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| 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/buckets.c | |
| parent | e76a2b65b0565f55ea668ec46d54f6a00b8ea9fc (diff) | |
| download | linux-68573b936d3fceda9cd5cce3a577e035d19ad426.tar.gz linux-68573b936d3fceda9cd5cce3a577e035d19ad426.tar.bz2 linux-68573b936d3fceda9cd5cce3a577e035d19ad426.zip | |
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/buckets.c')
| -rw-r--r-- | fs/bcachefs/buckets.c | 17 |
1 files changed, 8 insertions, 9 deletions
diff --git a/fs/bcachefs/buckets.c b/fs/bcachefs/buckets.c index 314ee3e0187f..5145066330ed 100644 --- a/fs/bcachefs/buckets.c +++ b/fs/bcachefs/buckets.c @@ -916,13 +916,13 @@ void bch2_trans_account_disk_usage_change(struct btree_trans *trans) */ s64 should_not_have_added = added - (s64) disk_res_sectors; if (unlikely(should_not_have_added > 0)) { - u64 old, new, v = atomic64_read(&c->sectors_available); + u64 old, new; + old = atomic64_read(&c->sectors_available); do { - old = v; new = max_t(s64, 0, old - should_not_have_added); - } while ((v = atomic64_cmpxchg(&c->sectors_available, - old, new)) != old); + } while (!atomic64_try_cmpxchg(&c->sectors_available, + &old, new)); added -= should_not_have_added; warn = true; @@ -1523,7 +1523,7 @@ int __bch2_disk_reservation_add(struct bch_fs *c, struct disk_reservation *res, u64 sectors, int flags) { struct bch_fs_pcpu *pcpu; - u64 old, v, get; + u64 old, get; s64 sectors_available; int ret; @@ -1534,17 +1534,16 @@ int __bch2_disk_reservation_add(struct bch_fs *c, struct disk_reservation *res, if (sectors <= pcpu->sectors_available) goto out; - v = atomic64_read(&c->sectors_available); + old = atomic64_read(&c->sectors_available); do { - old = v; get = min((u64) sectors + SECTORS_CACHE, old); if (get < sectors) { preempt_enable(); goto recalculate; } - } while ((v = atomic64_cmpxchg(&c->sectors_available, - old, old - get)) != old); + } while (!atomic64_try_cmpxchg(&c->sectors_available, + &old, old - get)); pcpu->sectors_available += get; |