[Cluster-devel] [PATCH RHEL6] mount.gfs2: Fix mounting of regular files with -o loop

[Cluster-devel] [PATCH RHEL6] mount.gfs2: Fix mounting of regular files with -o loop

[Andrew Price]

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 <anprice@redhat.com>
---
 gfs2/mount/util.c |   29 ++++++++++++++++++++++++++---
 gfs2/mount/util.h |    1 +
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/gfs2/mount/util.c b/gfs2/mount/util.c
index 5a1f999..3884389 100644
--- a/gfs2/mount/util.c
+++ b/gfs2/mount/util.c
@@ -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)
diff --git a/gfs2/mount/util.h b/gfs2/mount/util.h
index e866cd4..8b05aa5 100644
--- a/gfs2/mount/util.h
+++ b/gfs2/mount/util.h
@@ -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];
-- 
1.7.1

[Cluster-devel] [PATCH RHEL6] mount.gfs2: Fix mounting of regular files with -o loop

[Steven Whitehouse]

Hi,

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

Steve.

On Wed, 2011-08-17 at 17:25 +0100, Andrew Price wrote:
> 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 <anprice@redhat.com>
> ---
>  gfs2/mount/util.c |   29 ++++++++++++++++++++++++++---
>  gfs2/mount/util.h |    1 +
>  2 files changed, 27 insertions(+), 3 deletions(-)
> 
> diff --git a/gfs2/mount/util.c b/gfs2/mount/util.c
> index 5a1f999..3884389 100644
> --- a/gfs2/mount/util.c
> +++ b/gfs2/mount/util.c
> @@ -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)
> diff --git a/gfs2/mount/util.h b/gfs2/mount/util.h
> index e866cd4..8b05aa5 100644
> --- a/gfs2/mount/util.h
> +++ b/gfs2/mount/util.h
> @@ -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];

[Cluster-devel] [PATCH RHEL6] mount.gfs2: Fix mounting of regular files with -o loop

[Andrew Price]

On 17/08/11 17:32, Steven Whitehouse wrote:
> Hi,
>
> Looks good to me. Did you test it with -o remount to be sure it does the
> right thing for that too?

Yep, testing with -o remount looks fine:

(I added the loop option when testing with remount just to check that it 
was completely ignored in the remount case and wasn't doubled up)

[root at rhel6-01 mount]# mount -o rw,loop,noatime sparse-file /mnt
[root at rhel6-01 mount]# mount | grep gfs2
/dev/loop0 on /mnt type gfs2 
(rw,noatime,localflocks,localcaching,loop=/dev/loop0)
[root at rhel6-01 mount]# mount -vv -o remount,ro,loop /mnt
mount /dev/loop0 /mnt
parse_opts: opts = 
"ro,remount,noatime,loop=/dev/loop0,localflocks,localcaching"
   set flag 1 for "ro", flags = 1
   set flag 20 for "remount", flags = 21
   set flag 400 for "noatime", flags = 421
   add extra localflocks
   add extra localcaching
parse_opts: flags = 421
parse_opts: extra = "localflocks,localcaching"
parse_opts: hostdata = ""
parse_opts: lockproto = ""
parse_opts: locktable = ""
mount(2) ok
read_proc_mounts: device = "/dev/loop0"
read_proc_mounts: dm device = "/dev/loop0"
read_proc_mounts: opts = "ro,noatime,localflocks,localcaching"
read_proc_mounts: proc_entry = "/dev/loop0 /mnt gfs2 
ro,noatime,localflocks,localcaching,loop=/dev/loop0 0 0
"
[root at rhel6-01 mount]# mount | grep gfs2
/dev/loop0 on /mnt type gfs2 
(ro,noatime,localflocks,localcaching,loop=/dev/loop0)

Andy