btrfs: Document logic regarding inode in async_cow_submit

Add a comment explaining when ->inode could be NULL and why we always
perform the ->async_delalloc_pages modification.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Nikolay Borisov 2019-01-03 10:50:03 +02:00 committed by David Sterba
parent a1d64ba609
commit 4546d17874
1 changed files with 6 additions and 0 deletions

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@ -1165,6 +1165,12 @@ static noinline void async_cow_submit(struct btrfs_work *work)
5 * SZ_1M)
cond_wake_up_nomb(&fs_info->async_submit_wait);
/*
* ->inode could be NULL if async_cow_start has failed to compress,
* in which case we don't have anything to submit, yet we need to
* always adjust ->async_delalloc_pages as its paired with the init
* happening in cow_file_range_async
*/
if (async_cow->inode)
submit_compressed_extents(async_cow);
}