Commit 01db5e5f authored by Kent Overstreet's avatar Kent Overstreet
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bcachefs: Fix insufficient disk reservation with compression + snapshots 



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

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent b0c279ff

fs/bcachefs/btree_update.c

+8 −7
Original line number Diff line number Diff line
@@ -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;