Btrfs: add write_flags for compression bio

Compression code path has only flaged bios with REQ_OP_WRITE no matter
where the bios come from, but it could be a sync write if fsync starts
this writeback or a normal writeback write if wb kthread starts a
periodic writeback.

It breaks the rule that sync writes and writeback writes need to be
differentiated from each other, because from the POV of block layer,
all bios need to be recognized by these flags in order to do some
management, e.g. throttlling.

This passes writeback_control to compression write path so that it can
send bios with proper flags to block layer.

Signed-off-by: Liu Bo <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index b35ce16..4a78e57 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -295,7 +295,8 @@ blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
 				 unsigned long len, u64 disk_start,
 				 unsigned long compressed_len,
 				 struct page **compressed_pages,
-				 unsigned long nr_pages)
+				 unsigned long nr_pages,
+				 unsigned int write_flags)
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	struct bio *bio = NULL;
@@ -327,7 +328,7 @@ blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
 	bdev = fs_info->fs_devices->latest_bdev;
 
 	bio = btrfs_bio_alloc(bdev, first_byte);
-	bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
+	bio->bi_opf = REQ_OP_WRITE | write_flags;
 	bio->bi_private = cb;
 	bio->bi_end_io = end_compressed_bio_write;
 	refcount_set(&cb->pending_bios, 1);
@@ -374,7 +375,7 @@ blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
 			bio_put(bio);
 
 			bio = btrfs_bio_alloc(bdev, first_byte);
-			bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
+			bio->bi_opf = REQ_OP_WRITE | write_flags;
 			bio->bi_private = cb;
 			bio->bi_end_io = end_compressed_bio_write;
 			bio_add_page(bio, page, PAGE_SIZE, 0);