[PATCH 3/7] btrfs: Use ihold instead of igrab in cow_file_range_async

[Nikolay Borisov <nborisov@suse.com>]

ihold is supposed to be used when the caller already has a reference to
the inode. In the case of cow_file_range_async this invariants holds,
since the 3 call chains leading to this function all take a reference:

btrfs_writepage  <--- does igrab
 extent_write_full_page
  __extent_writepage
   writepage_delalloc
     btrfs_run_delalloc_range
      cow_file_range_async

extent_write_cache_pages <--- does igrab
 __extent_writepage (same callchain as above)

and

submit_compressed_extents <-- already called from async CoW submit path,
			      which would have done ihold.
 extent_write_locked_range
  __extent_writepage

No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
---
 fs/btrfs/inode.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 97ad494d0b3c..f023d2b5ef49 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1194,7 +1194,8 @@ static int cow_file_range_async(struct inode *inode, struct page *locked_page,
 		async_cow = kmalloc(sizeof(*async_cow), GFP_NOFS);
 		if (!async_cow)
 			return -ENOMEM;
-		async_cow->inode = igrab(inode);
+		ihold(inode);
+		async_cow->inode = inode;
 		async_cow->fs_info = fs_info;
 		async_cow->locked_page = locked_page;
 		async_cow->start = start;
-- 
2.17.1