[dm-devel] [PATCH] dm: don't overallocate the tags space

[Mikulas Patocka]

bio_sectors returns the value in the units of 512-byte sectors (no matter
what's the real sector size of the device). dm-crypt multiplies
bio_sectors by on_disk_tag_size to calculate the space allocated for
integrity tags. If dm-crypt is running with sector size larger than 512,
it allocates more data than what's needed.

Device mapper trimmed this extra space when passing the bio to
dm-integrity, so this bug didn't result in any visible misbehavior. This
bug showed up when device mapper stopped trimming the bio.

Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>
Reported-by: Milan Broz <mbroz at redhat.com>

---
 drivers/md/dm-crypt.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6/drivers/md/dm-crypt.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-crypt.c	2019-02-08 14:12:19.000000000 +0100
+++ linux-2.6/drivers/md/dm-crypt.c	2019-02-08 14:12:19.000000000 +0100
@@ -932,7 +932,7 @@ static int dm_crypt_integrity_io_alloc(s
 	if (IS_ERR(bip))
 		return PTR_ERR(bip);
 
-	tag_len = io->cc->on_disk_tag_size * bio_sectors(bio);
+	tag_len = io->cc->on_disk_tag_size * (bio_sectors(bio) >> io->cc->sector_shift);
 
 	bip->bip_iter.bi_size = tag_len;
 	bip->bip_iter.bi_sector = io->cc->start + io->sector;