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 --- fs/ext2/balloc.c | 4 ++-- fs/ext3/balloc.c | 2 +- fs/ext4/balloc.c | 2 +- include/linux/percpu_counter.h | 5 +++++ 4 files changed, 9 insertions(+), 4 deletions(-) Index: linux-2.6/fs/ext2/balloc.c =================================================================== --- linux-2.6.orig/fs/ext2/balloc.c +++ linux-2.6/fs/ext2/balloc.c @@ -163,7 +163,7 @@ static int reserve_blocks(struct super_b return 0; } - percpu_counter_add(&sbi->s_freeblocks_counter, -count); + percpu_counter_sub(&sbi->s_freeblocks_counter, count); sb->s_dirt = 1; return count; } @@ -1402,7 +1402,7 @@ allocated: } group_adjust_blocks(sb, group_no, gdp, gdp_bh, -num); - percpu_counter_add(&sbi->s_freeblocks_counter, -num); + percpu_counter_sub(&sbi->s_freeblocks_counter, num); mark_buffer_dirty(bitmap_bh); if (sb->s_flags & MS_SYNCHRONOUS) Index: linux-2.6/fs/ext3/balloc.c =================================================================== --- linux-2.6.orig/fs/ext3/balloc.c +++ linux-2.6/fs/ext3/balloc.c @@ -1672,7 +1672,7 @@ 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); Index: linux-2.6/fs/ext4/balloc.c =================================================================== --- linux-2.6.orig/fs/ext4/balloc.c +++ linux-2.6/fs/ext4/balloc.c @@ -1697,7 +1697,7 @@ 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); Index: linux-2.6/include/linux/percpu_counter.h =================================================================== --- linux-2.6.orig/include/linux/percpu_counter.h +++ linux-2.6/include/linux/percpu_counter.h @@ -105,4 +105,9 @@ static inline void percpu_counter_dec(st 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 */ -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/