mount.gfs2: Fix mounting of regular files with -o loop

When we use -o loop, mount(8) sets up the loop device and passes loop=/dev/loopN to mount.gfs2, which currently naively passes this option to mount(2). As gfs2 doesn't recognise the loop option, mounting fails with EINVAL.

This patch stops mount.gfs2 from passing loop=/dev/loopN to mount(2) to fix this problem and also makes sure this option appears in /etc/mtab so that umount(8) can automatically free up the loop device on unmount.

rhbz#729071

Signed-off-by Andrew Price <[email protected]>

---
 gfs2/mount/util.c |   29 ++++++++++++++++++++++++++---
 gfs2/mount/util.h |    1 +
 2 files changed, 27 insertions(+), 3 deletions(-)

gfs2/mount/util.c +26 -3

index 5a1f999..3884389 100644
@@ -150,6 +150,16 @@ void parse_opts(struct mount_options *mo)
 			continue;
 		}
 
+		/* mount(8) will have already set up the loop device for us so
+		   we can safely ignore the loop= option it provides and avoid
+		   getting an EINVAL from gfs2. However, we still need to make
+		   sure the option appears in mtab so that umount(8) can
+		   automatically free up the loop device. */
+		if (!strncmp("loop", o, 4)) {
+			strncpy(mo->loopopt, o, PATH_MAX);
+			continue;
+		}
+
 		if (extra_len + 1 + strlen(o) > PATH_MAX)
 			die("extra options string is too long\n");
 

@@ -261,6 +271,8 @@ void read_proc_mounts(struct mount_options *mo)
 	char save_opts[PATH_MAX];
 	char save_device[PATH_MAX];
 	int found = 0;
+	int freq = 0;
+	int passno = 0;
 	struct stat st_mo_dev, st_mounts_dev;
 
 	file = fopen("/proc/mounts", "r");

@@ -274,8 +286,14 @@ void read_proc_mounts(struct mount_options *mo)
 	}
 
 	while (fgets(line, PATH_MAX, file)) {
-		if (sscanf(line, "%s %s %s %s", device, path, type, opts) != 4)
-			continue;
+		if (mo->loopopt[0] == '\0') {
+			if (sscanf(line, "%s %s %s %s", device, path, type, opts) != 4)
+				continue;
+		} else {
+			if (sscanf(line, "%s %s %s %s %d %d",
+			           device, path, type, opts, &freq, &passno) != 6)
+				continue;
+		}
 		if (strcmp(path, mo->dir)) {
 			if (!strchr(path, '\\'))
 				continue;

@@ -301,7 +319,11 @@ void read_proc_mounts(struct mount_options *mo)
 
 		strncpy(save_device, device, PATH_MAX);
 		strncpy(save_opts, opts, PATH_MAX);
-		strncpy(save_line, line, PATH_MAX);
+		if (mo->loopopt[0] != '\0')
+			snprintf(save_line, PATH_MAX, "%s %s %s %s,%s %d %d\n",
+			         device, path, type, opts, mo->loopopt, freq, passno);
+		else
+			strncpy(save_line, line, PATH_MAX);
 		found = 1;
 	}
 

@@ -318,6 +340,7 @@ void read_proc_mounts(struct mount_options *mo)
 	log_debug("read_proc_mounts: device = \"%s\"", mo->specified_dev);
 	log_debug("read_proc_mounts: dm device = \"%s\"", mo->dev);
 	log_debug("read_proc_mounts: opts = \"%s\"", mo->opts);
+	log_debug("read_proc_mounts: proc_entry = \"%s\"", mo->proc_entry);
 }
 
 static void gfs2_inum_in(struct gfs2_inum *no, char *buf)

gfs2/mount/util.h +1 -0

index e866cd4..8b05aa5 100644
@@ -50,6 +50,7 @@ struct mount_options {
 	char dev[PATH_MAX+1];
 	char dir[PATH_MAX+1];
 	char opts[PATH_MAX+1];
+	char loopopt[PATH_MAX+1];
 	char hostdata[PATH_MAX+1];
 	char extra[PATH_MAX+1];
 	char extra_plus[PATH_MAX+1];

Hi,

Looks good to me. Did you test it with -o remount to be sure it does the right thing for that too?