From: Peter Zijlstra Date: Wed, 17 Oct 2007 06:25:42 +0000 (-0700) Subject: lib: percpu_counter_sub X-Git-Tag: v3.12-rc1~25827 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=3cb4f9fa0c5f3ded9f70f85b70ee6d429834f911;p=kernel%2Fkernel-generic.git 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 Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c index 53be251..9157fcf 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 df57567..d3758ee 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 a141456..8d59eec 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 b84fc86..438a170 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 */