dm: fix clone_bio() to trigger blk_recount_segments() [Linux 5.0]

dm: fix clone_bio() to trigger blk_recount_segments() [Linux 5.0]

This Linux kernel change "dm: fix clone_bio() to trigger blk_recount_segments()" is included in the Linux 5.0 release. This change is authored by Mike Snitzer <snitzer [at] redhat.com> on Wed Jan 16 18:53:26 2019 -0500. The commit for this change in Linux stable tree is 57c3651 (patch).

dm: fix clone_bio() to trigger blk_recount_segments()

DM's clone_bio() now benefits from using bio_trim() by fixing the fact
that clone_bio() wasn't clearing BIO_SEG_VALID like bio_trim() does;
which triggers blk_recount_segments() via bio_phys_segments().

Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

There are 8 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 drivers/md/dm.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index d67c95e..fcb97b0 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1320,7 +1320,7 @@ static int clone_bio(struct dm_target_io *tio, struct bio *bio,

    __bio_clone_fast(clone, bio);

-   if (unlikely(bio_integrity(bio) != NULL)) {
+   if (bio_integrity(bio)) {
        int r;

        if (unlikely(!dm_target_has_integrity(tio->ti->type) &&
@@ -1336,11 +1336,7 @@ static int clone_bio(struct dm_target_io *tio, struct bio *bio,
            return r;
    }

-   bio_advance(clone, to_bytes(sector - clone->bi_iter.bi_sector));
-   clone->bi_iter.bi_size = to_bytes(len);
-
-   if (unlikely(bio_integrity(bio) != NULL))
-       bio_integrity_trim(clone);
+   bio_trim(clone, sector - clone->bi_iter.bi_sector, len);

    return 0;
 }

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