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bcachefs: Fix insufficient disk reservation with compression + snapshots

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When overwriting and splitting existing extents, we weren't correctly
accounting for a 3 way split of a compressed extent.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2023-12-21 21:05:07 -05:00
parent b0c279ff6c
commit 01db5e5f2f
1 changed files with 8 additions and 7 deletions
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15
fs/bcachefs/btree_update.c
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@ -186,8 +186,11 @@ int bch2_trans_update_extent_overwrite(struct btree_trans *trans,
enum btree_id btree_id = iter->btree_id;
struct bkey_i *update;
struct bpos new_start = bkey_start_pos(new.k);
bool front_split = bkey_lt(bkey_start_pos(old.k), new_start);
bool back_split = bkey_gt(old.k->p, new.k->p);
unsigned front_split = bkey_lt(bkey_start_pos(old.k), new_start);
unsigned back_split = bkey_gt(old.k->p, new.k->p);
unsigned middle_split = (front_split || back_split) &&
old.k->p.snapshot != new.k->p.snapshot;
unsigned nr_splits = front_split + back_split + middle_split;
int ret = 0, compressed_sectors;
/*
@ -195,10 +198,9 @@ int bch2_trans_update_extent_overwrite(struct btree_trans *trans,
* so that __bch2_trans_commit() can increase our disk
* reservation:
*/
if (((front_split && back_split) ||
((front_split || back_split) && old.k->p.snapshot != new.k->p.snapshot)) &&
if (nr_splits > 1 &&
(compressed_sectors = bch2_bkey_sectors_compressed(old)))
trans->extra_journal_res += compressed_sectors;
trans->extra_journal_res += compressed_sectors * (nr_splits - 1);
if (front_split) {
update = bch2_bkey_make_mut_noupdate(trans, old);
@ -216,8 +218,7 @@ int bch2_trans_update_extent_overwrite(struct btree_trans *trans,
}
/* If we're overwriting in a different snapshot - middle split: */
if (old.k->p.snapshot != new.k->p.snapshot &&
(front_split || back_split)) {
if (middle_split) {
update = bch2_bkey_make_mut_noupdate(trans, old);
if ((ret = PTR_ERR_OR_ZERO(update)))
return ret;