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super-0.90: don't write bitmap larger than 60K 

The 4K superblock can be as close as 64K from the end
of the device.  As the bitmap (with header) lives after
the superblock (with 0.90 metadata) there could be as
little as 60K of space.
So limit the bitmaps to 59.5K, and only write 60K including
the header.

The bug fixed here means that bitmaps cannot be created
on devices which are exact multiples of 64K in size

Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown 2010-07-07 21:09:23 +10:00
parent 3d5279b053
commit 50526e9090
1 changed files with 2 additions and 2 deletions
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4
super0.c
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@ -962,7 +962,7 @@ static int add_internal_bitmap0(struct supertype *st, int *chunkp,
* size is in sectors, chunk is in bytes !!!
*/
unsigned long long bits;
unsigned long long max_bits = 60*1024*8;
unsigned long long max_bits = (60*1024 - sizeof(bitmap_super_t))*8;
unsigned long long min_chunk;
int chunk = *chunkp;
mdp_super_t *sb = st->sb;
@ -1048,7 +1048,7 @@ static int write_bitmap0(struct supertype *st, int fd)
memset(buf, 0xff, 4096);
memcpy(buf, ((char*)sb)+MD_SB_BYTES, sizeof(bitmap_super_t));
towrite = 64*1024;
towrite = 60*1024;
while (towrite > 0) {
n = towrite;
if (n > 4096)