Btrfs: add ref_count and free function for btrfs_bio

1: ref_count is simple than current RBIO_HOLD_BBIO_MAP_BIT flag
   to keep btrfs_bio's memory in raid56 recovery implement.
2: free function for bbio will make code clean and flexible, plus
   forced data type checking in compile.

Changelog v1->v2:
 Rename following by David Sterba's suggestion:
 put_btrfs_bio() -> btrfs_put_bio()
 get_btrfs_bio() -> btrfs_get_bio()
 bbio->ref_count -> bbio->refs

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 65bd285ef361..dab8af4450e1 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2058,7 +2058,7 @@ int repair_io_failure(struct inode *inode, u64 start, u64 length, u64 logical,
         sector = bbio->stripes[mirror_num-1].physical >> 9;
         bio->bi_iter.bi_sector = sector;
         dev = bbio->stripes[mirror_num-1].dev;
-        kfree(bbio);
+        btrfs_put_bbio(bbio);
         if (!dev || !dev->bdev || !dev->writeable) {
                 bio_put(bio);
                 return -EIO;