tune2fs: warn if the filesystem journal is dirty

From: Jim Garlick <garlick@llnl.gov>

Running tune2fs on a filesystem with an unrecovered journal can
cause the tune2fs settings changes in the superblock to be reverted
when the journal is replayed if it contains an uncommitted copy of
the superblock.  Print a warning if this is detected so that the
user isn't surprised if it happens.

Signed-off-by: Jim Garlick <garlick@llnl.gov>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
---
 misc/tune2fs.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

On Fri, Sep 12, 2014 at 02:39:40PM -0600, Andreas Dilger wrote:
> From: Jim Garlick <garlick@llnl.gov>
> 
> Running tune2fs on a filesystem with an unrecovered journal can
> cause the tune2fs settings changes in the superblock to be reverted
> when the journal is replayed if it contains an uncommitted copy of
> the superblock.  Print a warning if this is detected so that the
> user isn't surprised if it happens.
> 
> Signed-off-by: Jim Garlick <garlick@llnl.gov>
> Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
> ---
>  misc/tune2fs.c |   12 ++++++++++++
>  1 files changed, 12 insertions(+), 0 deletions(-)
> 
> diff --git a/misc/tune2fs.c b/misc/tune2fs.c
> index b65dab9..e5ec8a4 100644
> --- a/misc/tune2fs.c
> +++ b/misc/tune2fs.c
> @@ -2395,6 +2395,7 @@ retry_open:
>  		ext2fs_mark_super_dirty(fs);
>  		printf(_("Setting stripe width to %d\n"), stripe_width);
>  	}
> +
>  	if (ext_mount_opts) {
>  		strncpy((char *)(fs->super->s_mount_opts), ext_mount_opts,
>  			sizeof(fs->super->s_mount_opts));
> @@ -2404,6 +2405,17 @@ retry_open:
>  		       ext_mount_opts);
>  		free(ext_mount_opts);
>  	}
> +
> +	/* Warn if file system needs recovery and it is opened for writing. */
> +	if ((open_flag & EXT2_FLAG_RW) && !(mount_flags & EXT2_MF_MOUNTED) &&
> +	    (sb->s_feature_compat & EXT3_FEATURE_COMPAT_HAS_JOURNAL) &&
> +	    (sb->s_feature_incompat & EXT3_FEATURE_INCOMPAT_RECOVER)) {
> +		fprintf(stderr,
> +			_("Warning: needs_recovery flag is set. You may wish\n"
> +			  "replay the journal then rerun this command, or any\n"
> +			  "changes may be overwritten by journal recovery.\n"));

At a bare minimum this ought to be "You may wish *to* replay...", but I
suggest:

"You should replay the journal and then rerun this command because it is
possible that your changes will be overwritten by the journal recovery."

Otherwise looks fine to me.

--D

> +	}
> +
>  	free(device_name);
>  	remove_error_table(&et_ext2_error_table);
>  
> -- 
> 1.7.3.4
> 
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