linux-ext4 - Re: [PATCH] ext4: fix warning when turn on dioread_nolock and inline

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Date:   Thu, 4 Jul 2019 16:55:14 +0200
From:   Jan Kara <jack@...e.cz>
To:     yangerkun <yangerkun@...wei.com>
Cc:     tytso@....edu, Jan Kara <jack@...e.com>, houtao1@...wei.com,
        miaoxie@...wei.com, yi.zhang@...wei.com, linux-ext4@...r.kernel.org
Subject: Re: [PATCH] ext4: fix warning when turn on dioread_nolock and
 inline_data

On Thu 04-07-19 20:50:32, yangerkun wrote:
> mkfs.ext4 -O inline_data /dev/vdb
> mount -o dioread_nolock /dev/vdb /mnt
> echo "some inline data..." >> /mnt/test-file
> echo "some inline data..." >> /mnt/test-file
> sync
> 
> With upon script, system will trigger
> "WARN_ON(!io_end->handle && sbi->s_journal)" since the wrong order
> between rsv_blocks calculate and destroy inline data for dealloc.

Thanks for the patch! Good catch! I'd just rephrase the last paragraph as:

The above script will trigger "WARN_ON(!io_end->handle && sbi->s_journal)"
because ext4_should_dioread_nolock() returns false for a file with inline
data. Move the check to a place after we have already removed the inline
data and prepared inode to write normal pages.

Otherwise the patch looks good to me so feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> 
> Signed-off-by: yangerkun <yangerkun@...wei.com>
> ---
>  fs/ext4/inode.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index c7f77c6..3f2a366 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -2769,15 +2769,6 @@ static int ext4_writepages(struct address_space *mapping,
>  		goto out_writepages;
>  	}
>  
> -	if (ext4_should_dioread_nolock(inode)) {
> -		/*
> -		 * We may need to convert up to one extent per block in
> -		 * the page and we may dirty the inode.
> -		 */
> -		rsv_blocks = 1 + ext4_chunk_trans_blocks(inode,
> -						PAGE_SIZE >> inode->i_blkbits);
> -	}
> -
>  	/*
>  	 * If we have inline data and arrive here, it means that
>  	 * we will soon create the block for the 1st page, so
> @@ -2796,6 +2787,15 @@ static int ext4_writepages(struct address_space *mapping,
>  		ext4_journal_stop(handle);
>  	}
>  
> +	if (ext4_should_dioread_nolock(inode)) {
> +		/*
> +		 * We may need to convert up to one extent per block in
> +		 * the page and we may dirty the inode.
> +		 */
> +		rsv_blocks = 1 + ext4_chunk_trans_blocks(inode,
> +						PAGE_SIZE >> inode->i_blkbits);
> +	}
> +
>  	if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
>  		range_whole = 1;
>  
> -- 
> 2.7.4
> 
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR