md/raid1: avoid overflow in raid1 resync when bitmap is in use.
bitmap_start_sync returns - via a pass-by-reference variable - the
number of sectors before we need to check with the bitmap again.
Since commit ef4256733506f245 this number can be substantially larger,
2^27 is a common value.
Unfortunately it is an 'int' and so when raid1.c:sync_request shifts
it 9 places to the left it becomes 0. This results in a zero-length
read which the scsi layer justifiably complains about.
This patch just removes the shift so the common case becomes safe with
a trivially-correct patch.
In the next merge window we will convert this 'int' to a 'sector_t'
Reported-by: "George Spelvin" <linux@horizon.com>
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index ad83a4d..fba4d2f 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1912,7 +1912,7 @@
!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
break;
BUG_ON(sync_blocks < (PAGE_SIZE>>9));
- if (len > (sync_blocks<<9))
+ if ((len >> 9) > sync_blocks)
len = sync_blocks<<9;
}