From 3cb4f9fa0c5f3ded9f70f85b70ee6d429834f911 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra <a.p.zijlstra@chello.nl> Date: Tue, 16 Oct 2007 23:25:42 -0700 Subject: 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> --- fs/ext4/balloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/ext4') 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); -- cgit v1.2.2