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Commit bd4691a0 authored by Nikolay Borisov's avatar Nikolay Borisov Committed by David Sterba
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btrfs: Use ihold instead of igrab in cow_file_range_async 



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

Signed-off-by: default avatarNikolay Borisov <nborisov@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
[ add comment ]
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 62b37622

fs/btrfs/inode.c

+6 −1
Original line number Diff line number Diff line
@@ -1193,7 +1193,12 @@ static int cow_file_range_async(struct inode *inode, struct page *locked_page, 
	while (start < end) {

		async_cow = kmalloc(sizeof(*async_cow), GFP_NOFS);

		BUG_ON(!async_cow); /* -ENOMEM */

		async_cow->inode = igrab(inode);

		/*

		 * igrab is called higher up in the call chain, take only the

		 * lightweight reference for the callback lifetime

		 */

		ihold(inode);

		async_cow->inode = inode;

		async_cow->fs_info = fs_info;

		async_cow->locked_page = locked_page;

		async_cow->start = start;