue;
+
+               bkey_init(&delete.k);
+               delete.k.p = iter->pos;
+
+               /* create the biggest key we can */
+               bch2_key_resize(&delete.k, max_sectors);
+               bch2_cut_back(end_pos, &delete);
+
+               ret = bch2_extent_update(trans, inum, iter, &delete,
+                               &disk_res, NULL,
+                               0, i_sectors_delta, false);
+               bch2_disk_reservation_put(c, &disk_res);
+       }
+
+       return ret ?: ret2;
+}
+
+int bch2_fpunch(struct bch_fs *c, subvol_inum inum, u64 start, u64 end,
+               s64 *i_sectors_delta)
+{
+       struct btree_trans trans;
+       struct btree_iter iter;
+       int ret;
+
+       bch2_trans_init(&trans, c, BTREE_ITER_MAX, 1024);
+       bch2_trans_iter_init(&trans, &iter, BTREE_ID_extents,
+                            POS(inum.inum, start),
+                            BTREE_ITER_INTENT);
+
+       ret = bch2_fpunch_at(&trans, &iter, inum, end, i_sectors_delta);
+
+       bch2_trans_iter_exit(&trans, &iter);
+       bch2_trans_exit(&trans);
+
+       return ret == -EINTR ? 0 : ret;
+}
+
+int bch2_write_index_default(struct bch_write_op *op)
+{
+       struct bch_fs *c = op->c;
+       struct bkey_buf sk;
+       struct open_bucket *ec_ob = ec_open_bucket(c, &op->open_buckets);
+       struct keylist *keys = &op->insert_keys;
+       struct bkey_i *k = bch2_keylist_front(keys);
+       struct btree_trans trans;
+       struct btree_iter iter;
+       subvol_inum inum = {
+               .subvol = op->subvol,
+               .inum   = k->k.p.inode,
+       };
+       int ret;
+
+       BUG_ON(!inum.subvol);
+
+       bch2_bkey_buf_init(&sk);
+       bch2_trans_init(&trans, c, BTREE_ITER_MAX, 1024);
+
+       do {
+               bch2_trans_begin(&trans);
+
+               k = bch2_keylist_front(keys);
+               bch2_bkey_buf_copy(&sk, c, k);
+
+               ret = bch2_subvolume_get_snapshot(&trans, inum.subvol,
+                                                 &sk.k->k.p.snapshot);
+               if (ret == -EINTR)
+                       continue;
+               if (ret)
+                       break;
+
+               bch2_trans_iter_init(&trans, &iter, BTREE_ID_extents,
+                                    bkey_start_pos(&sk.k->k),
+                                    BTREE_ITER_SLOTS|BTREE_ITER_INTENT);
+
+               ret = bch2_extent_update(&trans, inum, &iter, sk.k,
+                                        &op->res, op_journal_seq(op),
+                                        op->new_i_size, &op->i_sectors_delta,
+                                        op->flags & BCH_WRITE_CHECK_ENOSPC);
+               bch2_trans_iter_exit(&trans, &iter);
+
+               if (ret == -EINTR)
+                       continue;
+               if (ret)
+                       break;
+
+               if (ec_ob)
+                       bch2_ob_add_backpointer(c, ec_ob, &sk.k->k);
+
+               if (bkey_cmp(iter.pos, k->k.p) >= 0)
+                       bch2_keylist_pop_front(&op->insert_keys);
+               else
+                       bch2_cut_front(iter.pos, k);
+       } while (!bch2_keylist_empty(keys));
+
+       bch2_trans_exit(&trans);
+       bch2_bkey_buf_exit(&sk, c);
+
+       return ret;
+}
+
 /* Writes */
 
 void bch2_submit_wbio_replicas(struct bch_write_bio *wbio, struct bch_fs *c,
@@ -207,13 +488,11 @@ void bch2_submit_wbio_replicas(struct bch_write_bio *wbio, struct bch_fs *c,
 
                n->c                    = c;
                n->dev                  = ptr->dev;
-               n->have_ioref           = bch2_dev_get_ioref(ca, WRITE);
+               n->have_ioref           = bch2_dev_get_ioref(ca,
+                                       type == BCH_DATA_btree ? READ : WRITE);
                n->submit_time          = local_clock();
                n->bio.bi_iter.bi_sector = ptr->offset;
 
-               if (!journal_flushes_device(ca))
-                       n->bio.bi_opf |= REQ_FUA;
-
                if (likely(n->have_ioref)) {
                        this_cpu_add(ca->io_done->sectors[WRITE][type],
                                     bio_sectors(&n->bio));
@@ -237,58 +516,19 @@ static void bch2_write_done(struct closure *cl)
        if (!op->error && (op->flags & BCH_WRITE_FLUSH))
                op->error = bch2_journal_error(&c->journal);
 
-       if (!(op->flags & BCH_WRITE_NOPUT_RESERVATION))
-               bch2_disk_reservation_put(c, &op->res);
+       bch2_disk_reservation_put(c, &op->res);
        percpu_ref_put(&c->writes);
        bch2_keylist_free(&op->insert_keys, op->inline_keys);
 
        bch2_time_stats_update(&c->times[BCH_TIME_data_write], op->start_time);
 
-       closure_return(cl);
-}
-
-int bch2_write_index_default(struct bch_write_op *op)
-{
-       struct bch_fs *c = op->c;
-       struct btree_trans trans;
-       struct btree_iter *iter;
-       struct keylist *keys = &op->insert_keys;
-       int ret;
-
-       BUG_ON(bch2_keylist_empty(keys));
-       bch2_verify_keylist_sorted(keys);
-
-       bch2_trans_init(&trans, c, BTREE_ITER_MAX, 256);
-
-       iter = bch2_trans_get_iter(&trans, BTREE_ID_EXTENTS,
-                                  bkey_start_pos(&bch2_keylist_front(keys)->k),
-                                  BTREE_ITER_INTENT);
-
-       do {
-               BKEY_PADDED(k) split;
-
-               bkey_copy(&split.k, bch2_keylist_front(keys));
-
-               bch2_extent_trim_atomic(&split.k, iter);
-
-               bch2_trans_update(&trans,
-                                 BTREE_INSERT_ENTRY(iter, &split.k));
-
-               ret = bch2_trans_commit(&trans, &op->res, op_journal_seq(op),
-                                       BTREE_INSERT_NOFAIL|
-                                       BTREE_INSERT_USE_RESERVE);
-               if (ret)
-                       break;
-
-               if (bkey_cmp(iter->pos, bch2_keylist_front(keys)->k.p) < 0)
-                       bch2_cut_front(iter->pos, bch2_keylist_front(keys));
-               else
-                       bch2_keylist_pop_front(keys);
-       } while (!bch2_keylist_empty(keys));
-
-       bch2_trans_exit(&trans);
-
-       return ret;
+       if (op->end_io) {
+               EBUG_ON(cl->parent);
+               closure_debug_destroy(cl);
+               op->end_io(op);
+       } else {
+               closure_return(cl);
+       }
 }
 
 /**
@@ -305,16 +545,19 @@ static void __bch2_write_index(struct bch_write_op *op)
 
        for (src = keys->keys; src != keys->top; src = n) {
                n = bkey_next(src);
-               bkey_copy(dst, src);
 
-               bch2_bkey_drop_ptrs(bkey_i_to_s(dst), ptr,
-                       test_bit(ptr->dev, op->failed.d));
+               if (bkey_extent_is_direct_data(&src->k)) {
+                       bch2_bkey_drop_ptrs(bkey_i_to_s(src), ptr,
+                                           test_bit(ptr->dev, op->failed.d));
 
-               if (!bch2_bkey_nr_ptrs(bkey_i_to_s_c(dst))) {
-                       ret = -EIO;
-                       goto err;
+                       if (!bch2_bkey_nr_ptrs(bkey_i_to_s_c(src))) {
+                               ret = -EIO;
+                               goto err;
+                       }
                }
 
+               if (dst != src)
+                       memmove_u64s_down(dst, src, src->u64s);
                dst = bkey_next(dst);
        }
 
@@ -325,19 +568,26 @@ static void __bch2_write_index(struct bch_write_op *op)
         * particularly want to plumb io_opts all the way through the btree
         * update stack right now
         */
-       for_each_keylist_key(keys, k)
+       for_each_keylist_key(keys, k) {
                bch2_rebalance_add_key(c, bkey_i_to_s_c(k), &op->opts);
 
+               if (bch2_bkey_is_incompressible(bkey_i_to_s_c(k)))
+                       bch2_check_set_feature(op->c, BCH_FEATURE_incompressible);
+
+       }
+
        if (!bch2_keylist_empty(keys)) {
                u64 sectors_start = keylist_sectors(keys);
                int ret = op->index_update_fn(op);
 
+               BUG_ON(ret == -EINTR);
                BUG_ON(keylist_sectors(keys) && !ret);
 
                op->written += sectors_start - keylist_sectors(keys);
 
                if (ret) {
-                       __bcache_io_error(c, "btree IO error %i", ret);
+                       bch_err_inum_ratelimited(c, op->pos.inode,
+                               "write error %i from btree update", ret);
                        op->error = ret;
                }
        }
@@ -361,7 +611,9 @@ static void bch2_write_index(struct closure *cl)
 
        __bch2_write_index(op);
 
-       if (!op->error && (op->flags & BCH_WRITE_FLUSH)) {
+       if (!(op->flags & BCH_WRITE_DONE)) {
+               continue_at(cl, __bch2_write, index_update_wq(op));
+       } else if (!op->error && (op->flags & BCH_WRITE_FLUSH)) {
                bch2_journal_flush_seq_async(&c->journal,
                                             *op_journal_seq(op),
                                             cl);
@@ -380,7 +632,11 @@ static void bch2_write_endio(struct bio *bio)
        struct bch_fs *c                = wbio->c;
        struct bch_dev *ca              = bch_dev_bkey_exists(c, wbio->dev);
 
-       if (bch2_dev_io_err_on(bio->bi_status, ca, "data write"))
+       if (bch2_dev_inum_io_err_on(bio->bi_status, ca,
+                                   op->pos.inode,
+                                   op->pos.offset - bio_sectors(bio), /* XXX definitely wrong */
+                                   "data write error: %s",
+                              bch2_blk_status_to_str(bio->bi_status)))
                set_bit(wbio->dev, op->failed.d);
 
        if (wbio->have_ioref) {
@@ -396,8 +652,10 @@ static void bch2_write_endio(struct bio *bio)
 
        if (parent)
                bio_endio(&parent->bio);
-       else
+       else if (!(op->flags & BCH_WRITE_SKIP_CLOSURE_PUT))
                closure_put(cl);
+       else
+               continue_at_nobarrier(cl, bch2_write_index, index_update_wq(op));
 }
 
 static void init_append_extent(struct bch_write_op *op,
@@ -406,31 +664,22 @@ static void init_append_extent(struct bch_write_op *op,
                               struct bch_extent_crc_unpacked crc)
 {
        struct bch_fs *c = op->c;
-       struct bkey_i_extent *e = bkey_extent_init(op->insert_keys.top);
-       struct extent_ptr_decoded p = { .crc = crc };
-       struct open_bucket *ob;
-       unsigned i;
+       struct bkey_i_extent *e;
 
        op->pos.offset += crc.uncompressed_size;
+
+       e = bkey_extent_init(op->insert_keys.top);
        e->k.p          = op->pos;
        e->k.size       = crc.uncompressed_size;
        e->k.version    = version;
 
-       BUG_ON(crc.compressed_size > wp->sectors_free);
-       wp->sectors_free -= crc.compressed_size;
-
-       open_bucket_for_each(c, &wp->ptrs, ob, i) {
-               struct bch_dev *ca = bch_dev_bkey_exists(c, ob->ptr.dev);
+       if (crc.csum_type ||
+           crc.compression_type ||
+           crc.nonce)
+               bch2_extent_crc_append(&e->k_i, crc);
 
-               p.ptr = ob->ptr;
-               p.ptr.cached = !ca->mi.durability ||
-                       (op->flags & BCH_WRITE_CACHED) != 0;
-               p.ptr.offset += ca->mi.bucket_size - ob->sectors_free;
-               bch2_extent_ptr_decoded_append(e, &p);
-
-               BUG_ON(crc.compressed_size > ob->sectors_free);
-               ob->sectors_free -= crc.compressed_size;
-       }
+       bch2_alloc_sectors_append_ptrs(c, wp, &e->k_i, crc.compressed_size,
+                                      op->flags & BCH_WRITE_CACHED);
 
        bch2_keylist_push(&op->insert_keys);
 }
@@ -445,7 +694,12 @@ static struct bio *bch2_write_bio_alloc(struct bch_fs *c,
        struct bio *bio;
        unsigned output_available =
                min(wp->sectors_free << 9, src->bi_iter.bi_size);
-       unsigned pages = DIV_ROUND_UP(output_available, PAGE_SIZE);
+       unsigned pages = DIV_ROUND_UP(output_available +
+                                     (buf
+                                      ? ((unsigned long) buf & (PAGE_SIZE - 1))
+                                      : 0), PAGE_SIZE);
+
+       pages = min(pages, BIO_MAX_VECS);
 
        bio = bio_alloc_bioset(GFP_NOIO, pages, &c->bio_write);
        wbio                    = wbio_init(bio);
@@ -466,7 +720,7 @@ static struct bio *bch2_write_bio_alloc(struct bch_fs *c,
         */
        bch2_bio_alloc_pages_pool(c, bio,
                                  min_t(unsigned, output_available,
-                                       c->sb.encoded_extent_max << 9));
+                                       c->opts.encoded_extent_max));
 
        if (bio->bi_iter.bi_size < output_available)
                *page_alloc_failed =
@@ -510,6 +764,7 @@ static int bch2_write_decrypt(struct bch_write_op *op)
        struct bch_fs *c = op->c;
        struct nonce nonce = extent_nonce(op->version, op->crc);
        struct bch_csum csum;
+       int ret;
 
        if (!bch2_csum_type_is_encryption(op->crc.csum_type))
                return 0;
@@ -524,10 +779,10 @@ static int bch2_write_decrypt(struct bch_write_op *op)
        if (bch2_crc_cmp(op->crc.csum, csum))
                return -EIO;
 
-       bch2_encrypt_bio(c, op->crc.csum_type, nonce, &op->wbio.bio);
+       ret = bch2_encrypt_bio(c, op->crc.csum_type, nonce, &op->wbio.bio);
        op->crc.csum_type = 0;
        op->crc.csum = (struct bch_csum) { 0, 0 };
-       return 0;
+       return ret;
 }
 
 static enum prep_encoded_ret {
@@ -548,8 +803,9 @@ static enum prep_encoded_ret {
        /* Can we just write the entire extent as is? */
        if (op->crc.uncompressed_size == op->crc.live_size &&
            op->crc.compressed_size <= wp->sectors_free &&
-           op->crc.compression_type == op->compression_type) {
-               if (!op->crc.compression_type &&
+           (op->crc.compression_type == op->compression_type ||
+            op->incompressible)) {
+               if (!crc_is_compressed(op->crc) &&
                    op->csum_type != op->crc.csum_type &&
                    bch2_write_rechecksum(c, op, op->csum_type))
                        return PREP_ENCODED_CHECKSUM_ERR;
@@ -561,7 +817,7 @@ static enum prep_encoded_ret {
         * If the data is compressed and we couldn't write the entire extent as
         * is, we have to decompress it:
         */
-       if (op->crc.compression_type) {
+       if (crc_is_compressed(op->crc)) {
                struct bch_csum csum;
 
                if (bch2_write_decrypt(op))
@@ -604,15 +860,13 @@ static enum prep_encoded_ret {
        return PREP_ENCODED_OK;
 }
 
-static int bch2_write_extent(struct bch_write_op *op, struct write_point *wp)
+static int bch2_write_extent(struct bch_write_op *op, struct write_point *wp,
+                            struct bio **_dst)
 {
        struct bch_fs *c = op->c;
        struct bio *src = &op->wbio.bio, *dst = src;
        struct bvec_iter saved_iter;
-       struct bkey_i *key_to_write;
        void *ec_buf;
-       unsigned key_to_write_offset = op->insert_keys.top_p -
-               op->insert_keys.keys_p;
        unsigned total_output = 0, total_input = 0;
        bool bounce = false;
        bool page_alloc_failed = false;
@@ -631,6 +885,7 @@ static int bch2_write_extent(struct bch_write_op *op, struct write_point *wp)
        case PREP_ENCODED_CHECKSUM_ERR:
                goto csum_err;
        case PREP_ENCODED_DO_WRITE:
+               /* XXX look for bug here */
                if (ec_buf) {
                        dst = bch2_write_bio_alloc(c, wp, src,
                                                   &page_alloc_failed,
@@ -663,8 +918,8 @@ static int bch2_write_extent(struct bch_write_op *op, struct write_point *wp)
                size_t dst_len, src_len;
 
                if (page_alloc_failed &&
-                   bio_sectors(dst) < wp->sectors_free &&
-                   bio_sectors(dst) < c->sb.encoded_extent_max)
+                   dst->bi_iter.bi_size  < (wp->sectors_free << 9) &&
+                   dst->bi_iter.bi_size < c->opts.encoded_extent_max)
                        break;
 
                BUG_ON(op->compression_type &&
@@ -672,17 +927,19 @@ static int bch2_write_extent(struct bch_write_op *op, struct write_point *wp)
                       bch2_csum_type_is_encryption(op->crc.csum_type));
                BUG_ON(op->compression_type && !bounce);
 
-               crc.compression_type = op->compression_type
-                       ?  bch2_bio_compress(c, dst, &dst_len, src, &src_len,
-                                            op->compression_type)
+               crc.compression_type = op->incompressible
+                       ? BCH_COMPRESSION_TYPE_incompressible
+                       : op->compression_type
+                       ? bch2_bio_compress(c, dst, &dst_len, src, &src_len,
+                                           op->compression_type)
                        : 0;
-               if (!crc.compression_type) {
+               if (!crc_is_compressed(crc)) {
                        dst_len = min(dst->bi_iter.bi_size, src->bi_iter.bi_size);
                        dst_len = min_t(unsigned, dst_len, wp->sectors_free << 9);
 
                        if (op->csum_type)
                                dst_len = min_t(unsigned, dst_len,
-                                               c->sb.encoded_extent_max << 9);
+                                               c->opts.encoded_extent_max);
 
                        if (bounce) {
                                swap(dst->bi_iter.bi_size, dst_len);
@@ -697,7 +954,7 @@ static int bch2_write_extent(struct bch_write_op *op, struct write_point *wp)
 
                if (bch2_csum_type_is_encryption(op->csum_type)) {
                        if (bversion_zero(version)) {
-                               version.lo = atomic64_inc_return(&c->key_version) + 1;
+                               version.lo = atomic64_inc_return(&c->key_version);
                        } else {
                                crc.nonce = op->nonce;
                                op->nonce += src_len >> 9;
@@ -705,7 +962,7 @@ static int bch2_write_extent(struct bch_write_op *op, struct write_point *wp)
                }
 
                if ((op->flags & BCH_WRITE_DATA_ENCODED) &&
-                   !crc.compression_type &&
+                   !crc_is_compressed(crc) &&
                    bch2_csum_type_is_encryption(op->crc.csum_type) ==
                    bch2_csum_type_is_encryption(op->csum_type)) {
                        /*
@@ -740,8 +997,11 @@ static int bch2_write_extent(struct bch_write_op *op, struct write_point *wp)
                        crc.live_size           = src_len >> 9;
 
                        swap(dst->bi_iter.bi_size, dst_len);
-                       bch2_encrypt_bio(c, op->csum_type,
-                                        extent_nonce(version, crc), dst);
+                       ret = bch2_encrypt_bio(c, op->csum_type,
+                                              extent_nonce(version, crc), dst);
+                       if (ret)
+                               goto err;
+
                        crc.csum = bch2_checksum_bio(c, op->csum_type,
                                         extent_nonce(version, crc), dst);
                        crc.csum_type = op->csum_type;
@@ -779,22 +1039,7 @@ static int bch2_write_extent(struct bch_write_op *op, struct write_point *wp)
 
        dst->bi_iter.bi_size = total_output;
 do_write:
-       /* might have done a realloc... */
-
-       key_to_write = (void *) (op->insert_keys.keys_p + key_to_write_offset);
-
-       bch2_ec_add_backpointer(c, wp,
-                               bkey_start_pos(&key_to_write->k),
-                               total_input >> 9);
-
-       dst->bi_end_io  = bch2_write_endio;
-       dst->bi_private = &op->cl;
-       bio_set_op_attrs(dst, REQ_OP_WRITE, 0);
-
-       closure_get(dst->bi_private);
-
-       bch2_submit_wbio_replicas(to_wbio(dst), c, BCH_DATA_USER,
-                                 key_to_write);
+       *_dst = dst;
        return more;
 csum_err:
        bch_err(c, "error verifying existing checksum while "
@@ -814,11 +1059,20 @@ static void __bch2_write(struct closure *cl)
        struct bch_write_op *op = container_of(cl, struct bch_write_op, cl);
        struct bch_fs *c = op->c;
        struct write_point *wp;
+       struct bio *bio = NULL;
+       bool skip_put = true;
+       unsigned nofs_flags;
        int ret;
+
+       nofs_flags = memalloc_nofs_save();
 again:
        memset(&op->failed, 0, sizeof(op->failed));
 
        do {
+               struct bkey_i *key_to_write;
+               unsigned key_to_write_offset = op->insert_keys.top_p -
+                       op->insert_keys.keys_p;
+
                /* +1 for possible cache device: */
                if (op->open_buckets.nr + op->nr_replicas + 1 >
                    ARRAY_SIZE(op->open_buckets.v))
@@ -830,16 +1084,28 @@ again:
                                        BKEY_EXTENT_U64s_MAX))
                        goto flush_io;
 
+               if ((op->flags & BCH_WRITE_FROM_INTERNAL) &&
+                   percpu_ref_is_dying(&c->writes)) {
+                       ret = -EROFS;
+                       goto err;
+               }
+
+               /*
+                * The copygc thread is now global, which means it's no longer
+                * freeing up space on specific disks, which means that
+                * allocations for specific disks may hang arbitrarily long:
+                */
                wp = bch2_alloc_sectors_start(c,
                        op->target,
-                       op->opts.erasure_code,
+                       op->opts.erasure_code && !(op->flags & BCH_WRITE_CACHED),
                        op->write_point,
                        &op->devs_have,
                        op->nr_replicas,
                        op->nr_replicas_required,
                        op->alloc_reserve,
                        op->flags,
-                       (op->flags & BCH_WRITE_ALLOC_NOWAIT) ? NULL : cl);
+                       (op->flags & (BCH_WRITE_ALLOC_NOWAIT|
+                                     BCH_WRITE_ONLY_SPECIFIED_DEVS)) ? NULL : cl);
                EBUG_ON(!wp);
 
                if (unlikely(IS_ERR(wp))) {
@@ -851,39 +1117,133 @@ again:
                        goto flush_io;
                }
 
-               ret = bch2_write_extent(op, wp);
+               /*
+                * It's possible for the allocator to fail, put us on the
+                * freelist waitlist, and then succeed in one of various retry
+                * paths: if that happens, we need to disable the skip_put
+                * optimization because otherwise there won't necessarily be a
+                * barrier before we free the bch_write_op:
+                */
+               if (atomic_read(&cl->remaining) & CLOSURE_WAITING)
+                       skip_put = false;
 
                bch2_open_bucket_get(c, wp, &op->open_buckets);
+               ret = bch2_write_extent(op, wp, &bio);
                bch2_alloc_sectors_done(c, wp);
 
                if (ret < 0)
                        goto err;
+
+               if (ret) {
+                       skip_put = false;
+               } else {
+                       /*
+                        * for the skip_put optimization this has to be set
+                        * before we submit the bio:
+                        */
+                       op->flags |= BCH_WRITE_DONE;
+               }
+
+               bio->bi_end_io  = bch2_write_endio;
+               bio->bi_private = &op->cl;
+               bio->bi_opf |= REQ_OP_WRITE;
+
+               if (!skip_put)
+                       closure_get(bio->bi_private);
+               else
+                       op->flags |= BCH_WRITE_SKIP_CLOSURE_PUT;
+
+               key_to_write = (void *) (op->insert_keys.keys_p +
+                                        key_to_write_offset);
+
+               bch2_submit_wbio_replicas(to_wbio(bio), c, BCH_DATA_user,
+                                         key_to_write);
        } while (ret);
 
-       continue_at(cl, bch2_write_index, index_update_wq(op));
+       if (!skip_put)
+               continue_at(cl, bch2_write_index, index_update_wq(op));
+out:
+       memalloc_nofs_restore(nofs_flags);
        return;
 err:
        op->error = ret;
+       op->flags |= BCH_WRITE_DONE;
 
-       continue_at(cl, !bch2_keylist_empty(&op->insert_keys)
-                   ? bch2_write_index
-                   : bch2_write_done, index_update_wq(op));
-       return;
+       continue_at(cl, bch2_write_index, index_update_wq(op));
+       goto out;
 flush_io:
+       /*
+        * If the write can't all be submitted at once, we generally want to
+        * block synchronously as that signals backpressure to the caller.
+        *
+        * However, if we're running out of a workqueue, we can't block here
+        * because we'll be blocking other work items from completing:
+        */
+       if (current->flags & PF_WQ_WORKER) {
+               continue_at(cl, bch2_write_index, index_update_wq(op));
+               goto out;
+       }
+
        closure_sync(cl);
 
        if (!bch2_keylist_empty(&op->insert_keys)) {
                __bch2_write_index(op);
 
                if (op->error) {
+                       op->flags |= BCH_WRITE_DONE;
                        continue_at_nobarrier(cl, bch2_write_done, NULL);
-                       return;
+                       goto out;
                }
        }
 
        goto again;
 }
 
+static void bch2_write_data_inline(struct bch_write_op *op, unsigned data_len)
+{
+       struct closure *cl = &op->cl;
+       struct bio *bio = &op->wbio.bio;
+       struct bvec_iter iter;
+       struct bkey_i_inline_data *id;
+       unsigned sectors;
+       int ret;
+
+       bch2_check_set_feature(op->c, BCH_FEATURE_inline_data);
+
+       ret = bch2_keylist_realloc(&op->insert_keys, op->inline_keys,
+                                  ARRAY_SIZE(op->inline_keys),
+                                  BKEY_U64s + DIV_ROUND_UP(data_len, 8));
+       if (ret) {
+               op->error = ret;
+               goto err;
+       }
+
+       sectors = bio_sectors(bio);
+       op->pos.offset += sectors;
+
+       id = bkey_inline_data_init(op->insert_keys.top);
+       id->k.p         = op->pos;
+       id->k.version   = op->version;
+       id->k.size      = sectors;
+
+       iter = bio->bi_iter;
+       iter.bi_size = data_len;
+       memcpy_from_bio(id->v.data, bio, iter);
+
+       while (data_len & 7)
+               id->v.data[data_len++] = '\0';
+       set_bkey_val_bytes(&id->k, data_len);
+       bch2_keylist_push(&op->insert_keys);
+
+       op->flags |= BCH_WRITE_WROTE_DATA_INLINE;
+       op->flags |= BCH_WRITE_DONE;
+
+       continue_at_nobarrier(cl, bch2_write_index, NULL);
+       return;
+err:
+       bch2_write_done(&op->cl);
+}
+
 /**
  * bch_write - handle a write to a cache device or flash only volume
  *
@@ -903,30 +1263,55 @@ flush_io:
 void bch2_write(struct closure *cl)
 {
        struct bch_write_op *op = container_of(cl, struct bch_write_op, cl);
+       struct bio *bio = &op->wbio.bio;
        struct bch_fs *c = op->c;
+       unsigned data_len;
 
        BUG_ON(!op->nr_replicas);
        BUG_ON(!op->write_point.v);
        BUG_ON(!bkey_cmp(op->pos, POS_MAX));
 
        op->start_time = local_clock();
-
        bch2_keylist_init(&op->insert_keys, op->inline_keys);
-       wbio_init(&op->wbio.bio)->put_bio = false;
+       wbio_init(bio)->put_bio = false;
+
+       if (bio->bi_iter.bi_size & (c->opts.block_size - 1)) {
+               bch_err_inum_ratelimited(c, op->pos.inode,
+                                        "misaligned write");
+               op->error = -EIO;
+               goto err;
+       }
 
        if (c->opts.nochanges ||
            !percpu_ref_tryget(&c->writes)) {
-               __bcache_io_error(c, "read only");
                op->error = -EROFS;
-               if (!(op->flags & BCH_WRITE_NOPUT_RESERVATION))
-                       bch2_disk_reservation_put(c, &op->res);
-               closure_return(cl);
-               return;
+               goto err;
        }
 
-       bch2_increment_clock(c, bio_sectors(&op->wbio.bio), WRITE);
+       this_cpu_add(c->counters[BCH_COUNTER_io_write], bio_sectors(bio));
+       bch2_increment_clock(c, bio_sectors(bio), WRITE);
+
+       data_len = min_t(u64, bio->bi_iter.bi_size,
+                        op->new_i_size - (op->pos.offset << 9));
+
+       if (c->opts.inline_data &&
+           data_len <= min(block_bytes(c) / 2, 1024U)) {
+               bch2_write_data_inline(op, data_len);
+               return;
+       }
 
        continue_at_nobarrier(cl, __bch2_write, NULL);
+       return;
+err:
+       bch2_disk_reservation_put(c, &op->res);
+
+       if (op->end_io) {
+               EBUG_ON(cl->parent);
+               closure_debug_destroy(cl);
+               op->end_io(op);
+       } else {
+               closure_return(cl);
+       }
 }
 
 /* Cache promotion on read */
@@ -954,17 +1339,13 @@ static inline bool should_promote(struct bch_fs *c, struct bkey_s_c k,
                                  struct bch_io_opts opts,
                                  unsigned flags)
 {
-       if (!bkey_extent_is_data(k.k))
-               return false;
-
        if (!(flags & BCH_READ_MAY_PROMOTE))
                return false;
 
        if (!opts.promote_target)
                return false;
 
-       if (bch2_extent_has_target(c, bkey_s_c_to_extent(k),
-                                  opts.promote_target))
+       if (bch2_bkey_has_target(c, k, opts.promote_target))
                return false;
 
        if (bch2_target_congested(c, opts.promote_target)) {
@@ -1022,12 +1403,13 @@ static void promote_start(struct promote_op *op, struct bch_read_bio *rbio)
        bch2_migrate_read_done(&op->write, rbio);
 
        closure_init(cl, NULL);
-       closure_call(&op->write.op.cl, bch2_write, c->wq, cl);
+       closure_call(&op->write.op.cl, bch2_write, c->btree_update_wq, cl);
        closure_return_with_destructor(cl, promote_done);
 }
 
-noinline
 static struct promote_op *__promote_alloc(struct bch_fs *c,
+                                         enum btree_id btree_id,
+                                         struct bkey_s_c k,
                                          struct bpos pos,
                                          struct extent_ptr_decoded *pick,
                                          struct bch_io_opts opts,
@@ -1082,9 +1464,10 @@ static struct promote_op *__promote_alloc(struct bch_fs *c,
                        opts,
                        DATA_PROMOTE,
                        (struct data_opts) {
-                               .target = opts.promote_target
+                               .target         = opts.promote_target,
+                               .nr_replicas    = 1,
                        },
-                       bkey_s_c_null);
+                       btree_id, k);
        BUG_ON(ret);
 
        return op;
@@ -1098,7 +1481,8 @@ err:
        return NULL;
 }
 
-static inline struct promote_op *promote_alloc(struct bch_fs *c,
+noinline
+static struct promote_op *promote_alloc(struct bch_fs *c,
                                               struct bvec_iter iter,
                                               struct bkey_s_c k,
                                               struct extent_ptr_decoded *pick,
@@ -1121,7 +1505,11 @@ static inline struct promote_op *promote_alloc(struct bch_fs *c,
        if (!should_promote(c, k, pos, opts, flags))
                return NULL;
 
-       promote = __promote_alloc(c, pos, pick, opts, sectors, rbio);
+       promote = __promote_alloc(c,
+                                 k.k->type == KEY_TYPE_reflink_v
+                                 ? BTREE_ID_reflink
+                                 : BTREE_ID_extents,
+                                 k, pos, pick, opts, sectors, rbio);
        if (!promote)
                return NULL;
 
@@ -1187,121 +1575,76 @@ static inline struct bch_read_bio *bch2_rbio_free(struct bch_read_bio *rbio)
        return rbio;
 }
 
+/*
+ * Only called on a top level bch_read_bio to complete an entire read request,
+ * not a split:
+ */
 static void bch2_rbio_done(struct bch_read_bio *rbio)
 {
-       bch2_time_stats_update(&rbio->c->times[BCH_TIME_data_read],
-                              rbio->start_time);
+       if (rbio->start_time)
+               bch2_time_stats_update(&rbio->c->times[BCH_TIME_data_read],
+                                      rbio->start_time);
        bio_endio(&rbio->bio);
 }
 
 static void bch2_read_retry_nodecode(struct bch_fs *c, struct bch_read_bio *rbio,
-                                    struct bvec_iter bvec_iter, u64 inode,
+                                    struct bvec_iter bvec_iter,
                                     struct bch_io_failures *failed,
                                     unsigned flags)
 {
        struct btree_trans trans;
-       struct btree_iter *iter;
-       BKEY_PADDED(k) tmp;
+       struct btree_iter iter;
+       struct bkey_buf sk;
        struct bkey_s_c k;
        int ret;
 
        flags &= ~BCH_READ_LAST_FRAGMENT;
+       flags |= BCH_READ_MUST_CLONE;
 
+       bch2_bkey_buf_init(&sk);
        bch2_trans_init(&trans, c, 0, 0);
 
-       iter = bch2_trans_get_iter(&trans, BTREE_ID_EXTENTS,
-                                  rbio->pos, BTREE_ITER_SLOTS);
+       bch2_trans_iter_init(&trans, &iter, rbio->data_btree,
+                            rbio->read_pos, BTREE_ITER_SLOTS);
 retry:
        rbio->bio.bi_status = 0;
 
-       k = bch2_btree_iter_peek_slot(iter);
+       k = bch2_btree_iter_peek_slot(&iter);
        if (bkey_err(k))
                goto err;
 
-       bkey_reassemble(&tmp.k, k);
-       k = bkey_i_to_s_c(&tmp.k);
+       bch2_bkey_buf_reassemble(&sk, c, k);
+       k = bkey_i_to_s_c(sk.k);
        bch2_trans_unlock(&trans);
 
-       if (!bkey_extent_is_data(k.k) ||
-           !bch2_extent_matches_ptr(c, bkey_i_to_s_c_extent(&tmp.k),
-                                    rbio->pick.ptr,
-                                    rbio->pos.offset -
-                                    rbio->pick.crc.offset)) {
+       if (!bch2_bkey_matches_ptr(c, k,
+                                  rbio->pick.ptr,
+                                  rbio->data_pos.offset -
+                                  rbio->pick.crc.offset)) {
                /* extent we wanted to read no longer exists: */
                rbio->hole = true;
                goto out;
        }
 
-       ret = __bch2_read_extent(c, rbio, bvec_iter, k, failed, flags);
+       ret = __bch2_read_extent(&trans, rbio, bvec_iter,
+                                rbio->read_pos,
+                                rbio->data_btree,
+                                k, 0, failed, flags);
        if (ret == READ_RETRY)
                goto retry;
        if (ret)
                goto err;
 out:
        bch2_rbio_done(rbio);
+       bch2_trans_iter_exit(&trans, &iter);
        bch2_trans_exit(&trans);
+       bch2_bkey_buf_exit(&sk, c);
        return;
 err:
        rbio->bio.bi_status = BLK_STS_IOERR;
        goto out;
 }
 
-static void bch2_read_retry(struct bch_fs *c, struct bch_read_bio *rbio,
-                           struct bvec_iter bvec_iter, u64 inode,
-                           struct bch_io_failures *failed, unsigned flags)
-{
-       struct btree_trans trans;
-       struct btree_iter *iter;
-       struct bkey_s_c k;
-       int ret;
-
-       bch2_trans_init(&trans, c, 0, 0);
-
-       flags &= ~BCH_READ_LAST_FRAGMENT;
-       flags |= BCH_READ_MUST_CLONE;
-retry:
-       for_each_btree_key(&trans, iter, BTREE_ID_EXTENTS,
-                          POS(inode, bvec_iter.bi_sector),
-                          BTREE_ITER_SLOTS, k, ret) {
-               BKEY_PADDED(k) tmp;
-               unsigned bytes;
-
-               bkey_reassemble(&tmp.k, k);
-               k = bkey_i_to_s_c(&tmp.k);
-               bch2_trans_unlock(&trans);
-
-               bytes = min_t(unsigned, bvec_iter.bi_size,
-                             (k.k->p.offset - bvec_iter.bi_sector) << 9);
-               swap(bvec_iter.bi_size, bytes);
-
-               ret = __bch2_read_extent(c, rbio, bvec_iter, k, failed, flags);
-               switch (ret) {
-               case READ_RETRY:
-                       goto retry;
-               case READ_ERR:
-                       goto err;
-               };
-
-               if (bytes == bvec_iter.bi_size)
-                       goto out;
-
-               swap(bvec_iter.bi_size, bytes);
-               bio_advance_iter(&rbio->bio, &bvec_iter, bytes);
-       }
-
-       /*
-        * If we get here, it better have been because there was an error
-        * reading a btree node
-        */
-       BUG_ON(!ret);
-       __bcache_io_error(c, "btree IO error: %i", ret);
-err:
-       rbio->bio.bi_status = BLK_STS_IOERR;
-out:
-       bch2_trans_exit(&trans);
-       bch2_rbio_done(rbio);
-}
-
 static void bch2_rbio_retry(struct work_struct *work)
 {
        struct bch_read_bio *rbio =
@@ -1309,7 +1652,10 @@ static void bch2_rbio_retry(struct work_struct *work)
        struct bch_fs *c        = rbio->c;
        struct bvec_iter iter   = rbio->bvec_iter;
        unsigned flags          = rbio->flags;
-       u64 inode               = rbio->pos.inode;
+       subvol_inum inum = {
+               .subvol = rbio->subvol,
+               .inum   = rbio->read_pos.inode,
+       };
        struct bch_io_failures failed = { .nr = 0 };
 
        trace_read_retry(&rbio->bio);
@@ -1324,10 +1670,14 @@ static void bch2_rbio_retry(struct work_struct *work)
        flags |= BCH_READ_IN_RETRY;
        flags &= ~BCH_READ_MAY_PROMOTE;
 
-       if (flags & BCH_READ_NODECODE)
-               bch2_read_retry_nodecode(c, rbio, iter, inode, &failed, flags);
-       else
-               bch2_read_retry(c, rbio, iter, inode, &failed, flags);
+       if (flags & BCH_READ_NODECODE) {
+               bch2_read_retry_nodecode(c, rbio, iter, &failed, flags);
+       } else {
+               flags &= ~BCH_READ_LAST_FRAGMENT;
+               flags |= BCH_READ_MUST_CLONE;
+
+               __bch2_read(c, rbio, iter, inum, &failed, flags);
+       }
 }
 
 static void bch2_rbio_error(struct bch_read_bio *rbio, int retry,
@@ -1349,76 +1699,68 @@ static void bch2_rbio_error(struct bch_read_bio *rbio, int retry,
        }
 }
 
-static void bch2_rbio_narrow_crcs(struct bch_read_bio *rbio)
+static int __bch2_rbio_narrow_crcs(struct btree_trans *trans,
+                                  struct bch_read_bio *rbio)
 {
        struct bch_fs *c = rbio->c;
-       struct btree_trans trans;
-       struct btree_iter *iter;
-       struct bkey_s_c k;
-       struct bkey_i_extent *e;
-       BKEY_PADDED(k) new;
+       u64 data_offset = rbio->data_pos.offset - rbio->pick.crc.offset;
        struct bch_extent_crc_unpacked new_crc;
-       u64 data_offset = rbio->pos.offset - rbio->pick.crc.offset;
-       int ret;
-
-       if (rbio->pick.crc.compression_type)
-               return;
-
-       bch2_trans_init(&trans, c, 0, 0);
-retry:
-       bch2_trans_begin(&trans);
+       struct btree_iter iter;
+       struct bkey_i *new;
+       struct bkey_s_c k;
+       int ret = 0;
 
-       iter = bch2_trans_get_iter(&trans, BTREE_ID_EXTENTS, rbio->pos,
-                                  BTREE_ITER_INTENT);
-       k = bch2_btree_iter_peek(iter);
-       if (IS_ERR_OR_NULL(k.k))
-               goto out;
+       if (crc_is_compressed(rbio->pick.crc))
+               return 0;
 
-       if (!bkey_extent_is_data(k.k))
+       bch2_trans_iter_init(trans, &iter, rbio->data_btree, rbio->data_pos,
+                            BTREE_ITER_SLOTS|BTREE_ITER_INTENT);
+       k = bch2_btree_iter_peek_slot(&iter);
+       if ((ret = bkey_err(k)))
                goto out;
 
-       bkey_reassemble(&new.k, k);
-       e = bkey_i_to_extent(&new.k);
-
-       if (!bch2_extent_matches_ptr(c, extent_i_to_s_c(e),
-                                    rbio->pick.ptr, data_offset) ||
-           bversion_cmp(e->k.version, rbio->version))
+       if (bversion_cmp(k.k->version, rbio->version) ||
+           !bch2_bkey_matches_ptr(c, k, rbio->pick.ptr, data_offset))
                goto out;
 
        /* Extent was merged? */
-       if (bkey_start_offset(&e->k) < data_offset ||
-           e->k.p.offset > data_offset + rbio->pick.crc.uncompressed_size)
+       if (bkey_start_offset(k.k) < data_offset ||
+           k.k->p.offset > data_offset + rbio->pick.crc.uncompressed_size)
                goto out;
 
        if (bch2_rechecksum_bio(c, &rbio->bio, rbio->version,
                        rbio->pick.crc, NULL, &new_crc,
-                       bkey_start_offset(&e->k) - data_offset, e->k.size,
+                       bkey_start_offset(k.k) - data_offset, k.k->size,
                        rbio->pick.crc.csum_type)) {
                bch_err(c, "error verifying existing checksum while narrowing checksum (memory corruption?)");
+               ret = 0;
                goto out;
        }
 
-       if (!bch2_extent_narrow_crcs(e, new_crc))
+       /*
+        * going to be temporarily appending another checksum entry:
+        */
+       new = bch2_trans_kmalloc(trans, bkey_bytes(k.k) +
+                                sizeof(struct bch_extent_crc128));
+       if ((ret = PTR_ERR_OR_ZERO(new)))
+               goto out;
+
+       bkey_reassemble(new, k);
+
+       if (!bch2_bkey_narrow_crcs(new, new_crc))
                goto out;
 
-       bch2_trans_update(&trans, BTREE_INSERT_ENTRY(iter, &e->k_i));
-       ret = bch2_trans_commit(&trans, NULL, NULL,
-                               BTREE_INSERT_ATOMIC|
-                               BTREE_INSERT_NOFAIL|
-                               BTREE_INSERT_NOWAIT);
-       if (ret == -EINTR)
-               goto retry;
+       ret = bch2_trans_update(trans, &iter, new,
+                               BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
 out:
-       bch2_trans_exit(&trans);
+       bch2_trans_iter_exit(trans, &iter);
+       return ret;
 }
 
-static bool should_narrow_crcs(struct bkey_s_c k,
-                              struct extent_ptr_decoded *pick,
-                              unsigned flags)
+static noinline void bch2_rbio_narrow_crcs(struct bch_read_bio *rbio)
 {
-       return !(flags & BCH_READ_IN_RETRY) &&
-               bkey_extent_is_data(k.k) &&
-               bch2_can_narrow_extent_crcs(bkey_s_c_to_extent(k), pick->crc);
+       bch2_trans_do(rbio->c, NULL, NULL, BTREE_INSERT_NOFAIL,
+                     __bch2_rbio_narrow_crcs(&trans, rbio));
 }
 
 /* Inner part that may run in process context */
@@ -1433,7 +1775,11 @@ static void __bch2_read_endio(struct work_struct *work)
        struct bvec_iter dst_iter = rbio->bvec_iter;
        struct bch_extent_crc_unpacked crc = rbio->pick.crc;
        struct nonce nonce = extent_nonce(rbio->version, crc);
+       unsigned nofs_flags;
        struct bch_csum csum;
+       int ret;
+
+       nofs_flags = memalloc_nofs_save();
 
        /* Reset iterator for checksumming and copying bounced data: */
        if (rbio->bounce) {
@@ -1448,6 +1794,13 @@ static void __bch2_read_endio(struct work_struct *work)
        if (bch2_crc_cmp(csum, rbio->pick.crc.csum))
                goto csum_err;
 
+       /*
+        * XXX
+        * We need to rework the narrow_crcs path to deliver the read completion
+        * first, and then punt to a different workqueue, otherwise we're
+        * holding up reads while doing btree updates which is bad for memory
+        * reclaim.
+        */
        if (unlikely(rbio->narrow_crcs))
                bch2_rbio_narrow_crcs(rbio);
 
@@ -1455,11 +1808,14 @@ static void __bch2_read_endio(struct work_struct *work)
                goto nodecode;
 
        /* Adjust crc to point to subset of data we want: */
-       crc.offset     += rbio->bvec_iter.bi_sector - rbio->pos.offset;
+       crc.offset     += rbio->offset_into_extent;
        crc.live_size   = bvec_iter_sectors(rbio->bvec_iter);
 
-       if (crc.compression_type != BCH_COMPRESSION_NONE) {
-               bch2_encrypt_bio(c, crc.csum_type, nonce, src);
+       if (crc_is_compressed(crc)) {
+               ret = bch2_encrypt_bio(c, crc.csum_type, nonce, src);
+               if (ret)
+                       goto decrypt_err;
+
                if (bch2_bio_uncompress(c, src, dst, dst_iter, crc))
                        goto decompression_err;
        } else {
@@ -1470,7 +1826,9 @@ static void __bch2_read_endio(struct work_struct *work)
                BUG_ON(src->bi_iter.bi_size < dst_iter.bi_size);
                src->bi_iter.bi_size = dst_iter.bi_size;
 
-               bch2_encrypt_bio(c, crc.csum_type, nonce, src);
+               ret = bch2_encrypt_bio(c, crc.csum_type, nonce, src);
+               if (ret)
+                       goto decrypt_err;
 
                if (rbio->bounce) {
                        struct bvec_iter src_iter = src->bi_iter;
@@ -1483,7 +1841,10 @@ static void __bch2_read_endio(struct work_struct *work)
                 * Re encrypt data we decrypted, so it's consistent with
                 * rbio->crc:
                 */
-               bch2_encrypt_bio(c, crc.csum_type, nonce, src);
+               ret = bch2_encrypt_bio(c, crc.csum_type, nonce, src);
+               if (ret)
+                       goto decrypt_err;
+
                promote_start(rbio->promote, rbio);
                rbio->promote = NULL;
        }
@@ -1492,6 +1853,8 @@ nodecode:
                rbio = bch2_rbio_free(rbio);
                bch2_rbio_done(rbio);
        }
+out:
+       memalloc_nofs_restore(nofs_flags);
        return;
 csum_err:
        /*
@@ -1502,22 +1865,25 @@ csum_err:
        if (!rbio->bounce && (rbio->flags & BCH_READ_USER_MAPPED)) {
                rbio->flags |= BCH_READ_MUST_BOUNCE;
                bch2_rbio_error(rbio, READ_RETRY, BLK_STS_IOERR);
-               return;
+               goto out;
        }
 
-       bch2_dev_io_error(ca,
-               "data checksum error, inode %llu offset %llu: expected %0llx:%0llx got %0llx:%0llx (type %u)",
-               rbio->pos.inode, (u64) rbio->bvec_iter.bi_sector,
+       bch2_dev_inum_io_error(ca, rbio->read_pos.inode, (u64) rbio->bvec_iter.bi_sector,
+               "data checksum error: expected %0llx:%0llx got %0llx:%0llx (type %u)",
                rbio->pick.crc.csum.hi, rbio->pick.crc.csum.lo,
                csum.hi, csum.lo, crc.csum_type);
        bch2_rbio_error(rbio, READ_RETRY_AVOID, BLK_STS_IOERR);
-       return;
+       goto out;
 decompression_err:
-       __bcache_io_error(c, "decompression error, inode %llu offset %llu",
-                         rbio->pos.inode,
-                         (u64) rbio->bvec_iter.bi_sector);
+       bch_err_inum_ratelimited(c, rbio->read_pos.inode,
+                                "decompression error");
        bch2_rbio_error(rbio, READ_ERR, BLK_STS_IOERR);
-       return;
+       goto out;
+decrypt_err:
+       bch_err_inum_ratelimited(c, rbio->read_pos.inode,
+                                "decrypt error");
+       bch2_rbio_error(rbio, READ_ERR, BLK_STS_IOERR);
+       goto out;
 }
 
 static void bch2_read_endio(struct bio *bio)
@@ -1537,14 +1903,17 @@ static void bch2_read_endio(struct bio *bio)
        if (!rbio->split)
                rbio->bio.bi_end_io = rbio->end_io;
 
-       if (bch2_dev_io_err_on(bio->bi_status, ca, "data read")) {
+       if (bch2_dev_inum_io_err_on(bio->bi_status, ca,
+                                   rbio->read_pos.inode,
+                                   rbio->read_pos.offset,
+                                   "data read error: %s",
+                              bch2_blk_status_to_str(bio->bi_status))) {
                bch2_rbio_error(rbio, READ_RETRY_AVOID, bio->bi_status);
                return;
        }
 
-       if (rbio->pick.ptr.cached &&
-           (((rbio->flags & BCH_READ_RETRY_IF_STALE) && race_fault()) ||
-            ptr_stale(ca, &rbio->pick.ptr))) {
+       if (((rbio->flags & BCH_READ_RETRY_IF_STALE) && race_fault()) ||
+           ptr_stale(ca, &rbio->pick.ptr)) {
                atomic_long_inc(&c->read_realloc_races);
 
                if (rbio->flags & BCH_READ_RETRY_IF_STALE)
@@ -1555,7 +1924,7 @@ static void bch2_read_endio(struct bio *bio)
        }
 
        if (rbio->narrow_crcs ||
-           rbio->pick.crc.compression_type ||
+           crc_is_compressed(rbio->pick.crc) ||
            bch2_csum_type_is_encryption(rbio->pick.crc.csum_type))
                context = RBIO_CONTEXT_UNBOUND, wq = system_unbound_wq;
        else if (rbio->pick.crc.csum_type)
@@ -1564,18 +1933,107 @@ static void bch2_read_endio(struct bio *bio)
        bch2_rbio_punt(rbio, __bch2_read_endio, context, wq);
 }
 
-int __bch2_read_extent(struct bch_fs *c, struct bch_read_bio *orig,
-                      struct bvec_iter iter, struct bkey_s_c k,
+int __bch2_read_indirect_extent(struct btree_trans *trans,
+                               unsigned *offset_into_extent,
+                               struct bkey_buf *orig_k)
+{
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       u64 reflink_offset;
+       int ret;
+
+       reflink_offset = le64_to_cpu(bkey_i_to_reflink_p(orig_k->k)->v.idx) +
+               *offset_into_extent;
+
+       bch2_trans_iter_init(trans, &iter, BTREE_ID_reflink,
+                            POS(0, reflink_offset),
+                            BTREE_ITER_SLOTS);
+       k = bch2_btree_iter_peek_slot(&iter);
+       ret = bkey_err(k);
+       if (ret)
+               goto err;
+
+       if (k.k->type != KEY_TYPE_reflink_v &&
+           k.k->type != KEY_TYPE_indirect_inline_data) {
+               bch_err_inum_ratelimited(trans->c, orig_k->k->k.p.inode,
+                       "%llu len %u points to nonexistent indirect extent %llu",
+                       orig_k->k->k.p.offset,
+                       orig_k->k->k.size,
+                       reflink_offset);
+               bch2_inconsistent_error(trans->c);
+               ret = -EIO;
+               goto err;
+       }
+
+       *offset_into_extent = iter.pos.offset - bkey_start_offset(k.k);
+       bch2_bkey_buf_reassemble(orig_k, trans->c, k);
+err:
+       bch2_trans_iter_exit(trans, &iter);
+       return ret;
+}
+
+static noinline void read_from_stale_dirty_pointer(struct btree_trans *trans,
+                                                  struct bkey_s_c k,
+                                                  struct bch_extent_ptr ptr)
+{
+       struct bch_fs *c = trans->c;
+       struct bch_dev *ca = bch_dev_bkey_exists(c, ptr.dev);
+       struct btree_iter iter;
+       struct printbuf buf = PRINTBUF;
+       int ret;
+
+       bch2_trans_iter_init(trans, &iter, BTREE_ID_alloc,
+                            PTR_BUCKET_POS(c, &ptr),
+                            BTREE_ITER_CACHED);
+
+       pr_buf(&buf, "Attempting to read from stale dirty pointer:");
+       pr_indent_push(&buf, 2);
+       pr_newline(&buf);
+
+       bch2_bkey_val_to_text(&buf, c, k);
+       pr_newline(&buf);
+
+       pr_buf(&buf, "memory gen: %u", *bucket_gen(ca, iter.pos.offset));
+
+       ret = lockrestart_do(trans, bkey_err(k = bch2_btree_iter_peek_slot(&iter)));
+       if (!ret) {
+               pr_newline(&buf);
+               bch2_bkey_val_to_text(&buf, c, k);
+       }
+
+       bch2_fs_inconsistent(c, "%s", buf.buf);
+
+       bch2_trans_iter_exit(trans, &iter);
+       printbuf_exit(&buf);
+}
+
+int __bch2_read_extent(struct btree_trans *trans, struct bch_read_bio *orig,
+                      struct bvec_iter iter, struct bpos read_pos,
+                      enum btree_id data_btree, struct bkey_s_c k,
+                      unsigned offset_into_extent,
                       struct bch_io_failures *failed, unsigned flags)
 {
+       struct bch_fs *c = trans->c;
        struct extent_ptr_decoded pick;
        struct bch_read_bio *rbio = NULL;
-       struct bch_dev *ca;
+       struct bch_dev *ca = NULL;
        struct promote_op *promote = NULL;
        bool bounce = false, read_full = false, narrow_crcs = false;
-       struct bpos pos = bkey_start_pos(k.k);
+       struct bpos data_pos = bkey_start_pos(k.k);
        int pick_ret;
 
+       if (bkey_extent_is_inline_data(k.k)) {
+               unsigned bytes = min_t(unsigned, iter.bi_size,
+                                      bkey_inline_data_bytes(k.k));
+
+               swap(iter.bi_size, bytes);
+               memcpy_to_bio(&orig->bio, iter, bkey_inline_data_p(k));
+               swap(iter.bi_size, bytes);
+               bio_advance_iter(&orig->bio, &iter, bytes);
+               zero_fill_bio_iter(&orig->bio, iter);
+               goto out_read_done;
+       }
+retry_pick:
        pick_ret = bch2_bkey_pick_read_device(c, k, failed, &pick);
 
        /* hole or reservation - just zero fill: */
@@ -1583,12 +2041,32 @@ int __bch2_read_extent(struct bch_fs *c, struct bch_read_bio *orig,
                goto hole;
 
        if (pick_ret < 0) {
-               __bcache_io_error(c, "no device to read from");
+               bch_err_inum_ratelimited(c, k.k->p.inode,
+                                        "no device to read from");
                goto err;
        }
 
-       if (pick_ret > 0)
-               ca = bch_dev_bkey_exists(c, pick.ptr.dev);
+       ca = bch_dev_bkey_exists(c, pick.ptr.dev);
+
+       /*
+        * Stale dirty pointers are treated as IO errors, but @failed isn't
+        * allocated unless we're in the retry path - so if we're not in the
+        * retry path, don't check here, it'll be caught in bch2_read_endio()
+        * and we'll end up in the retry path:
+        */
+       if ((flags & BCH_READ_IN_RETRY) &&
+           !pick.ptr.cached &&
+           unlikely(ptr_stale(ca, &pick.ptr))) {
+               read_from_stale_dirty_pointer(trans, k, pick.ptr);
+               bch2_mark_io_failure(failed, &pick);
+               goto retry_pick;
+       }
+
+       /*
+        * Unlock the iterator while the btree node's lock is still in
+        * cache, before doing the IO:
+        */
+       bch2_trans_unlock(trans);
 
        if (flags & BCH_READ_NODECODE) {
                /*
@@ -1598,25 +2076,24 @@ int __bch2_read_extent(struct bch_fs *c, struct bch_read_bio *orig,
                if (pick.crc.compressed_size > orig->bio.bi_vcnt * PAGE_SECTORS)
                        goto hole;
 
-               iter.bi_sector  = pos.offset;
                iter.bi_size    = pick.crc.compressed_size << 9;
-               goto noclone;
+               goto get_bio;
        }
 
        if (!(flags & BCH_READ_LAST_FRAGMENT) ||
            bio_flagged(&orig->bio, BIO_CHAIN))
                flags |= BCH_READ_MUST_CLONE;
 
-       narrow_crcs = should_narrow_crcs(k, &pick, flags);
+       narrow_crcs = !(flags & BCH_READ_IN_RETRY) &&
+               bch2_can_narrow_extent_crcs(k, pick.crc);
 
        if (narrow_crcs && (flags & BCH_READ_USER_MAPPED))
                flags |= BCH_READ_MUST_BOUNCE;
 
-       EBUG_ON(bkey_start_offset(k.k) > iter.bi_sector ||
-               k.k->p.offset < bvec_iter_end_sector(iter));
+       EBUG_ON(offset_into_extent + bvec_iter_sectors(iter) > k.k->size);
 
-       if (pick.crc.compression_type != BCH_COMPRESSION_NONE ||
-           (pick.crc.csum_type != BCH_CSUM_NONE &&
+       if (crc_is_compressed(pick.crc) ||
+           (pick.crc.csum_type != BCH_CSUM_none &&
             (bvec_iter_sectors(iter) != pick.crc.uncompressed_size ||
              (bch2_csum_type_is_encryption(pick.crc.csum_type) &&
               (flags & BCH_READ_USER_MAPPED)) ||
@@ -1625,26 +2102,29 @@ int __bch2_read_extent(struct bch_fs *c, struct bch_read_bio *orig,
                bounce = true;
        }
 
-       promote = promote_alloc(c, iter, k, &pick, orig->opts, flags,
-                               &rbio, &bounce, &read_full);
+       if (orig->opts.promote_target)
+               promote = promote_alloc(c, iter, k, &pick, orig->opts, flags,
+                                       &rbio, &bounce, &read_full);
 
        if (!read_full) {
-               EBUG_ON(pick.crc.compression_type);
+               EBUG_ON(crc_is_compressed(pick.crc));
                EBUG_ON(pick.crc.csum_type &&
                        (bvec_iter_sectors(iter) != pick.crc.uncompressed_size ||
                         bvec_iter_sectors(iter) != pick.crc.live_size ||
                         pick.crc.offset ||
-                        iter.bi_sector != pos.offset));
+                        offset_into_extent));
 
+               data_pos.offset += offset_into_extent;
                pick.ptr.offset += pick.crc.offset +
-                       (iter.bi_sector - pos.offset);
+                       offset_into_extent;
+               offset_into_extent              = 0;
                pick.crc.compressed_size        = bvec_iter_sectors(iter);
                pick.crc.uncompressed_size      = bvec_iter_sectors(iter);
                pick.crc.offset                 = 0;
                pick.crc.live_size              = bvec_iter_sectors(iter);
-               pos.offset                      = iter.bi_sector;
+               offset_into_extent              = 0;
        }
-
+get_bio:
        if (rbio) {
                /*
                 * promote already allocated bounce rbio:
@@ -1652,7 +2132,7 @@ int __bch2_read_extent(struct bch_fs *c, struct bch_read_bio *orig,
                 * data in the write path, but we're not going to use it all
                 * here:
                 */
-               BUG_ON(rbio->bio.bi_iter.bi_size <
+               EBUG_ON(rbio->bio.bi_iter.bi_size <
                       pick.crc.compressed_size << 9);
                rbio->bio.bi_iter.bi_size =
                        pick.crc.compressed_size << 9;
@@ -1682,13 +2162,12 @@ int __bch2_read_extent(struct bch_fs *c, struct bch_read_bio *orig,
                rbio->bio.bi_iter = iter;
                rbio->split     = true;
        } else {
-noclone:
                rbio = orig;
                rbio->bio.bi_iter = iter;
-               BUG_ON(bio_flagged(&rbio->bio, BIO_CHAIN));
+               EBUG_ON(bio_flagged(&rbio->bio, BIO_CHAIN));
        }
 
-       BUG_ON(bio_sectors(&rbio->bio) != pick.crc.compressed_size);
+       EBUG_ON(bio_sectors(&rbio->bio) != pick.crc.compressed_size);
 
        rbio->c                 = c;
        rbio->submit_time       = local_clock();
@@ -1697,15 +2176,20 @@ noclone:
        else
                rbio->end_io    = orig->bio.bi_end_io;
        rbio->bvec_iter         = iter;
+       rbio->offset_into_extent= offset_into_extent;
        rbio->flags             = flags;
        rbio->have_ioref        = pick_ret > 0 && bch2_dev_get_ioref(ca, READ);
        rbio->narrow_crcs       = narrow_crcs;
        rbio->hole              = 0;
        rbio->retry             = 0;
        rbio->context           = 0;
+       /* XXX: only initialize this if needed */
        rbio->devs_have         = bch2_bkey_devs(k);
        rbio->pick              = pick;
-       rbio->pos               = pos;
+       rbio->subvol            = orig->subvol;
+       rbio->read_pos          = read_pos;
+       rbio->data_btree        = data_btree;
+       rbio->data_pos          = data_pos;
        rbio->version           = k.k->version;
        rbio->promote           = promote;
        INIT_WORK(&rbio->work, NULL);
@@ -1717,25 +2201,31 @@ noclone:
        if (rbio->bounce)
                trace_read_bounce(&rbio->bio);
 
+       this_cpu_add(c->counters[BCH_COUNTER_io_read], bio_sectors(&rbio->bio));
        bch2_increment_clock(c, bio_sectors(&rbio->bio), READ);
 
-       percpu_down_read(&c->mark_lock);
-       bucket_io_clock_reset(c, ca, PTR_BUCKET_NR(ca, &pick.ptr), READ);
-       percpu_up_read(&c->mark_lock);
+       /*
+        * If it's being moved internally, we don't want to flag it as a cache
+        * hit:
+        */
+       if (pick.ptr.cached && !(flags & BCH_READ_NODECODE))
+               bch2_bucket_io_time_reset(trans, pick.ptr.dev,
+                       PTR_BUCKET_NR(ca, &pick.ptr), READ);
 
-       if (likely(!(flags & (BCH_READ_IN_RETRY|BCH_READ_LAST_FRAGMENT)))) {
+       if (!(flags & (BCH_READ_IN_RETRY|BCH_READ_LAST_FRAGMENT))) {
                bio_inc_remaining(&orig->bio);
                trace_read_split(&orig->bio);
        }
 
        if (!rbio->pick.idx) {
                if (!rbio->have_ioref) {
-                       __bcache_io_error(c, "no device to read from");
+                       bch_err_inum_ratelimited(c, k.k->p.inode,
+                                                "no device to read from");
                        bch2_rbio_error(rbio, READ_RETRY_AVOID, BLK_STS_IOERR);
                        goto out;
                }
 
-               this_cpu_add(ca->io_done->sectors[READ][BCH_DATA_USER],
+               this_cpu_add(ca->io_done->sectors[READ][BCH_DATA_user],
                             bio_sectors(&rbio->bio));
                bio_set_dev(&rbio->bio, ca->disk_sb.bdev);
 
@@ -1770,6 +2260,9 @@ out:
                        ret = READ_RETRY;
                }
 
+               if (!ret)
+                       goto out_read_done;
+
                return ret;
        }
 
@@ -1796,64 +2289,109 @@ out_read_done:
        return 0;
 }
 
-void bch2_read(struct bch_fs *c, struct bch_read_bio *rbio, u64 inode)
+void __bch2_read(struct bch_fs *c, struct bch_read_bio *rbio,
+                struct bvec_iter bvec_iter, subvol_inum inum,
+                struct bch_io_failures *failed, unsigned flags)
 {
        struct btree_trans trans;
-       struct btree_iter *iter;
+       struct btree_iter iter;
+       struct bkey_buf sk;
        struct bkey_s_c k;
-       unsigned flags = BCH_READ_RETRY_IF_STALE|
-               BCH_READ_MAY_PROMOTE|
-               BCH_READ_USER_MAPPED;
+       u32 snapshot;
        int ret;
 
+       BUG_ON(flags & BCH_READ_NODECODE);
+
+       bch2_bkey_buf_init(&sk);
        bch2_trans_init(&trans, c, 0, 0);
+retry:
+       bch2_trans_begin(&trans);
+       iter = (struct btree_iter) { NULL };
 
-       BUG_ON(rbio->_state);
-       BUG_ON(flags & BCH_READ_NODECODE);
-       BUG_ON(flags & BCH_READ_IN_RETRY);
+       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, bvec_iter.bi_sector, snapshot),
+                            BTREE_ITER_SLOTS);
+       while (1) {
+               unsigned bytes, sectors, offset_into_extent;
+               enum btree_id data_btree = BTREE_ID_extents;
 
-       rbio->c = c;
-       rbio->start_time = local_clock();
+               /*
+                * 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;
+               }
 
-       for_each_btree_key(&trans, iter, BTREE_ID_EXTENTS,
-                          POS(inode, rbio->bio.bi_iter.bi_sector),
-                          BTREE_ITER_SLOTS, k, ret) {
-               BKEY_PADDED(k) tmp;
-               unsigned bytes;
+               bch2_btree_iter_set_pos(&iter,
+                               POS(inum.inum, bvec_iter.bi_sector));
+
+               k = bch2_btree_iter_peek_slot(&iter);
+               ret = bkey_err(k);
+               if (ret)
+                       break;
+
+               offset_into_extent = iter.pos.offset -
+                       bkey_start_offset(k.k);
+               sectors = k.k->size - offset_into_extent;
+
+               bch2_bkey_buf_reassemble(&sk, c, k);
+
+               ret = bch2_read_indirect_extent(&trans, &data_btree,
+                                       &offset_into_extent, &sk);
+               if (ret)
+                       break;
+
+               k = bkey_i_to_s_c(sk.k);
 
                /*
-                * Unlock the iterator while the btree node's lock is still in
-                * cache, before doing the IO:
+                * With indirect extents, the amount of data to read is the min
+                * of the original extent and the indirect extent:
                 */
-               bkey_reassemble(&tmp.k, k);
-               k = bkey_i_to_s_c(&tmp.k);
-               bch2_trans_unlock(&trans);
+               sectors = min(sectors, k.k->size - offset_into_extent);
 
-               bytes = min_t(unsigned, rbio->bio.bi_iter.bi_size,
-                             (k.k->p.offset - rbio->bio.bi_iter.bi_sector) << 9);
-               swap(rbio->bio.bi_iter.bi_size, bytes);
+               bytes = min(sectors, bvec_iter_sectors(bvec_iter)) << 9;
+               swap(bvec_iter.bi_size, bytes);
 
-               if (rbio->bio.bi_iter.bi_size == bytes)
+               if (bvec_iter.bi_size == bytes)
                        flags |= BCH_READ_LAST_FRAGMENT;
 
-               bch2_read_extent(c, rbio, k, flags);
+               ret = __bch2_read_extent(&trans, rbio, bvec_iter, iter.pos,
+                                        data_btree, k,
+                                        offset_into_extent, failed, flags);
+               if (ret)
+                       break;
 
                if (flags & BCH_READ_LAST_FRAGMENT)
-                       return;
+                       break;
+
+               swap(bvec_iter.bi_size, bytes);
+               bio_advance_iter(&rbio->bio, &bvec_iter, bytes);
 
-               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 we get here, it better have been because there was an error
-        * reading a btree node
-        */
-       BUG_ON(!ret);
-       bcache_io_error(c, &rbio->bio, "btree IO error: %i", ret);
+       if (ret == -EINTR || ret == READ_RETRY || ret == READ_RETRY_AVOID)
+               goto retry;
 
        bch2_trans_exit(&trans);
-       bch2_rbio_done(rbio);
+       bch2_bkey_buf_exit(&sk, c);
+
+       if (ret) {
+               bch_err_inum_ratelimited(c, inum.inum,
+                                        "read error %i from btree lookup", ret);
+               rbio->bio.bi_status = BLK_STS_IOERR;
+               bch2_rbio_done(rbio);
+       }
 }
 
 void bch2_fs_io_exit(struct bch_fs *c)
@@ -1877,8 +2415,8 @@ int bch2_fs_io_init(struct bch_fs *c)
            mempool_init_page_pool(&c->bio_bounce_pages,
                                   max_t(unsigned,
                                         c->opts.btree_node_size,
-                                        c->sb.encoded_extent_max) /
-                                  PAGE_SECTORS, 0) ||
+                                        c->opts.encoded_extent_max) /
+                                  PAGE_SIZE, 0) ||
            rhashtable_init(&c->promote_table, &bch_promote_params))
                return -ENOMEM;