md/bitmap: fix calculation of 'chunks' - missing shift.

commit 61a0d80c "md/bitmap: discard CHUNK_BLOCK_SHIFT macro"
replaced CHUNK_BLOCK_RATIO() by the same text that was
replacing CHUNK_BLOCK_SHIFT() - which is clearly wrong.

The result is that 'chunks' is often too small by 1,
which can sometimes result in a crash (not sure how).

So use the correct replacement, and get rid of CHUNK_BLOCK_RATIO
which is no longe used.

Reported-by: Karl Newman <siliconfiend@gmail.com>
Tested-by: Karl Newman <siliconfiend@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>

2 files changed, 1 insertions, 5 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 97e73e555d11..17e2b472e16d 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -1727,8 +1727,7 @@ int bitmap_create(struct mddev *mddev)
         bitmap->chunkshift = (ffz(~mddev->bitmap_info.chunksize)
                               - BITMAP_BLOCK_SHIFT);
 
-        /* now that chunksize and chunkshift are set, we can use these macros */
-        chunks = (blocks + bitmap->chunkshift - 1) >>
+        chunks = (blocks + (1 << bitmap->chunkshift) - 1) >>
                         bitmap->chunkshift;
         pages = (chunks + PAGE_COUNTER_RATIO - 1) / PAGE_COUNTER_RATIO;
 
diff --git a/drivers/md/bitmap.h b/drivers/md/bitmap.h
index 55ca5aec84e4..b44b0aba2d47 100644
--- a/drivers/md/bitmap.h
+++ b/drivers/md/bitmap.h
@@ -101,9 +101,6 @@ typedef __u16 bitmap_counter_t;
 
 #define BITMAP_BLOCK_SHIFT 9
 
-/* how many blocks per chunk? (this is variable) */
-#define CHUNK_BLOCK_RATIO(bitmap) ((bitmap)->mddev->bitmap_info.chunksize >> BITMAP_BLOCK_SHIFT)
-
 #endif
 
 /*