btrfs: fix direct I/O writes for split bios on zoned devices

When a bio is split in btrfs_submit_direct, dip->file_offset contains
the file offset for the first bio.  But this means the start value used
in btrfs_end_dio_bio to record the write location for zone devices is
incorrect for subsequent bios.

CC: stable@vger.kernel.org # 5.16+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/inode.c

@@ -7865,6 +7865,7 @@ static blk_status_t btrfs_submit_bio_start_direct_io(struct inode *inode,
 static void btrfs_end_dio_bio(struct bio *bio)
 {
 	struct btrfs_dio_private *dip = bio->bi_private;
+	struct btrfs_bio *bbio = btrfs_bio(bio);
 	blk_status_t err = bio->bi_status;
 
 	if (err)
@@ -7875,12 +7876,12 @@ static void btrfs_end_dio_bio(struct bio *bio)
 			   bio->bi_iter.bi_size, err);
 
 	if (bio_op(bio) == REQ_OP_READ)
-		err = btrfs_check_read_dio_bio(dip, btrfs_bio(bio), !err);
+		err = btrfs_check_read_dio_bio(dip, bbio, !err);
 
 	if (err)
 		dip->dio_bio->bi_status = err;
 
-	btrfs_record_physical_zoned(dip->inode, dip->file_offset, bio);
+	btrfs_record_physical_zoned(dip->inode, bbio->file_offset, bio);
 
 	bio_put(bio);
 	btrfs_dio_private_put(dip);