Re: [BISECT] Kernel panic, RIP bitmap_create

[NeilBrown <neilb@suse.de>]

[-- Attachment #1: Type: text/plain, Size: 1245 bytes --]


I've managed to find a bug, but it is fairly minor and I cannot see how
it would cause a crash.

The calculation of bitmap->chunks is wrong and will usually be 1 too small.

Does it make a difference for you?  I tend to doubt it.

Thanks,
NeilBrown


diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 97e73e5..17e2b47 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 55ca5ae..b44b0aba 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
 
 /*

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 828 bytes --]