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Subject: Re: [PATCH] btrfs: check return value of filemap_fdatawrite_range()
To:     Alex Dewar <alex.dewar90@gmail.com>, Chris Mason <clm@fb.com>,
        David Sterba <dsterba@suse.com>,
        Goldwyn Rodrigues <rgoldwyn@suse.com>,
        linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20200821124154.10218-1-alex.dewar90@gmail.com>
From:   Josef Bacik <josef@toxicpanda.com>
Message-ID: <c3c0ddbe-e225-22a4-c9bf-9317a50c211b@toxicpanda.com>
Date:   Fri, 21 Aug 2020 10:11:44 -0400
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On 8/21/20 8:41 AM, Alex Dewar wrote:
> In btrfs_dio_imap_begin(), filemap_fdatawrite_range() is called without
> checking the return value. Add a check to catch errors.
> 
> Fixes: c0aaf9b7a114f ("btrfs: switch to iomap_dio_rw() for dio")
> Addresses-Coverity: ("Unused value")
> Signed-off-by: Alex Dewar <alex.dewar90@gmail.com>
> ---
>   fs/btrfs/inode.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 7b57aaa1f9acc..38fde20b4a81b 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -7347,9 +7347,12 @@ static int btrfs_dio_iomap_begin(struct inode *inode, loff_t start,
>   	 * outstanding dirty pages are on disk.
>   	 */
>   	if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
> -		     &BTRFS_I(inode)->runtime_flags))
> +		     &BTRFS_I(inode)->runtime_flags)) {
>   		ret = filemap_fdatawrite_range(inode->i_mapping, start,
>   					       start + length - 1);
> +		if (ret)
> +			return ret;
> +	}
>   
>   	dio_data = kzalloc(sizeof(*dio_data), GFP_NOFS);
>   	if (!dio_data)
> 

Had to check to make sure there's no cleanup that's needed, there isn't, 
you can add

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Thanks,

Josef