Commit 892ad71f authored by Dennis Zhou's avatar Dennis Zhou Committed by Jens Axboe

dm: set the static flush bio device on demand

The next patch changes the macro bio_set_dev() to associate a bio with a
blkg based on the device set. However, dm creates a static bio to be
used as the basis for cloning empty flush bios on creation. The
bio_set_dev() call in alloc_dev() will cause problems with the next
patch adding association to bio_set_dev() because the call is before the
bdev is associated with a gendisk (bd_disk is %NULL). To get around
this, set the device on the static bio every time and use that to clone
to the other bios.
Signed-off-by: default avatarDennis Zhou <>
Acked-by: default avatarMike Snitzer <>
Cc: Alasdair Kergon <>
Signed-off-by: default avatarJens Axboe <>
parent 2268c0fe
......@@ -2021,6 +2021,7 @@ void bio_disassociate_blkg(struct bio *bio)
bio->bi_blkg = NULL;
* __bio_associate_blkg - associate a bio with the a blkg
......@@ -1417,10 +1417,21 @@ static int __send_empty_flush(struct clone_info *ci)
unsigned target_nr = 0;
struct dm_target *ti;
* Empty flush uses a statically initialized bio, &md->flush_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);
while ((ti = dm_table_get_target(ci->map, target_nr++)))
__send_duplicate_bios(ci, ti, ti->num_flush_bios, NULL);
return 0;
......@@ -1939,7 +1950,6 @@ static struct mapped_device *alloc_dev(int minor)
goto bad;
bio_init(&md->flush_bio, NULL, 0);
bio_set_dev(&md->flush_bio, md->bdev);
md->flush_bio.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC;
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