md/bitmap: fix calculation of 'chunks' - missing shift. (b16b1b6c) · Commits · 戴 / test

commit "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>

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

		/*

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