[PATCH] md: use ffz instead of find_first_set to convert multiplier to shift

find_first_set doesn't find the least-significant bit on bigendian machines,
so it is really wrong to use it.

ffs is closer, but takes an 'int' and we have a 'unsigned long'.  So use
ffz(~X) to convert a chunksize into a chunkshift.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 0a44298..8e67634 100644 (file)
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -1444,8 +1444,7 @@ int bitmap_create(mddev_t *mddev)
        if (err)
                goto error;
 
-       bitmap->chunkshift = find_first_bit(&bitmap->chunksize,
-                                       sizeof(bitmap->chunksize));
+       bitmap->chunkshift = ffz(~bitmap->chunksize);
 
        /* now that chunksize and chunkshift are set, we can use these macros */
        chunks = (blocks + CHUNK_BLOCK_RATIO(bitmap) - 1) /