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Commit b16b1b6c authored by NeilBrown's avatar NeilBrown
Browse files

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: default avatarKarl Newman <siliconfiend@gmail.com>
Tested-by: default avatarKarl Newman <siliconfiend@gmail.com>
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent 69964ea4

drivers/md/bitmap.c

+1 −2
Original line number Diff line number Diff line
@@ -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;

drivers/md/bitmap.h

+0 −3
Original line number Diff line number Diff line
@@ -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



/*