From bd4691a0e866e774c9690f09fec573e845495f91 Mon Sep 17 00:00:00 2001 From: Nikolay Borisov Date: Thu, 3 Jan 2019 10:50:01 +0200 Subject: [PATCH] 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: Nikolay Borisov Reviewed-by: David Sterba [ add comment ] Signed-off-by: David Sterba --- fs/btrfs/inode.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 3c11982d73f7..d548538d0b16 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -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;