diff options
| author | Kent Overstreet <kent.overstreet@linux.dev> | 2022-08-26 21:55:00 +0300 |
|---|---|---|
| committer | Kent Overstreet <kent.overstreet@linux.dev> | 2023-10-23 00:09:40 +0300 |
| commit | 546180874ade7225676bc0cd5ea4e2388e2374bc (patch) | |
| tree | 7e20a1ce5a97ca2b956f38b99ef01862bf55fead | |
| parent | 534a591e4cf98d036e478b93de4a95ff126fb018 (diff) | |
| download | linux-546180874ade7225676bc0cd5ea4e2388e2374bc.tar.xz | |
bcachefs: Mark write locks before taking lock
six locks are unfair: while a thread is blocked trying to take a write
lock, new read locks will fail. The new deadlock cycle detector makes
use of our existing lock tracing, so we need to tell it we're holding a
write lock before we take the lock for it to work correctly.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
| -rw-r--r-- | fs/bcachefs/btree_locking.h | 9 | ||||
| -rw-r--r-- | fs/bcachefs/btree_update_leaf.c | 11 |
2 files changed, 16 insertions, 4 deletions
diff --git a/fs/bcachefs/btree_locking.h b/fs/bcachefs/btree_locking.h index 1e4c81d8084b..ab3161c1b1f4 100644 --- a/fs/bcachefs/btree_locking.h +++ b/fs/bcachefs/btree_locking.h @@ -271,10 +271,15 @@ static inline void bch2_btree_node_lock_write(struct btree_trans *trans, EBUG_ON(path->l[b->c.level].lock_seq != b->c.lock.state.seq); EBUG_ON(!btree_node_intent_locked(path, b->c.level)); + /* + * six locks are unfair, and read locks block while a thread wants a + * write lock: thus, we need to tell the cycle detector we have a write + * lock _before_ taking the lock: + */ + mark_btree_node_locked_noreset(path, b->c.level, SIX_LOCK_write); + if (unlikely(!six_trylock_write(&b->c.lock))) __bch2_btree_node_lock_write(trans, b); - - mark_btree_node_locked_noreset(path, b->c.level, SIX_LOCK_write); } /* relock: */ diff --git a/fs/bcachefs/btree_update_leaf.c b/fs/bcachefs/btree_update_leaf.c index 732d09d45041..a8306b16956d 100644 --- a/fs/bcachefs/btree_update_leaf.c +++ b/fs/bcachefs/btree_update_leaf.c @@ -817,6 +817,13 @@ static inline int trans_lock_write(struct btree_trans *trans) if (same_leaf_as_prev(trans, i)) continue; + /* + * six locks are unfair, and read locks block while a thread + * wants a write lock: thus, we need to tell the cycle detector + * we have a write lock _before_ taking the lock: + */ + mark_btree_node_locked_noreset(i->path, i->level, SIX_LOCK_write); + if (!six_trylock_write(&insert_l(i)->b->c.lock)) { if (have_conflicting_read_lock(trans, i->path)) goto fail; @@ -828,13 +835,13 @@ static inline int trans_lock_write(struct btree_trans *trans) BUG_ON(ret); } - mark_btree_node_locked_noreset(i->path, i->level, SIX_LOCK_write); - bch2_btree_node_prep_for_write(trans, i->path, insert_l(i)->b); } return 0; fail: + mark_btree_node_locked_noreset(i->path, i->level, SIX_LOCK_intent); + while (--i >= trans->updates) { if (same_leaf_as_prev(trans, i)) continue; |