From: Eric Sandeen <sandeen@redhat.com>
Subject: Re: [PATCH] e2image: Print a warning if running over a mounted filesystem
Date: Thu, 26 Sep 2013 17:12:37 -0500
Message-ID: <5244B155.6010102@redhat.com>
References: <1380229204-32526-1-git-send-email-cmaiolino@redhat.com>
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Cc: linux-ext4@vger.kernel.org
To: Carlos Maiolino <cmaiolino@redhat.com>
In-Reply-To: <1380229204-32526-1-git-send-email-cmaiolino@redhat.com>
Sender: linux-ext4-owner@vger.kernel.org

On 9/26/13 4:00 PM, Carlos Maiolino wrote:
> Several users use to run e2image over a mounted filesystem, providing
> inconsistent, useless e2images.
> This patch adds a warning in such cases, notifying the user and also adds a
> force option making e2image able to run over Read-only filesystems.

Good idea.  ;)  But I think it needs a manpage update as well.

If you use ext2fs_check_if_mounted() can you find out whether it's
mounted readonly, and allow it to proceed in that case?

(But I suppose that only checks one mount point, I'm not sure?)

-Eric

> Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
> ---
>  misc/Makefile.in |  2 +-
>  misc/e2image.c   | 18 ++++++++++++++++--
>  2 files changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/misc/Makefile.in b/misc/Makefile.in
> index 8a69855..2e20b25 100644
> --- a/misc/Makefile.in
> +++ b/misc/Makefile.in
> @@ -49,7 +49,7 @@ UUIDGEN_OBJS=	uuidgen.o
>  UUIDD_OBJS=	uuidd.o
>  DUMPE2FS_OBJS=	dumpe2fs.o
>  BADBLOCKS_OBJS=	badblocks.o
> -E2IMAGE_OBJS=	e2image.o
> +E2IMAGE_OBJS=	e2image.o ismounted.o
>  FSCK_OBJS=	fsck.o base_device.o ismounted.o
>  BLKID_OBJS=	blkid.o
>  FILEFRAG_OBJS=	filefrag.o
> diff --git a/misc/e2image.c b/misc/e2image.c
> index 885a794..6f6329a 100644
> --- a/misc/e2image.c
> +++ b/misc/e2image.c
> @@ -49,6 +49,8 @@ extern int optind;
>  
>  #define QCOW_OFLAG_COPIED     (1LL << 63)
>  
> +/* ismounted.h */
> +extern int is_mounted(const char *file);
>  
>  const char * program_name = "e2image";
>  char * device_name = NULL;
> @@ -87,7 +89,7 @@ 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);
>  }
> @@ -1255,6 +1257,7 @@ int main (int argc, char ** argv)
>  	int qcow2_fd = 0;
>  	int fd = 0;
>  	int ret = 0;
> +	int ignore_mounted = 0;
>  	struct stat st;
>  
>  #ifdef ENABLE_NLS
> @@ -1269,7 +1272,7 @@ 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 +1293,9 @@ int main (int argc, char ** argv)
>  		case 'a':
>  			all_data = 1;
>  			break;
> +		case 'f':
> +			ignore_mounted = 1;
> +			break;
>  		default:
>  			usage();
>  		}
> @@ -1305,6 +1311,14 @@ int main (int argc, char ** argv)
>  	device_name = argv[optind];
>  	image_fn = argv[optind+1];
>  
> +	if (is_mounted(device_name) && !ignore_mounted) {
> +		fprintf(stderr, "\nWarning: Running e2image on a mounted "
> +				"filesystem can result in an inconsistent "
> +				"image which will not be useful. 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);
>