bio-integrity: Fix bio_integrity_verify segment start bug

This patch addresses a bug in bio_integrity_verify() code that has
been causing DIF READ verify operations to be silently skipped.

The issue is that bio->bi_idx will have been incremented within
bio_advance() code in the normal blk_update_request() ->
req_bio_endio() completion path, and bio_integrity_verify() is
using bio_for_each_segment() which starts the bio segment walk
at the current bio->bi_idx.

So instead use bio_for_each_segment_all() to always start the bio
segment walk from zero, regardless of the current bio->bi_idx
value after bio_advance() has been called.

Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Cc: stable@kernel.dk # >= v3.10
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 8 insertions, 7 deletions

diff --git a/fs/bio-integrity.c b/fs/bio-integrity.c
index 80d972d739e5..0bad24ddc2e7 100644
--- a/fs/bio-integrity.c
+++ b/fs/bio-integrity.c
@@ -447,20 +447,21 @@ static int bio_integrity_verify(struct bio *bio)
 {
         struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
         struct blk_integrity_exchg bix;
-        struct bio_vec bv;
-        struct bvec_iter iter;
+        struct bio_vec *bv;
         sector_t sector = bio->bi_integrity->bip_iter.bi_sector;
         unsigned int sectors, total, ret;
         void *prot_buf = bio->bi_integrity->bip_buf;
+        int i;
 
         ret = total = 0;
         bix.disk_name = bio->bi_bdev->bd_disk->disk_name;
         bix.sector_size = bi->sector_size;
 
-        bio_for_each_segment(bv, bio, iter) {
-                void *kaddr = kmap_atomic(bv.bv_page);
-                bix.data_buf = kaddr + bv.bv_offset;
-                bix.data_size = bv.bv_len;
+        bio_for_each_segment_all(bv, bio, i) {
+                void *kaddr = kmap_atomic(bv->bv_page);
+
+                bix.data_buf = kaddr + bv->bv_offset;
+                bix.data_size = bv->bv_len;
                 bix.prot_buf = prot_buf;
                 bix.sector = sector;
 
@@ -471,7 +472,7 @@ static int bio_integrity_verify(struct bio *bio)
                         return ret;
                 }
 
-                sectors = bv.bv_len / bi->sector_size;
+                sectors = bv->bv_len / bi->sector_size;
                 sector += sectors;
                 prot_buf += sectors * bi->tuple_size;
                 total += sectors * bi->tuple_size;