[PATCH 004 of 6] md: Use ffz instead of find_first_set to convert multiplier to shift.

From: NeilBrown
Date: Thu Sep 28 2006 - 22:54:56 EST



From: Paul Clements <paul.clements@xxxxxxxxxxxx>

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@xxxxxxx>

### Diffstat output
./drivers/md/bitmap.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff .prev/drivers/md/bitmap.c ./drivers/md/bitmap.c
--- .prev/drivers/md/bitmap.c 2006-09-29 11:44:38.000000000 +1000
+++ ./drivers/md/bitmap.c 2006-09-29 11:49:40.000000000 +1000
@@ -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) /
-
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