Re: [PATCH 42/49] xfs: Validate log space at mount time

[Dave Chinner <david@fromorbit.com>]

On Fri, Jul 19, 2013 at 04:25:13PM +1000, Dave Chinner wrote:
> From: Jie Liu <jeff.liu@oracle.com>
> 
> Validate log space during log mount stage, the underlying function
> will drop a warning message via syslog in critical level if the log
> space is too small or too large.
> 
> [ dchinner: For CRC enable filesystems, abort the mounting of the
> filesystem as mkfs should never make a log too small for the given
> filesystem configuration. ]
> 
> Signed-off-by: Jie Liu <jeff.liu@oracle.com>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
>  fs/xfs/xfs_log.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 48 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
> index b02415b..64b1f01 100644
> --- a/fs/xfs/xfs_log.c
> +++ b/fs/xfs/xfs_log.c
> @@ -614,7 +614,9 @@ xfs_log_mount(
>  	xfs_daddr_t	blk_offset,
>  	int		num_bblks)
>  {
> -	int		error;
> +	int		error = 0;
> +	int		min_logfsbs;
> +	int		max_logfsbs;
>  
>  	if (!(mp->m_flags & XFS_MOUNT_NORECOVERY))
>  		xfs_notice(mp, "Mounting Filesystem");
> @@ -631,6 +633,51 @@ xfs_log_mount(
>  	}
>  
>  	/*
> +	 * Validate the given log space and drop a critical message via syslog
> +	 * if the log size is too small that would lead to some unexpected
> +	 * situations in transaction log space reservation stage.
> +	 *
> +	 * Note: we can't just reject the mount if the validation fails.  This
> +	 * would mean that people would have to downgrade their kernel just to
> +	 * remedy the situation as there is no way to grow the log (short of
> +	 * black magic surgery with xfs_db).
> +	 *
> +	 * We can, however, reject mounts for CRC format filesystems, as the
> +	 * mkfs binary being used to make the filesystem should never create a
> +	 * filesystem with a log that is too small.
> +	 */
> +	min_logfsbs = xfs_log_calc_minimum_size(mp);
> +	max_logfsbs = XFS_BB_TO_FSB(mp, XFS_MAX_LOG_BLOCKS);

Actually, that's busted:

XFS (vdc): Log size 521728 blocks too large, maximum size is 131072 blocks
XFS (vdc): Log size out of supported range.  Continuing onwards, but if log hangs are
experienced then please report this message in the bug report.

I'll need to revisit this.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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