btrfs: factor out low-level bio setup from submit_stripe_bio

Split out a low-level btrfs_submit_dev_bio helper that just submits
the bio without any cloning decisions or setting up the end I/O handler
for future reuse by a different caller.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/volumes.c

@@ -6749,28 +6749,8 @@ static void btrfs_clone_write_end_io(struct bio *bio)
 	bio_put(bio);
 }
 
-static void submit_stripe_bio(struct btrfs_io_context *bioc,
-			      struct bio *orig_bio, int dev_nr, bool clone)
+static void btrfs_submit_dev_bio(struct btrfs_device *dev, struct bio *bio)
 {
-	struct btrfs_fs_info *fs_info = bioc->fs_info;
-	struct btrfs_device *dev = bioc->stripes[dev_nr].dev;
-	u64 physical = bioc->stripes[dev_nr].physical;
-	struct bio *bio;
-
-	if (clone) {
-		bio = bio_alloc_clone(NULL, orig_bio, GFP_NOFS, &fs_bio_set);
-		bio_inc_remaining(orig_bio);
-		bio->bi_end_io = btrfs_clone_write_end_io;
-	} else {
-		bio = orig_bio;
-		btrfs_bio(bio)->device = dev;
-		bio->bi_end_io = btrfs_end_bio;
-	}
-
-	bioc->stripes[dev_nr].bioc = bioc;
-	bio->bi_private = &bioc->stripes[dev_nr];
-	bio->bi_iter.bi_sector = physical >> 9;
-
 	if (!dev || !dev->bdev ||
 	    test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state) ||
 	    (btrfs_op(bio) == BTRFS_MAP_WRITE &&
@@ -6786,8 +6766,11 @@ static void submit_stripe_bio(struct btrfs_io_context *bioc,
 	 * zone
 	 */
 	if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
+		u64 physical = bio->bi_iter.bi_sector << SECTOR_SHIFT;
+
 		if (btrfs_dev_is_sequential(dev, physical)) {
-			u64 zone_start = round_down(physical, fs_info->zone_size);
+			u64 zone_start = round_down(physical,
+						    dev->fs_info->zone_size);
 
 			bio->bi_iter.bi_sector = zone_start >> SECTOR_SHIFT;
 		} else {
@@ -6795,7 +6778,7 @@ static void submit_stripe_bio(struct btrfs_io_context *bioc,
 			bio->bi_opf |= REQ_OP_WRITE;
 		}
 	}
-	btrfs_debug_in_rcu(fs_info,
+	btrfs_debug_in_rcu(dev->fs_info,
 	"%s: rw %d 0x%x, sector=%llu, dev=%lu (%s id %llu), size=%u",
 		__func__, bio_op(bio), bio->bi_opf, bio->bi_iter.bi_sector,
 		(unsigned long)dev->bdev->bd_dev, rcu_str_deref(dev->name),
@@ -6805,6 +6788,28 @@ static void submit_stripe_bio(struct btrfs_io_context *bioc,
 	submit_bio(bio);
 }
 
+static void submit_stripe_bio(struct btrfs_io_context *bioc,
+			      struct bio *orig_bio, int dev_nr, bool clone)
+{
+	struct bio *bio;
+
+	/* Reuse the bio embedded into the btrfs_bio for the last mirror */
+	if (!clone) {
+		bio = orig_bio;
+		btrfs_bio(bio)->device = bioc->stripes[dev_nr].dev;
+		bio->bi_end_io = btrfs_end_bio;
+	} else {
+		bio = bio_alloc_clone(NULL, orig_bio, GFP_NOFS, &fs_bio_set);
+		bio_inc_remaining(orig_bio);
+		bio->bi_end_io = btrfs_clone_write_end_io;
+	}
+
+	bio->bi_private = &bioc->stripes[dev_nr];
+	bio->bi_iter.bi_sector = bioc->stripes[dev_nr].physical >> SECTOR_SHIFT;
+	bioc->stripes[dev_nr].bioc = bioc;
+	btrfs_submit_dev_bio(bioc->stripes[dev_nr].dev, bio);
+}
+
 void btrfs_submit_bio(struct btrfs_fs_info *fs_info, struct bio *bio, int mirror_num)
 {
 	u64 logical = bio->bi_iter.bi_sector << 9;