Re: [PATCH] Btrfs: fix btrfs_wait_ordered_range() so that it waits for all ordered extents

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

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On 2020/2/13 下午8:29, fdmanana@kernel.org wrote:
> From: Filipe Manana <fdmanana@suse.com>
> 
> In btrfs_wait_ordered_range() once we find an ordered extent that has
> finished with an error we exit the loop and don't wait for any other
> ordered extents that might be still in progress.
> 
> All the users of btrfs_wait_ordered_range() expect that there are no more
> ordered extents in progress after that function returns. So past fixes
> such like the ones from the two following commits:
> 
>   ff612ba7849964 ("btrfs: fix panic during relocation after ENOSPC before
>                    writeback happens")
> 
>   28aeeac1dd3080 ("Btrfs: fix panic when starting bg cache writeout after
>                    IO error")
> 
> don't work when there are multiple ordered extents in the range.
> 
> Fix that by making btrfs_wait_ordered_range() wait for all ordered extents
> even after it finds one that had an error.
> 
> Link: https://github.com/kdave/btrfs-progs/issues/228#issuecomment-569777554
> Signed-off-by: Filipe Manana <fdmanana@suse.com>

Reviewed-by: Qu Wenruo <wqu@suse.com>

Thanks,
Qu
> ---
>  fs/btrfs/ordered-data.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
> index 4cbb4e082800..ab3711328e7d 100644
> --- a/fs/btrfs/ordered-data.c
> +++ b/fs/btrfs/ordered-data.c
> @@ -686,10 +686,15 @@ int btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len)
>  		}
>  		btrfs_start_ordered_extent(inode, ordered, 1);
>  		end = ordered->file_offset;
> +		/*
> +		 * If the ordered extent had an error save the error but don't
> +		 * exit without waiting first for all other ordered extents in
> +		 * the range to complete.
> +		 */
>  		if (test_bit(BTRFS_ORDERED_IOERR, &ordered->flags))
>  			ret = -EIO;
>  		btrfs_put_ordered_extent(ordered);
> -		if (ret || end == 0 || end == start)
> +		if (end == 0 || end == start)
>  			break;
>  		end--;
>  	}
> 


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