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bcachefs: Don't use bch2_btree_node_lock_write_nofail() in btree split path 

It turns out - btree splits happen with the rest of the transaction
still locked, to avoid unnecessary restarts, which means using nofail
doesn't work here - we can deadlock.

Fortunately, we now have the ability to return errors here.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2024-04-11 01:01:11 -04:00
parent 1189bdda6c
commit 2b3e79fea6
1 changed files with 26 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
fs/bcachefs/btree_update_interior.c
View File

@ -1280,23 +1280,29 @@ static void bch2_btree_set_root_inmem(struct bch_fs *c, struct btree *b)
bch2_recalc_btree_reserve(c);
}
static void bch2_btree_set_root(struct btree_update *as,
struct btree_trans *trans,
struct btree_path *path,
struct btree *b)
static int bch2_btree_set_root(struct btree_update *as,
struct btree_trans *trans,
struct btree_path *path,
struct btree *b,
bool nofail)
{
struct bch_fs *c = as->c;
struct btree *old;
trace_and_count(c, btree_node_set_root, trans, b);
old = btree_node_root(c, b);
struct btree *old = btree_node_root(c, b);
/*
* Ensure no one is using the old root while we switch to the
* new root:
*/
bch2_btree_node_lock_write_nofail(trans, path, &old->c);
if (nofail) {
bch2_btree_node_lock_write_nofail(trans, path, &old->c);
} else {
int ret = bch2_btree_node_lock_write(trans, path, &old->c);
if (ret)
return ret;
}
bch2_btree_set_root_inmem(c, b);
@ -1310,6 +1316,7 @@ static void bch2_btree_set_root(struct btree_update *as,
* depend on the new root would have to update the new root.
*/
bch2_btree_node_unlock_write(trans, path, old);
return 0;
}
/* Interior node updates: */
@ -1652,15 +1659,16 @@ static int btree_split(struct btree_update *as, struct btree_trans *trans,
if (parent) {
/* Split a non root node */
ret = bch2_btree_insert_node(as, trans, path, parent, &as->parent_keys);
if (ret)
goto err;
} else if (n3) {
bch2_btree_set_root(as, trans, trans->paths + path, n3);
ret = bch2_btree_set_root(as, trans, trans->paths + path, n3, false);
} else {
/* Root filled up but didn't need to be split */
bch2_btree_set_root(as, trans, trans->paths + path, n1);
ret = bch2_btree_set_root(as, trans, trans->paths + path, n1, false);
}
if (ret)
goto err;
if (n3) {
bch2_btree_update_get_open_buckets(as, n3);
bch2_btree_node_write(c, n3, SIX_LOCK_intent, 0);
@ -1863,7 +1871,9 @@ static void __btree_increase_depth(struct btree_update *as, struct btree_trans *
bch2_keylist_add(&as->parent_keys, &b->key);
btree_split_insert_keys(as, trans, path_idx, n, &as->parent_keys);
bch2_btree_set_root(as, trans, path, n);
int ret = bch2_btree_set_root(as, trans, path, n, true);
BUG_ON(ret);
bch2_btree_update_get_open_buckets(as, n);
bch2_btree_node_write(c, n, SIX_LOCK_intent, 0);
bch2_trans_node_add(trans, path, n);
@ -2106,12 +2116,13 @@ int bch2_btree_node_rewrite(struct btree_trans *trans,
if (parent) {
bch2_keylist_add(&as->parent_keys, &n->key);
ret = bch2_btree_insert_node(as, trans, iter->path, parent, &as->parent_keys);
if (ret)
goto err;
} else {
bch2_btree_set_root(as, trans, btree_iter_path(trans, iter), n);
ret = bch2_btree_set_root(as, trans, btree_iter_path(trans, iter), n, false);
}
if (ret)
goto err;
bch2_btree_update_get_open_buckets(as, n);
bch2_btree_node_write(c, n, SIX_LOCK_intent, 0);