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author | Kent Overstreet <kent.overstreet@linux.dev> | 2023-11-24 21:51:45 -0500 |
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committer | Kent Overstreet <kent.overstreet@linux.dev> | 2023-11-25 21:48:42 -0500 |
commit | 7d9f8468ff7589073981b3eb8b175945c7dcd13c (patch) | |
tree | 476fc1bf41080fb88acfc5203974ddd91ee7b1af /fs/bcachefs/data_update.c | |
parent | 0af8a06a4ce823e380385cdd9538cdd968a1ffae (diff) | |
download | linux-7d9f8468ff7589073981b3eb8b175945c7dcd13c.tar.gz linux-7d9f8468ff7589073981b3eb8b175945c7dcd13c.tar.bz2 linux-7d9f8468ff7589073981b3eb8b175945c7dcd13c.zip |
bcachefs: Data update path won't accidentaly grow replicas
Previously, there was a bug where if an extent had greater durability
than required (because we needed to move a durability=1 pointer and
ended up putting it on a durability 2 device), we would submit a write
for replicas=2 - the durability of the pointer being rewritten - instead
of the number of replicas required to bring it back up to the
data_replicas option.
This, plus the allocation path sometimes allocating on a greater
durability device than requested, meant that extents could continue
having more and more replicas added as they were being rewritten.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Diffstat (limited to 'fs/bcachefs/data_update.c')
-rw-r--r-- | fs/bcachefs/data_update.c | 92 |
1 files changed, 82 insertions, 10 deletions
diff --git a/fs/bcachefs/data_update.c b/fs/bcachefs/data_update.c index 5ed66202c226..71aa5e59787b 100644 --- a/fs/bcachefs/data_update.c +++ b/fs/bcachefs/data_update.c @@ -356,7 +356,7 @@ void bch2_data_update_exit(struct data_update *update) bch2_bio_free_pages_pool(c, &update->op.wbio.bio); } -void bch2_update_unwritten_extent(struct btree_trans *trans, +static void bch2_update_unwritten_extent(struct btree_trans *trans, struct data_update *update) { struct bch_fs *c = update->op.c; @@ -436,7 +436,51 @@ void bch2_update_unwritten_extent(struct btree_trans *trans, } } +int bch2_extent_drop_ptrs(struct btree_trans *trans, + struct btree_iter *iter, + struct bkey_s_c k, + struct data_update_opts data_opts) +{ + struct bch_fs *c = trans->c; + struct bkey_i *n; + int ret; + + n = bch2_bkey_make_mut_noupdate(trans, k); + ret = PTR_ERR_OR_ZERO(n); + if (ret) + return ret; + + while (data_opts.kill_ptrs) { + unsigned i = 0, drop = __fls(data_opts.kill_ptrs); + struct bch_extent_ptr *ptr; + + bch2_bkey_drop_ptrs(bkey_i_to_s(n), ptr, i++ == drop); + data_opts.kill_ptrs ^= 1U << drop; + } + + /* + * If the new extent no longer has any pointers, bch2_extent_normalize() + * will do the appropriate thing with it (turning it into a + * KEY_TYPE_error key, or just a discard if it was a cached extent) + */ + bch2_extent_normalize(c, bkey_i_to_s(n)); + + /* + * Since we're not inserting through an extent iterator + * (BTREE_ITER_ALL_SNAPSHOTS iterators aren't extent iterators), + * we aren't using the extent overwrite path to delete, we're + * just using the normal key deletion path: + */ + if (bkey_deleted(&n->k)) + n->k.size = 0; + + return bch2_trans_relock(trans) ?: + bch2_trans_update(trans, iter, n, BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) ?: + bch2_trans_commit(trans, NULL, NULL, BTREE_INSERT_NOFAIL); +} + int bch2_data_update_init(struct btree_trans *trans, + struct btree_iter *iter, struct moving_context *ctxt, struct data_update *m, struct write_point_specifier wp, @@ -452,7 +496,7 @@ int bch2_data_update_init(struct btree_trans *trans, const struct bch_extent_ptr *ptr; unsigned i, reserve_sectors = k.k->size * data_opts.extra_replicas; unsigned ptrs_locked = 0; - int ret; + int ret = 0; bch2_bkey_buf_init(&m->k); bch2_bkey_buf_reassemble(&m->k, c, k); @@ -478,6 +522,8 @@ int bch2_data_update_init(struct btree_trans *trans, bkey_for_each_ptr(ptrs, ptr) percpu_ref_get(&bch_dev_bkey_exists(c, ptr->dev)->ref); + unsigned durability_have = 0, durability_removing = 0; + i = 0; bkey_for_each_ptr_decode(k.k, ptrs, p, entry) { bool locked; @@ -489,8 +535,11 @@ int bch2_data_update_init(struct btree_trans *trans, reserve_sectors += k.k->size; m->op.nr_replicas += bch2_extent_ptr_desired_durability(c, &p); - } else if (!p.ptr.cached) { + durability_removing += bch2_extent_ptr_desired_durability(c, &p); + } else if (!p.ptr.cached && + !((1U << i) & m->data_opts.kill_ptrs)) { bch2_dev_list_add_dev(&m->op.devs_have, p.ptr.dev); + durability_have += bch2_extent_ptr_durability(c, &p); } /* @@ -529,6 +578,29 @@ int bch2_data_update_init(struct btree_trans *trans, i++; } + /* + * If current extent durability is less than io_opts.data_replicas, + * we're not trying to rereplicate the extent up to data_replicas here - + * unless extra_replicas was specified + * + * Increasing replication is an explicit operation triggered by + * rereplicate, currently, so that users don't get an unexpected -ENOSPC + */ + if (durability_have >= io_opts.data_replicas) { + m->data_opts.kill_ptrs |= m->data_opts.rewrite_ptrs; + m->data_opts.rewrite_ptrs = 0; + /* if iter == NULL, it's just a promote */ + if (iter) + ret = bch2_extent_drop_ptrs(trans, iter, k, data_opts); + goto done; + } + + m->op.nr_replicas = min(durability_removing, io_opts.data_replicas - durability_have) + + m->data_opts.extra_replicas; + m->op.nr_replicas_required = m->op.nr_replicas; + + BUG_ON(!m->op.nr_replicas); + if (reserve_sectors) { ret = bch2_disk_reservation_add(c, &m->op.res, reserve_sectors, m->data_opts.extra_replicas @@ -538,14 +610,11 @@ int bch2_data_update_init(struct btree_trans *trans, goto err; } - m->op.nr_replicas += m->data_opts.extra_replicas; - m->op.nr_replicas_required = m->op.nr_replicas; - - BUG_ON(!m->op.nr_replicas); + if (bkey_extent_is_unwritten(k)) { + bch2_update_unwritten_extent(trans, m); + goto done; + } - /* Special handling required: */ - if (bkey_extent_is_unwritten(k)) - return -BCH_ERR_unwritten_extent_update; return 0; err: i = 0; @@ -560,6 +629,9 @@ err: bch2_bkey_buf_exit(&m->k, c); bch2_bio_free_pages_pool(c, &m->op.wbio.bio); return ret; +done: + bch2_data_update_exit(m); + return ret ?: -BCH_ERR_data_update_done; } void bch2_data_update_opts_normalize(struct bkey_s_c k, struct data_update_opts *opts) |