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bcachefs: Fix split_race livelock

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bch2_btree_update_start() calculates which nodes are going to have to be
split/rewritten, so that we know how many nodes to reserve and how deep
in the tree we have to take locks.

But btree node merges require inserting two keys into the parent node,
not just splits.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2023-11-26 18:31:11 -05:00
parent 03013bb0c6
commit 5510a4af52
1 changed files with 5 additions and 1 deletions
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6
fs/bcachefs/btree_update_interior.c
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@ -1071,8 +1071,12 @@ bch2_btree_update_start(struct btree_trans *trans, struct btree_path *path,
break;
}
/*
* Always check for space for two keys, even if we won't have to
* split at prior level - it might have been a merge instead:
*/
if (bch2_btree_node_insert_fits(c, path->l[update_level].b,
BKEY_BTREE_PTR_U64s_MAX * (1 + split)))
BKEY_BTREE_PTR_U64s_MAX * 2))
break;
split = path->l[update_level].b->nr.live_u64s > BTREE_SPLIT_THRESHOLD(c);