]> 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 21087d1193dcf9143be1fa7f947b16d1073d9bc0..1ad4c7d77812998a17d4fec011ce645176d49d81 100644 (file)
@@ -9,7 +9,7 @@
 #include "bcachefs.h"
 #include "alloc_background.h"
 #include "alloc_foreground.h"
-#include "bkey_on_stack.h"
+#include "bkey_buf.h"
 #include "bset.h"
 #include "btree_update.h"
 #include "buckets.h"
@@ -27,6 +27,7 @@
 #include "keylist.h"
 #include "move.h"
 #include "rebalance.h"
+#include "subvolume.h"
 #include "super.h"
 #include "super-io.h"
 
@@ -120,7 +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);
@@ -183,255 +184,268 @@ void bch2_bio_alloc_pages_pool(struct bch_fs *c, struct bio *bio,
 
 /* Extent update path: */
 
-static int sum_sector_overwrites(struct btree_trans *trans,
-                                struct btree_iter *extent_iter,
-                                struct bkey_i *new,
-                                bool may_allocate,
-                                bool *maybe_extending,
-                                s64 *delta)
+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 btree_iter *iter;
+       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;
 
-       *maybe_extending = true;
-       *delta = 0;
+       *usage_increasing       = false;
+       *i_sectors_delta        = 0;
+       *disk_sectors_delta     = 0;
 
-       iter = bch2_trans_copy_iter(trans, extent_iter);
-       if (IS_ERR(iter))
-               return PTR_ERR(iter);
+       bch2_trans_copy_iter(&iter, extent_iter);
 
-       for_each_btree_key_continue(iter, BTREE_ITER_SLOTS, old, ret) {
-               if (!may_allocate &&
-                   bch2_bkey_nr_ptrs_fully_allocated(old) <
-                   bch2_bkey_nr_ptrs_allocated(bkey_i_to_s_c(new))) {
-                       ret = -ENOSPC;
-                       break;
-               }
+       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));
 
-               *delta += (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));
 
-               if (bkey_cmp(old.k->p, new->k.p) >= 0) {
-                       /*
-                        * Check if there's already data above where we're
-                        * going to be writing to - this means we're definitely
-                        * not extending the file:
-                        *
-                        * Note that it's not sufficient to check if there's
-                        * data up to the sector offset we're going to be
-                        * writing to, because i_size could be up to one block
-                        * less:
-                        */
-                       if (!bkey_cmp(old.k->p, new->k.p))
-                               old = bch2_btree_iter_next(iter);
+               *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 (old.k && !bkey_err(old) &&
-                           old.k->p.inode == extent_iter->pos.inode &&
-                           bkey_extent_is_data(old.k))
-                               *maybe_extending = false;
+               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_put(trans, iter);
+       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)
+                      s64 *i_sectors_delta_total,
+                      bool check_enospc)
 {
-       /* this must live until after bch2_trans_commit(): */
-       struct bkey_inode_buf inode_p;
-       bool extending = false;
-       s64 delta = 0;
+       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;
 
-       ret = bch2_extent_trim_atomic(k, iter);
+       /*
+        * 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 = sum_sector_overwrites(trans, iter, k,
-                       disk_res && disk_res->sectors != 0,
-                       &extending, &delta);
+       ret = bch2_extent_trim_atomic(trans, iter, k);
        if (ret)
                return ret;
 
-       new_i_size = extending
-               ? min(k->k.p.offset << 9, new_i_size)
-               : 0;
-
-       if (delta || new_i_size) {
-               struct btree_iter *inode_iter;
-               struct bch_inode_unpacked inode_u;
+       new_i_size = min(k->k.p.offset << 9, new_i_size);
+       next_pos = k->k.p;
 
-               inode_iter = bch2_inode_peek(trans, &inode_u,
-                               k->k.p.inode, BTREE_ITER_INTENT);
-               if (IS_ERR(inode_iter))
-                       return PTR_ERR(inode_iter);
+       ret = bch2_sum_sector_overwrites(trans, iter, k,
+                       &usage_increasing,
+                       &i_sectors_delta,
+                       &disk_sectors_delta);
+       if (ret)
+               return ret;
 
-               /*
-                * XXX:
-                * writeback can race a bit with truncate, because truncate
-                * first updates the inode then truncates the pagecache. This is
-                * ugly, but lets us preserve the invariant that the in memory
-                * i_size is always >= the on disk i_size.
-                *
-               BUG_ON(new_i_size > inode_u.bi_size &&
-                      (inode_u.bi_flags & BCH_INODE_I_SIZE_DIRTY));
-                */
-               BUG_ON(new_i_size > inode_u.bi_size && !extending);
+       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;
+       }
 
-               if (!(inode_u.bi_flags & BCH_INODE_I_SIZE_DIRTY) &&
-                   new_i_size > inode_u.bi_size)
-                       inode_u.bi_size = new_i_size;
-               else
-                       new_i_size = 0;
+       ret = bch2_inode_peek(trans, &inode_iter, &inode_u, inum,
+                             BTREE_ITER_INTENT);
+       if (ret)
+               return ret;
 
-               inode_u.bi_sectors += delta;
+       if (!(inode_u.bi_flags & BCH_INODE_I_SIZE_DIRTY) &&
+           new_i_size > inode_u.bi_size)
+               inode_u.bi_size = new_i_size;
 
-               if (delta || new_i_size) {
-                       bch2_inode_pack(trans->c, &inode_p, &inode_u);
-                       bch2_trans_update(trans, inode_iter,
-                                         &inode_p.inode.k_i, 0);
-               }
+       inode_u.bi_sectors += i_sectors_delta;
 
-               bch2_trans_iter_put(trans, inode_iter);
-       }
+       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);
 
-       bch2_trans_update(trans, iter, k, 0);
+       if (ret)
+               return ret;
 
-       ret = bch2_trans_commit(trans, disk_res, journal_seq,
-                               BTREE_INSERT_NOCHECK_RW|
-                               BTREE_INSERT_NOFAIL|
-                               BTREE_INSERT_USE_RESERVE);
-       if (!ret && i_sectors_delta)
-               *i_sectors_delta += delta;
+       if (i_sectors_delta_total)
+               *i_sectors_delta_total += i_sectors_delta;
+       bch2_btree_iter_set_pos(iter, next_pos);
 
-       return ret;
+       return 0;
 }
 
+/*
+ * Returns -EINTR if we had to drop locks:
+ */
 int bch2_fpunch_at(struct btree_trans *trans, struct btree_iter *iter,
-                  struct bpos end, u64 *journal_seq,
+                  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 ((k = bch2_btree_iter_peek(iter)).k &&
-              bkey_cmp(iter->pos, end) < 0) {
+       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)
-                       goto btree_err;
+                       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, &delete);
+               bch2_cut_back(end_pos, &delete);
 
-               ret = bch2_extent_update(trans, iter, &delete,
-                               &disk_res, journal_seq,
-                               0, i_sectors_delta);
+               ret = bch2_extent_update(trans, inum, iter, &delete,
+                               &disk_res, NULL,
+                               0, i_sectors_delta, false);
                bch2_disk_reservation_put(c, &disk_res);
-btree_err:
-               if (ret == -EINTR) {
-                       ret2 = ret;
-                       ret = 0;
-               }
-               if (ret)
-                       break;
-       }
-
-       if (bkey_cmp(iter->pos, end) > 0) {
-               bch2_btree_iter_set_pos(iter, end);
-               ret = bch2_btree_iter_traverse(iter);
        }
 
        return ret ?: ret2;
 }
 
-int bch2_fpunch(struct bch_fs *c, u64 inum, u64 start, u64 end,
-               u64 *journal_seq, s64 *i_sectors_delta)
+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 = 0;
+       struct btree_iter iter;
+       int ret;
 
        bch2_trans_init(&trans, c, BTREE_ITER_MAX, 1024);
-       iter = bch2_trans_get_iter(&trans, BTREE_ID_EXTENTS,
-                                  POS(inum, start),
-                                  BTREE_ITER_INTENT);
+       bch2_trans_iter_init(&trans, &iter, BTREE_ID_extents,
+                            POS(inum.inum, start),
+                            BTREE_ITER_INTENT);
 
-       ret = bch2_fpunch_at(&trans, iter, POS(inum, end),
-                            journal_seq, i_sectors_delta);
-       bch2_trans_exit(&trans);
+       ret = bch2_fpunch_at(&trans, &iter, inum, end, i_sectors_delta);
 
-       if (ret == -EINTR)
-               ret = 0;
+       bch2_trans_iter_exit(&trans, &iter);
+       bch2_trans_exit(&trans);
 
-       return ret;
+       return ret == -EINTR ? 0 : ret;
 }
 
 int bch2_write_index_default(struct bch_write_op *op)
 {
        struct bch_fs *c = op->c;
-       struct bkey_on_stack sk;
+       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;
+       struct btree_iter iter;
+       subvol_inum inum = {
+               .subvol = op->subvol,
+               .inum   = k->k.p.inode,
+       };
        int ret;
 
-       bkey_on_stack_init(&sk);
-       bch2_trans_init(&trans, c, BTREE_ITER_MAX, 1024);
+       BUG_ON(!inum.subvol);
 
-       iter = bch2_trans_get_iter(&trans, BTREE_ID_EXTENTS,
-                                  bkey_start_pos(&k->k),
-                                  BTREE_ITER_SLOTS|BTREE_ITER_INTENT);
+       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;
 
-               bkey_on_stack_realloc(&sk, c, k->k.u64s);
-               bkey_copy(sk.k, k);
-               bch2_cut_front(iter->pos, sk.k);
+               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, iter, sk.k,
+               ret = bch2_extent_update(&trans, inum, &iter, sk.k,
                                         &op->res, op_journal_seq(op),
-                                        op->new_i_size, &op->i_sectors_delta);
+                                        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 (bkey_cmp(iter->pos, k->k.p) >= 0)
-                       bch2_keylist_pop_front(keys);
+               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);
-       bkey_on_stack_exit(&sk, c);
+       bch2_bkey_buf_exit(&sk, c);
 
        return ret;
 }
@@ -479,9 +493,6 @@ void bch2_submit_wbio_replicas(struct bch_write_bio *wbio, struct bch_fs *c,
                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));
@@ -511,9 +522,6 @@ static void bch2_write_done(struct closure *cl)
 
        bch2_time_stats_update(&c->times[BCH_TIME_data_write], op->start_time);
 
-       if (!(op->flags & BCH_WRITE_FROM_INTERNAL))
-               up(&c->io_in_flight);
-
        if (op->end_io) {
                EBUG_ON(cl->parent);
                closure_debug_destroy(cl);
@@ -578,7 +586,8 @@ static void __bch2_write_index(struct bch_write_op *op)
                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;
                }
        }
@@ -623,7 +632,10 @@ 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: %s",
+       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);
 
@@ -653,11 +665,7 @@ static void init_append_extent(struct bch_write_op *op,
 {
        struct bch_fs *c = op->c;
        struct bkey_i_extent *e;
-       struct open_bucket *ob;
-       unsigned i;
 
-       BUG_ON(crc.compressed_size > wp->sectors_free);
-       wp->sectors_free -= crc.compressed_size;
        op->pos.offset += crc.uncompressed_size;
 
        e = bkey_extent_init(op->insert_keys.top);
@@ -670,22 +678,8 @@ static void init_append_extent(struct bch_write_op *op,
            crc.nonce)
                bch2_extent_crc_append(&e->k_i, crc);
 
-       open_bucket_for_each(c, &wp->ptrs, ob, i) {
-               struct bch_dev *ca = bch_dev_bkey_exists(c, ob->ptr.dev);
-               union bch_extent_entry *end =
-                       bkey_val_end(bkey_i_to_s(&e->k_i));
-
-               end->ptr = ob->ptr;
-               end->ptr.type = 1 << BCH_EXTENT_ENTRY_ptr;
-               end->ptr.cached = !ca->mi.durability ||
-                       (op->flags & BCH_WRITE_CACHED) != 0;
-               end->ptr.offset += ca->mi.bucket_size - ob->sectors_free;
-
-               e->k.u64s++;
-
-               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);
 }
@@ -705,6 +699,8 @@ static struct bio *bch2_write_bio_alloc(struct bch_fs *c,
                                       ? ((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);
        wbio->put_bio           = true;
@@ -724,7 +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 =
@@ -768,6 +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;
@@ -782,10 +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 {
@@ -870,7 +867,6 @@ static int bch2_write_extent(struct bch_write_op *op, struct write_point *wp,
        struct bio *src = &op->wbio.bio, *dst = src;
        struct bvec_iter saved_iter;
        void *ec_buf;
-       struct bpos ec_pos = op->pos;
        unsigned total_output = 0, total_input = 0;
        bool bounce = false;
        bool page_alloc_failed = false;
@@ -887,7 +883,6 @@ static int bch2_write_extent(struct bch_write_op *op, struct write_point *wp,
                ret = -EIO;
                goto err;
        case PREP_ENCODED_CHECKSUM_ERR:
-               BUG();
                goto csum_err;
        case PREP_ENCODED_DO_WRITE:
                /* XXX look for bug here */
@@ -923,8 +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 &&
@@ -944,7 +939,7 @@ static int bch2_write_extent(struct bch_write_op *op, struct write_point *wp,
 
                        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);
@@ -1002,8 +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;
@@ -1041,9 +1039,6 @@ 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... */
-       bch2_ec_add_backpointer(c, wp, ec_pos, total_input >> 9);
-
        *_dst = dst;
        return more;
 csum_err:
@@ -1064,7 +1059,7 @@ 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;
+       struct bio *bio = NULL;
        bool skip_put = true;
        unsigned nofs_flags;
        int ret;
@@ -1102,7 +1097,7 @@ again:
                 */
                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,
@@ -1280,26 +1275,20 @@ void bch2_write(struct closure *cl)
        bch2_keylist_init(&op->insert_keys, op->inline_keys);
        wbio_init(bio)->put_bio = false;
 
-       if (bio_sectors(bio) & (c->opts.block_size - 1)) {
-               __bcache_io_error(c, "misaligned write");
+       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)) {
-               if (!(op->flags & BCH_WRITE_FROM_INTERNAL))
-                       __bcache_io_error(c, "read only");
                op->error = -EROFS;
                goto err;
        }
 
-       /*
-        * Can't ratelimit copygc - we'd deadlock:
-        */
-       if (!(op->flags & BCH_WRITE_FROM_INTERNAL))
-               down(&c->io_in_flight);
-
+       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,
@@ -1414,7 +1403,7 @@ 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);
 }
 
@@ -1518,8 +1507,8 @@ static struct promote_op *promote_alloc(struct bch_fs *c,
 
        promote = __promote_alloc(c,
                                  k.k->type == KEY_TYPE_reflink_v
-                                 ? BTREE_ID_REFLINK
-                                 : BTREE_ID_EXTENTS,
+                                 ? BTREE_ID_reflink
+                                 : BTREE_ID_extents,
                                  k, pos, pick, opts, sectors, rbio);
        if (!promote)
                return NULL;
@@ -1599,134 +1588,63 @@ static void bch2_rbio_done(struct bch_read_bio *rbio)
 }
 
 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;
-       struct bkey_on_stack sk;
+       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;
 
-       bkey_on_stack_init(&sk);
+       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_on_stack_reassemble(&sk, c, k);
+       bch2_bkey_buf_reassemble(&sk, c, k);
        k = bkey_i_to_s_c(sk.k);
        bch2_trans_unlock(&trans);
 
        if (!bch2_bkey_matches_ptr(c, k,
                                   rbio->pick.ptr,
-                                  rbio->pos.offset -
+                                  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(&trans, rbio, bvec_iter, k, 0, 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);
-       bkey_on_stack_exit(&sk, c);
+       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_on_stack sk;
-       struct bkey_s_c k;
-       int ret;
-
-       flags &= ~BCH_READ_LAST_FRAGMENT;
-       flags |= BCH_READ_MUST_CLONE;
-
-       bkey_on_stack_init(&sk);
-       bch2_trans_init(&trans, c, 0, 0);
-retry:
-       bch2_trans_begin(&trans);
-
-       for_each_btree_key(&trans, iter, BTREE_ID_EXTENTS,
-                          POS(inode, bvec_iter.bi_sector),
-                          BTREE_ITER_SLOTS, k, ret) {
-               unsigned bytes, sectors, offset_into_extent;
-
-               bkey_on_stack_reassemble(&sk, c, k);
-
-               offset_into_extent = iter->pos.offset -
-                       bkey_start_offset(k.k);
-               sectors = k.k->size - offset_into_extent;
-
-               ret = bch2_read_indirect_extent(&trans,
-                                       &offset_into_extent, &sk);
-               if (ret)
-                       break;
-
-               k = bkey_i_to_s_c(sk.k);
-
-               sectors = min(sectors, k.k->size - offset_into_extent);
-
-               bch2_trans_unlock(&trans);
-
-               bytes = min(sectors, bvec_iter_sectors(bvec_iter)) << 9;
-               swap(bvec_iter.bi_size, bytes);
-
-               ret = __bch2_read_extent(&trans, rbio, bvec_iter, k,
-                               offset_into_extent, 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 (ret == -EINTR)
-               goto retry;
-       /*
-        * 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);
-       bkey_on_stack_exit(&sk, c);
-       bch2_rbio_done(rbio);
-}
-
 static void bch2_rbio_retry(struct work_struct *work)
 {
        struct bch_read_bio *rbio =
@@ -1734,7 +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);
@@ -1749,10 +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,
@@ -1778,9 +1703,9 @@ static int __bch2_rbio_narrow_crcs(struct btree_trans *trans,
                                   struct bch_read_bio *rbio)
 {
        struct bch_fs *c = rbio->c;
-       u64 data_offset = rbio->pos.offset - rbio->pick.crc.offset;
+       u64 data_offset = rbio->data_pos.offset - rbio->pick.crc.offset;
        struct bch_extent_crc_unpacked new_crc;
-       struct btree_iter *iter = NULL;
+       struct btree_iter iter;
        struct bkey_i *new;
        struct bkey_s_c k;
        int ret = 0;
@@ -1788,26 +1713,12 @@ static int __bch2_rbio_narrow_crcs(struct btree_trans *trans,
        if (crc_is_compressed(rbio->pick.crc))
                return 0;
 
-       iter = bch2_trans_get_iter(trans, BTREE_ID_EXTENTS, rbio->pos,
-                                  BTREE_ITER_SLOTS|BTREE_ITER_INTENT);
-       if ((ret = PTR_ERR_OR_ZERO(iter)))
-               goto out;
-
-       k = bch2_btree_iter_peek_slot(iter);
+       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;
 
-       /*
-        * going to be temporarily appending another checksum entry:
-        */
-       new = bch2_trans_kmalloc(trans, bkey_bytes(k.k) +
-                                BKEY_EXTENT_U64s_MAX * 8);
-       if ((ret = PTR_ERR_OR_ZERO(new)))
-               goto out;
-
-       bkey_reassemble(new, k);
-       k = bkey_i_to_s_c(new);
-
        if (bversion_cmp(k.k->version, rbio->version) ||
            !bch2_bkey_matches_ptr(c, k, rbio->pick.ptr, data_offset))
                goto out;
@@ -1826,12 +1737,23 @@ static int __bch2_rbio_narrow_crcs(struct btree_trans *trans,
                goto out;
        }
 
+       /*
+        * 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, iter, new, 0);
+       ret = bch2_trans_update(trans, &iter, new,
+                               BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
 out:
-       bch2_trans_iter_put(trans, iter);
+       bch2_trans_iter_exit(trans, &iter);
        return ret;
 }
 
@@ -1853,7 +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) {
@@ -1868,6 +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);
 
@@ -1879,7 +1812,10 @@ static void __bch2_read_endio(struct work_struct *work)
        crc.live_size   = bvec_iter_sectors(rbio->bvec_iter);
 
        if (crc_is_compressed(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;
+
                if (bch2_bio_uncompress(c, src, dst, dst_iter, crc))
                        goto decompression_err;
        } else {
@@ -1890,7 +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;
@@ -1903,7 +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;
        }
@@ -1912,6 +1853,8 @@ nodecode:
                rbio = bch2_rbio_free(rbio);
                bch2_rbio_done(rbio);
        }
+out:
+       memalloc_nofs_restore(nofs_flags);
        return;
 csum_err:
        /*
@@ -1922,22 +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)
@@ -1957,15 +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; %s",
+       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)
@@ -1987,9 +1935,9 @@ static void bch2_read_endio(struct bio *bio)
 
 int __bch2_read_indirect_extent(struct btree_trans *trans,
                                unsigned *offset_into_extent,
-                               struct bkey_on_stack *orig_k)
+                               struct bkey_buf *orig_k)
 {
-       struct btree_iter *iter;
+       struct btree_iter iter;
        struct bkey_s_c k;
        u64 reflink_offset;
        int ret;
@@ -1997,45 +1945,81 @@ int __bch2_read_indirect_extent(struct btree_trans *trans,
        reflink_offset = le64_to_cpu(bkey_i_to_reflink_p(orig_k->k)->v.idx) +
                *offset_into_extent;
 
-       iter = bch2_trans_get_iter(trans, BTREE_ID_REFLINK,
-                                  POS(0, reflink_offset),
-                                  BTREE_ITER_SLOTS);
-       ret = PTR_ERR_OR_ZERO(iter);
-       if (ret)
-               return ret;
-
-       k = bch2_btree_iter_peek_slot(iter);
+       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) {
-               __bcache_io_error(trans->c,
-                               "pointer to nonexistent indirect extent");
+               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);
-       bkey_on_stack_reassemble(orig_k, trans->c, k);
+       *offset_into_extent = iter.pos.offset - bkey_start_offset(k.k);
+       bch2_bkey_buf_reassemble(orig_k, trans->c, k);
 err:
-       bch2_trans_iter_put(trans, iter);
+       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 bkey_s_c k,
+                      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)) {
@@ -2049,7 +2033,7 @@ int __bch2_read_extent(struct btree_trans *trans, struct bch_read_bio *orig,
                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: */
@@ -2057,12 +2041,32 @@ int __bch2_read_extent(struct btree_trans *trans, 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) {
                /*
@@ -2089,7 +2093,7 @@ int __bch2_read_extent(struct btree_trans *trans, struct bch_read_bio *orig,
        EBUG_ON(offset_into_extent + bvec_iter_sectors(iter) > k.k->size);
 
        if (crc_is_compressed(pick.crc) ||
-           (pick.crc.csum_type != BCH_CSUM_NONE &&
+           (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)) ||
@@ -2110,7 +2114,7 @@ int __bch2_read_extent(struct btree_trans *trans, struct bch_read_bio *orig,
                         pick.crc.offset ||
                         offset_into_extent));
 
-               pos.offset += offset_into_extent;
+               data_pos.offset += offset_into_extent;
                pick.ptr.offset += pick.crc.offset +
                        offset_into_extent;
                offset_into_extent              = 0;
@@ -2182,7 +2186,10 @@ get_bio:
        /* 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);
@@ -2194,9 +2201,14 @@ get_bio:
        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);
 
-       if (pick.ptr.cached)
+       /*
+        * 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);
 
@@ -2207,7 +2219,8 @@ get_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;
                }
@@ -2247,6 +2260,9 @@ out:
                        ret = READ_RETRY;
                }
 
+               if (!ret)
+                       goto out_read_done;
+
                return ret;
        }
 
@@ -2273,53 +2289,63 @@ 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 bkey_on_stack sk;
+       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(rbio->_state);
        BUG_ON(flags & BCH_READ_NODECODE);
-       BUG_ON(flags & BCH_READ_IN_RETRY);
-
-       rbio->c = c;
-       rbio->start_time = local_clock();
 
-       bkey_on_stack_init(&sk);
+       bch2_bkey_buf_init(&sk);
        bch2_trans_init(&trans, c, 0, 0);
 retry:
        bch2_trans_begin(&trans);
+       iter = (struct btree_iter) { NULL };
 
-       iter = bch2_trans_get_iter(&trans, BTREE_ID_EXTENTS,
-                                  POS(inode, rbio->bio.bi_iter.bi_sector),
-                                  BTREE_ITER_SLOTS);
+       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;
+
+               /*
+                * 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(inode, rbio->bio.bi_iter.bi_sector));
+               bch2_btree_iter_set_pos(&iter,
+                               POS(inum.inum, bvec_iter.bi_sector));
 
-               k = bch2_btree_iter_peek_slot(iter);
+               k = bch2_btree_iter_peek_slot(&iter);
                ret = bkey_err(k);
                if (ret)
-                       goto err;
+                       break;
 
-               offset_into_extent = iter->pos.offset -
+               offset_into_extent = iter.pos.offset -
                        bkey_start_offset(k.k);
                sectors = k.k->size - offset_into_extent;
 
-               bkey_on_stack_reassemble(&sk, c, k);
+               bch2_bkey_buf_reassemble(&sk, c, k);
 
-               ret = bch2_read_indirect_extent(&trans,
+               ret = bch2_read_indirect_extent(&trans, &data_btree,
                                        &offset_into_extent, &sk);
                if (ret)
-                       goto err;
+                       break;
 
                k = bkey_i_to_s_c(sk.k);
 
@@ -2329,37 +2355,43 @@ retry:
                 */
                sectors = min(sectors, k.k->size - offset_into_extent);
 
-               /*
-                * Unlock the iterator while the btree node's lock is still in
-                * cache, before doing the IO:
-                */
-               bch2_trans_unlock(&trans);
-
-               bytes = min(sectors, bio_sectors(&rbio->bio)) << 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(&trans, rbio, k, offset_into_extent, 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)
                        break;
 
-               swap(rbio->bio.bi_iter.bi_size, bytes);
-               bio_advance(&rbio->bio, bytes);
+               swap(bvec_iter.bi_size, bytes);
+               bio_advance_iter(&rbio->bio, &bvec_iter, bytes);
+
+               ret = btree_trans_too_many_iters(&trans);
+               if (ret)
+                       break;
        }
-out:
-       bch2_trans_exit(&trans);
-       bkey_on_stack_exit(&sk, c);
-       return;
 err:
-       if (ret == -EINTR)
+       bch2_trans_iter_exit(&trans, &iter);
+
+       if (ret == -EINTR || ret == READ_RETRY || ret == READ_RETRY_AVOID)
                goto retry;
 
-       bcache_io_error(c, &rbio->bio, "btree IO error: %i", ret);
-       bch2_rbio_done(rbio);
-       goto out;
+       bch2_trans_exit(&trans);
+       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)
@@ -2383,8 +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;