diff options
| author | Uros Bizjak <ubizjak@gmail.com> | 2024-05-23 11:19:26 +0200 |
|---|---|---|
| committer | Kent Overstreet <kent.overstreet@linux.dev> | 2024-07-14 19:00:12 -0400 |
| commit | 68573b936d3fceda9cd5cce3a577e035d19ad426 (patch) | |
| tree | 872f291bf9b8d6f439c9d0a5bd372d42557e8e6b /fs/bcachefs/btree_trans_commit.c | |
| parent | e76a2b65b0565f55ea668ec46d54f6a00b8ea9fc (diff) | |
bcachefs: Use try_cmpxchg() family of functions instead of cmpxchg()
Use try_cmpxchg() family of functions instead of
cmpxchg (*ptr, old, new) == old. x86 CMPXCHG instruction returns
success in ZF flag, so this change saves a compare after cmpxchg
(and related move instruction in front of cmpxchg).
Also, try_cmpxchg() implicitly assigns old *ptr value to "old" when
cmpxchg fails. There is no need to re-read the value in the loop.
No functional change intended.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Brian Foster <bfoster@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Diffstat (limited to 'fs/bcachefs/btree_trans_commit.c')
| -rw-r--r-- | fs/bcachefs/btree_trans_commit.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/fs/bcachefs/btree_trans_commit.c b/fs/bcachefs/btree_trans_commit.c index 74e1ff225674..5e67dcb30f33 100644 --- a/fs/bcachefs/btree_trans_commit.c +++ b/fs/bcachefs/btree_trans_commit.c @@ -228,14 +228,14 @@ static int __btree_node_flush(struct journal *j, struct journal_entry_pin *pin, struct btree_write *w = container_of(pin, struct btree_write, journal); struct btree *b = container_of(w, struct btree, writes[i]); struct btree_trans *trans = bch2_trans_get(c); - unsigned long old, new, v; + unsigned long old, new; unsigned idx = w - b->writes; btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_read); - v = READ_ONCE(b->flags); + old = READ_ONCE(b->flags); do { - old = new = v; + new = old; if (!(old & (1 << BTREE_NODE_dirty)) || !!(old & (1 << BTREE_NODE_write_idx)) != idx || @@ -245,7 +245,7 @@ static int __btree_node_flush(struct journal *j, struct journal_entry_pin *pin, new &= ~BTREE_WRITE_TYPE_MASK; new |= BTREE_WRITE_journal_reclaim; new |= 1 << BTREE_NODE_need_write; - } while ((v = cmpxchg(&b->flags, old, new)) != old); + } while (!try_cmpxchg(&b->flags, &old, new)); btree_node_write_if_need(c, b, SIX_LOCK_read); six_unlock_read(&b->c.lock); |