dm: simplify flush_bio initialization in __send_empty_flush

We don't really need the struct block_device to initialize a bio.  So
switch from using bio_set_dev to manually setting up bi_disk (bi_partno
will always be zero and has been cleared by bio_init already).

Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 54739f1b579bc8cc95d88ce8e7760b1516497d8c..6d7eb72d41f9ea741f989701c45f8c0a2d9d3df1 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1422,18 +1422,12 @@ static int __send_empty_flush(struct clone_info *ci)
         */
        bio_init(&flush_bio, NULL, 0);
        flush_bio.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC;
+       flush_bio.bi_disk = ci->io->md->disk;
+       bio_associate_blkg(&flush_bio);
+
        ci->bio = &flush_bio;
        ci->sector_count = 0;
 
-       /*
-        * Empty flush uses a statically initialized bio, as the base for
-        * cloning.  However, blkg association requires that a bdev is
-        * associated with a gendisk, which doesn't happen until the bdev is
-        * opened.  So, blkg association is done at issue time of the flush
-        * rather than when the device is created in alloc_dev().
-        */
-       bio_set_dev(ci->bio, ci->io->md->bdev);
-
        BUG_ON(bio_has_data(ci->bio));
        while ((ti = dm_table_get_target(ci->map, target_nr++)))
                __send_duplicate_bios(ci, ti, ti->num_flush_bios, NULL);