linux-ext4 - Re: [PATCH 4/4] ext3: Warn if mounting rw on a disk requiring stable page writes

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Date:	Wed, 21 Nov 2012 03:15:43 +0100
From:	Jan Kara <jack@...e.cz>
To:	"Darrick J. Wong" <darrick.wong@...cle.com>
Cc:	axboe@...nel.dk, lucho@...kov.net, jack@...e.cz, ericvh@...il.com,
	tytso@....edu, rminnich@...dia.gov, viro@...iv.linux.org.uk,
	martin.petersen@...cle.com, neilb@...e.de, david@...morbit.com,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	adilger.kernel@...ger.ca, bharrosh@...asas.com, jlayton@...ba.org,
	v9fs-developer@...ts.sourceforge.net, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 4/4] ext3: Warn if mounting rw on a disk requiring
 stable page writes

On Tue 20-11-12 18:00:56, Darrick J. Wong wrote:
> ext3 doesn't properly isolate pages from changes during writeback.  Since the
> recommended fix is to use ext4, for now we'll just print a warning if the user
> tries to mount in write mode.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
> ---
>  fs/ext3/super.c |    8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> 
> diff --git a/fs/ext3/super.c b/fs/ext3/super.c
> index 5366393..5b3725d 100644
> --- a/fs/ext3/super.c
> +++ b/fs/ext3/super.c
> @@ -1325,6 +1325,14 @@ static int ext3_setup_super(struct super_block *sb, struct ext3_super_block *es,
>  			"forcing read-only mode");
>  		res = MS_RDONLY;
>  	}
> +	if (!read_only &&
> +	    queue_requires_stable_pages(bdev_get_queue(sb->s_bdev))) {
> +		ext3_msg(sb, KERN_ERR,
> +			"error: ext3 cannot safely write data to a disk "
> +			"requiring stable pages writes; forcing read-only "
> +			"mode.  Upgrading to ext4 is recommended.");
> +		res = MS_RDONLY;
> +	}
>  	if (read_only)
>  		return res;
>  	if (!(sbi->s_mount_state & EXT3_VALID_FS))
  Why this? ext3 should be fixed by your change to
filemap_page_mkwrite()... Or does testing show otherwise?

								Honza
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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