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

Dave Chinner
2013-07-25T04:11:24Z

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