btrfs: Remove fs_info from struct async_chunk

The associated btrfs_work already contains a reference to the fs_info so
use that instead of passing it via async_chunk. No functional changes.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/inode.c

@@ -357,7 +357,6 @@ struct async_extent {
 
 struct async_chunk {
 	struct inode *inode;
-	struct btrfs_fs_info *fs_info;
 	struct page *locked_page;
 	u64 start;
 	u64 end;
@@ -1147,13 +1146,11 @@ static noinline void async_cow_start(struct btrfs_work *work)
  */
 static noinline void async_cow_submit(struct btrfs_work *work)
 {
-	struct btrfs_fs_info *fs_info;
-	struct async_chunk *async_chunk;
+	struct async_chunk *async_chunk = container_of(work, struct async_chunk,
+						     work);
+	struct btrfs_fs_info *fs_info = btrfs_work_owner(work);
 	unsigned long nr_pages;
 
-	async_chunk = container_of(work, struct async_chunk, work);
-
-	fs_info = async_chunk->fs_info;
 	nr_pages = (async_chunk->end - async_chunk->start + PAGE_SIZE) >>
 		PAGE_SHIFT;
 
@@ -1244,7 +1241,6 @@ static int cow_file_range_async(struct inode *inode, struct page *locked_page,
 		async_chunk[i].inode = inode;
 		async_chunk[i].start = start;
 		async_chunk[i].end = cur_end;
-		async_chunk[i].fs_info = fs_info;
 		async_chunk[i].locked_page = locked_page;
 		async_chunk[i].write_flags = write_flags;
 		INIT_LIST_HEAD(&async_chunk[i].extents);