linux-ext4 - Re: [PATCH] e2image: Print a warning if running over a mounted filesystem

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Message-ID: <20130927200057.GA15238@orion.maiolino.org>
Date:	Fri, 27 Sep 2013 17:00:58 -0300
From:	Carlos Maiolino <cmaiolino@...hat.com>
To:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH] e2image: Print a warning if running over a mounted
 filesystem

I'm so Sorry, I forgot to add a  V3 tag in the subject

On Fri, Sep 27, 2013 at 04:01:35PM -0300, Carlos Maiolino wrote:
> Several users use to run e2image over a mounted RW filesystem, providing
> inconsistent, useless e2images for debugging purposes.
> This patch adds a warning in such cases, notifying the user and also adds a
> force option making e2image able to run in such cases.
> Also print a warning when not using qcow or raw formats but allows image
> creation to proceed, since, such images might be used for metadata backup
> purposes.
> 
> Signed-off-by: Carlos Maiolino <cmaiolino@...hat.com>
> ---
>  misc/e2image.c | 34 ++++++++++++++++++++++++++++++++--
>  1 file changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/misc/e2image.c b/misc/e2image.c
> index 885a794..e467301 100644
> --- a/misc/e2image.c
> +++ b/misc/e2image.c
> @@ -87,7 +87,7 @@ static int get_bits_from_size(size_t size)
>  
>  static void usage(void)
>  {
> -	fprintf(stderr, _("Usage: %s [-rsIQa] device image_file\n"),
> +	fprintf(stderr, _("Usage: %s [-rsIQaf] device image_file\n"),
>  		program_name);
>  	exit (1);
>  }
> @@ -1252,9 +1252,11 @@ int main (int argc, char ** argv)
>  	int open_flag = EXT2_FLAG_64BITS;
>  	int img_type = 0;
>  	int flags = 0;
> +	int mount_flags = 0;
>  	int qcow2_fd = 0;
>  	int fd = 0;
>  	int ret = 0;
> +	int ignore_rw_mount = 0;
>  	struct stat st;
>  
>  #ifdef ENABLE_NLS
> @@ -1269,7 +1271,7 @@ int main (int argc, char ** argv)
>  	if (argc && *argv)
>  		program_name = *argv;
>  	add_error_table(&et_ext2_error_table);
> -	while ((c = getopt(argc, argv, "rsIQa")) != EOF)
> +	while ((c = getopt(argc, argv, "rsIQaf")) != EOF)
>  		switch (c) {
>  		case 'I':
>  			flags |= E2IMAGE_INSTALL_FLAG;
> @@ -1290,6 +1292,9 @@ int main (int argc, char ** argv)
>  		case 'a':
>  			all_data = 1;
>  			break;
> +		case 'f':
> +			ignore_rw_mount = 1;
> +			break;
>  		default:
>  			usage();
>  		}
> @@ -1305,6 +1310,31 @@ int main (int argc, char ** argv)
>  	device_name = argv[optind];
>  	image_fn = argv[optind+1];
>  
> +	ext2fs_check_if_mounted(device_name, &mount_flags);
> +
> +	if ((mount_flags & EXT2_MF_MOUNTED) &&
> +	   !(mount_flags & EXT2_MF_READONLY)) {
> +		fprintf(stderr, "\nWarning: Running e2image on a mounted "
> +				"RW filesystem can result in an inconsistent "
> +				"image which will not be useful for "
> +				"debugging purposes.\n");
> +		/*
> +		 * A force is required here once qcow and raw image
> +		 * formats (img_type is set) are mostly used for
> +		 * debugging purposes, while, a "normal" image is
> +		 * usually collected for metadata backup.
> +		 *
> +		 * An inconsistent image is almost useless for
> +		 * debugging, so we ensure the filesystem is read-only
> +		 * before continue (unless the user force the image creation)
> +		 */
> +		if (img_type && !ignore_rw_mount) {
> +			fprintf(stderr, "Use -f option if you really want to "
> +					"do that.\n");
> +			exit(1);
> +		}
> +	}
> +
>  	if (flags & E2IMAGE_INSTALL_FLAG) {
>  		install_image(device_name, image_fn, img_type);
>  		exit (0);
> -- 
> 1.8.1.4
> 
> --
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-- 
Carlos
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