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bcachefs: Ensure bch2_btree_node_get() calls relock() after unlock()

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Fix a bug where bch2_btree_node_get() might call bch2_trans_unlock() (in
fill) without calling bch2_trans_relock(); this is a bug when it's done
in the core btree code.

Also, twea bch2_btree_node_mem_alloc() to drop btree locks before doing
a blocking memory allocation.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2023-05-28 02:35:34 -04:00
parent 70d41c9e27
commit e1d29c5fa1
1 changed files with 19 additions and 12 deletions
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31
fs/bcachefs/btree_cache.c
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@ -587,9 +587,10 @@ struct btree *bch2_btree_node_mem_alloc(struct btree_trans *trans, bool pcpu_rea
goto got_node;
}
b = __btree_node_mem_alloc(c, __GFP_NOWARN);
b = __btree_node_mem_alloc(c, GFP_NOWAIT|__GFP_NOWARN);
if (!b) {
mutex_unlock(&bc->lock);
bch2_trans_unlock(trans);
b = __btree_node_mem_alloc(c, GFP_KERNEL);
if (!b)
goto err;
@ -618,8 +619,11 @@ struct btree *bch2_btree_node_mem_alloc(struct btree_trans *trans, bool pcpu_rea
mutex_unlock(&bc->lock);
if (btree_node_data_alloc(c, b, __GFP_NOWARN|GFP_KERNEL))
goto err;
if (btree_node_data_alloc(c, b, GFP_NOWAIT|__GFP_NOWARN)) {
bch2_trans_unlock(trans);
if (btree_node_data_alloc(c, b, GFP_KERNEL|__GFP_NOWARN))
goto err;
}
mutex_lock(&bc->lock);
bc->used++;
@ -812,6 +816,7 @@ static struct btree *__bch2_btree_node_get(struct btree_trans *trans, struct btr
struct btree_cache *bc = &c->btree_cache;
struct btree *b;
struct bset_tree *t;
bool need_relock = false;
int ret;
EBUG_ON(level >= BTREE_MAX_DEPTH);
@ -825,6 +830,7 @@ static struct btree *__bch2_btree_node_get(struct btree_trans *trans, struct btr
*/
b = bch2_btree_node_fill(trans, path, k, path->btree_id,
level, lock_type, true);
need_relock = true;
/* We raced and found the btree node in the cache */
if (!b)
@ -863,6 +869,7 @@ static struct btree *__bch2_btree_node_get(struct btree_trans *trans, struct btr
six_unlock_type(&b->c.lock, lock_type);
bch2_trans_unlock(trans);
need_relock = true;
bch2_btree_node_wait_on_read(b);
@ -870,19 +877,19 @@ static struct btree *__bch2_btree_node_get(struct btree_trans *trans, struct btr
* should_be_locked is not set on this path yet, so we need to
* relock it specifically:
*/
if (trans) {
int ret = bch2_trans_relock(trans) ?:
bch2_btree_path_relock_intent(trans, path);
if (ret) {
BUG_ON(!trans->restarted);
return ERR_PTR(ret);
}
}
if (!six_relock_type(&b->c.lock, lock_type, seq))
goto retry;
}
if (unlikely(need_relock)) {
int ret = bch2_trans_relock(trans) ?:
bch2_btree_path_relock_intent(trans, path);
if (ret) {
six_unlock_type(&b->c.lock, lock_type);
return ERR_PTR(ret);
}
}
prefetch(b->aux_data);
for_each_bset(b, t) {