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

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Message-Id: <1380308495-3956-1-git-send-email-cmaiolino@redhat.com>
Date:	Fri, 27 Sep 2013 16:01:35 -0300
From:	Carlos Maiolino <cmaiolino@...hat.com>
To:	linux-ext4@...r.kernel.org
Subject: [PATCH] e2image: Print a warning if running over a mounted filesystem

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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