linux-kernel - Re: [PATCH 4.4 48/91] ext4: fix inline data error paths

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Message-ID: <1489164532.2593.17.camel@decadent.org.uk>
Date:   Fri, 10 Mar 2017 16:48:52 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Cc:     stable@...r.kernel.org, Theodore Tso <tytso@....edu>
Subject: Re: [PATCH 4.4 48/91] ext4: fix inline data error paths

On Fri, 2017-03-10 at 10:08 +0100, Greg Kroah-Hartman wrote:
> 4.4-stable review patch.  If anyone has any objections, please let me
> know.
> 
> ------------------
> 
> From: Theodore Ts'o <tytso@....edu>
> 
> commit eb5efbcb762aee4b454b04f7115f73ccbcf8f0ef upstream.
> 
> The write_end() function must always unlock the page and drop its ref
> count, even on an error.

This looks like a theoretical rather than a real issue, because I can't
see how ext4_write_inline_data_end() ever returns an error code.

> Signed-off-by: Theodore Ts'o <tytso@....edu>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> 
> ---
>  fs/ext4/inline.c |    9 ++++++++-
>  fs/ext4/inode.c  |   20 +++++++++++++++-----
>  2 files changed, 23 insertions(+), 6 deletions(-)
> 
> --- a/fs/ext4/inline.c
> +++ b/fs/ext4/inline.c
> @@ -933,8 +933,15 @@ int ext4_da_write_inline_data_end(struct
> >  				  struct page *page)
>  {
>  	int i_size_changed = 0;
> +	int ret;
>  
> -	copied = ext4_write_inline_data_end(inode, pos, len, copied, page);
> +	ret = ext4_write_inline_data_end(inode, pos, len, copied, page);
> +	if (ret < 0) {
> +		unlock_page(page);
> +		put_page(page);
[...]

For 4.4 each put_page() should ideally be changed to
page_cache_release().  It makes no practical difference but would be
consistent with other paths.

Ben.

-- 
Ben Hutchings
If you seem to know what you are doing, you'll be given more to do.


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