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authorPeter Zijlstra2007-10-16 23:25:42 -0700
committerLinus Torvalds2007-10-17 08:42:44 -0700
commit3cb4f9fa0c5f3ded9f70f85b70ee6d429834f911 (patch)
treed1f45445fa98bd41a2f8986781f7c62b470a6b8d /fs/ext4
parentaa0dff2d09bfa50b7d02714a45920c64568e699d (diff)
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>
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/balloc.c2
1 files changed, 1 insertions, 1 deletions
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);