btrfs: drop bio_set_dev where not needed

bio_set_dev sets a bdev to a bio and is not only setting a pointer bug
also changing some state bits if there was a different bdev set before.
This is one thing that's not needed.

Another thing is that setting a bdev at bio allocation time is too early
and actually does not work with plain redundancy profiles, where each
time we submit a bio to a device, the bdev is set correctly.

In many places the bio bdev is set to latest_bdev that seems to serve as
a stub pointer "just to put something to bio". But we don't have to do
that.

Where do we know which bdev to set:

* for regular IO: submit_stripe_bio that's called by btrfs_map_bio

* repair IO: repair_io_failure, read or write from specific device

* super block write (using buffer_heads but uses raw bdev) and barriers

* scrub: this does not use all regular IO paths as it needs to reach all
  copies, verify and fixup eventually, and for that all bdev management
  is independent

* raid56: rbio_add_io_page, for the RMW write

* integrity-checker: does it's own low-level block tracking

Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 0 insertions, 1 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 9a2339a54a9d..c4fcfd7c8013 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2544,7 +2544,6 @@ struct bio *btrfs_create_repair_bio(struct inode *inode, struct bio *failed_bio,
 	bio = btrfs_io_bio_alloc(1);
 	bio->bi_end_io = endio_func;
 	bio->bi_iter.bi_sector = failrec->logical >> 9;
-	bio_set_dev(bio, fs_info->fs_devices->latest_bdev);
 	bio->bi_iter.bi_size = 0;
 	bio->bi_private = data;