diff options
| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2007-10-16 23:25:42 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-10-17 08:42:44 -0700 |
| commit | 3cb4f9fa0c5f3ded9f70f85b70ee6d429834f911 (patch) | |
| tree | d1f45445fa98bd41a2f8986781f7c62b470a6b8d | |
| parent | aa0dff2d09bfa50b7d02714a45920c64568e699d (diff) | |
| download | lwn-3cb4f9fa0c5f3ded9f70f85b70ee6d429834f911.tar.gz lwn-3cb4f9fa0c5f3ded9f70f85b70ee6d429834f911.zip | |
lib: percpu_counter_sub
Hugh spotted that some code does:
percpu_counter_add(&counter, -unsignedlong)
which, when the amount argument is of type s32, sort-of works thanks to
two's-complement. However when we'd change the type to s64 this breaks on 32bit
machines, because the promotion rules zero extend the unsigned number.
Provide percpu_counter_sub() to hide the s64 cast. That is:
percpu_counter_sub(&counter, foo)
is equal to:
percpu_counter_add(&counter, -(s64)foo);
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/ext2/balloc.c | 2 | ||||
| -rw-r--r-- | fs/ext3/balloc.c | 2 | ||||
| -rw-r--r-- | fs/ext4/balloc.c | 2 | ||||
| -rw-r--r-- | include/linux/percpu_counter.h | 5 |
4 files changed, 8 insertions, 3 deletions
diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c index 53be25158560..9157fcf887bc 100644 --- a/fs/ext2/balloc.c +++ b/fs/ext2/balloc.c @@ -124,7 +124,7 @@ static int reserve_blocks(struct super_block *sb, int count) return 0; } - percpu_counter_add(&sbi->s_freeblocks_counter, -count); + percpu_counter_sub(&sbi->s_freeblocks_counter, count); sb->s_dirt = 1; return count; } diff --git a/fs/ext3/balloc.c b/fs/ext3/balloc.c index df575673e02d..d3758ee9cb5b 100644 --- a/fs/ext3/balloc.c +++ b/fs/ext3/balloc.c @@ -1633,7 +1633,7 @@ allocated: gdp->bg_free_blocks_count = cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count)-num); spin_unlock(sb_bgl_lock(sbi, group_no)); - percpu_counter_add(&sbi->s_freeblocks_counter, -num); + percpu_counter_sub(&sbi->s_freeblocks_counter, num); BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor"); err = ext3_journal_dirty_metadata(handle, gdp_bh); diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c index a141456cd491..8d59eec2e82b 100644 --- a/fs/ext4/balloc.c +++ b/fs/ext4/balloc.c @@ -1647,7 +1647,7 @@ allocated: gdp->bg_free_blocks_count = cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count)-num); spin_unlock(sb_bgl_lock(sbi, group_no)); - percpu_counter_add(&sbi->s_freeblocks_counter, -num); + percpu_counter_sub(&sbi->s_freeblocks_counter, num); BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor"); err = ext4_journal_dirty_metadata(handle, gdp_bh); diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h index b84fc8667de8..438a170187ec 100644 --- a/include/linux/percpu_counter.h +++ b/include/linux/percpu_counter.h @@ -105,4 +105,9 @@ static inline void percpu_counter_dec(struct percpu_counter *fbc) percpu_counter_add(fbc, -1); } +static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount) +{ + percpu_counter_add(fbc, -amount); +} + #endif /* _LINUX_PERCPU_COUNTER_H */ |