linux-ext4 - Re: [PATCH 1/3] ext4: Wait for outstanding dio during truncate in nojournal mode

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Message-ID: <20190521180737.GA31888@iweiny-DESK2.sc.intel.com>
Date:   Tue, 21 May 2019 11:07:38 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     Jan Kara <jack@...e.cz>
Cc:     Ted Tso <tytso@....edu>, linux-ext4@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH 1/3] ext4: Wait for outstanding dio during truncate in
 nojournal mode

On Tue, May 21, 2019 at 09:43:56AM +0200, Jan Kara wrote:
> We didn't wait for outstanding direct IO during truncate in nojournal
> mode (as we skip orphan handling in that case). This can lead to fs
> corruption or stale data exposure if truncate ends up freeing blocks
> and these get reallocated before direct IO finishes. Fix the condition
> determining whether the wait is necessary.
> 
> CC: stable@...r.kernel.org
> Fixes: 1c9114f9c0f1 ("ext4: serialize unlocked dio reads with truncate")
> Signed-off-by: Jan Kara <jack@...e.cz>

Reviewed-by: Ira Weiny <ira.weiny@...el.com>

> ---
>  fs/ext4/inode.c | 21 +++++++++------------
>  1 file changed, 9 insertions(+), 12 deletions(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 82298c63ea6d..9bcb7f2b86dd 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -5630,20 +5630,17 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
>  				goto err_out;
>  			}
>  		}
> -		if (!shrink)
> +		if (!shrink) {
>  			pagecache_isize_extended(inode, oldsize, inode->i_size);
> -
> -		/*
> -		 * Blocks are going to be removed from the inode. Wait
> -		 * for dio in flight.  Temporarily disable
> -		 * dioread_nolock to prevent livelock.
> -		 */
> -		if (orphan) {
> -			if (!ext4_should_journal_data(inode)) {
> -				inode_dio_wait(inode);
> -			} else
> -				ext4_wait_for_tail_page_commit(inode);
> +		} else {
> +			/*
> +			 * Blocks are going to be removed from the inode. Wait
> +			 * for dio in flight.
> +			 */
> +			inode_dio_wait(inode);
>  		}
> +		if (orphan && ext4_should_journal_data(inode))
> +			ext4_wait_for_tail_page_commit(inode);
>  		down_write(&EXT4_I(inode)->i_mmap_sem);
>  
>  		rc = ext4_break_layouts(inode);
> -- 
> 2.16.4
>