[PATCH resubmit 1/1] Add additional error text for missing mount.cifs

[Mike Pagano]

If a cifs mount is attempted without mount.cifs present on the
system the following appears via dmesg:

[ 25.949378] CIFS VFS: No username specified

The purpose of this patch is to better inform the user of the
possible cause of the error and show a potential solution.

The output for this error condition will look approximately like this:

[ 11.183392] CIFS VFS: No username specified. Could not find
/sbin/mount.cifs. Please ensure your system has this userspace program
installed.

Signed-off-by: Mike Pagano <mpagano-aBrp7R+bbdUdnm+***@public.gmane.org>
---
fs/cifs/connect.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 8813ff7..2091709 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -3359,6 +3359,7 @@ cifs_setup_volume_info(struct smb_vol *volume_info, char *mount_data,
const char *devname)
{
int rc = 0;
+ struct path path;

if (cifs_parse_mount_options(mount_data, devname, volume_info))
return -EINVAL;
@@ -3371,7 +3372,15 @@ cifs_setup_volume_info(struct smb_vol *volume_info, char *mount_data,
/* BB fixme parse for domain name here */
cifs_dbg(FYI, "Username: %s\n", volume_info->username);
} else {
- cifs_dbg(VFS, "No username specified\n");
+ /* As an extra step, check for missing /sbin/mount.cifs. Append
+ to error message as we cannot guarantee the location of this
+ binary in userspace */
+ if (kern_path("/sbin/mount.cifs", 0, &path)) {
+ cifs_dbg(VFS, "No username specified. Could not find /sbin/mount.cifs. Please ensure your system has this userspace program installed.\n");
+ }
+ else {
+ cifs_dbg(VFS, "No username specified\n");
+ }
/* In userspace mount helper we can get user name from alternate
locations such as env variables and files on disk */
return -EINVAL;
--
1.8.3.2

[Jeff Layton]

On Wed, 23 Apr 2014 14:40:56 -0400

Post by Mike Pagano
If a cifs mount is attempted without mount.cifs present on the
[ 25.949378] CIFS VFS: No username specified
The purpose of this patch is to better inform the user of the
possible cause of the error and show a potential solution.
[ 11.183392] CIFS VFS: No username specified. Could not find
/sbin/mount.cifs. Please ensure your system has this userspace program
installed.
---
fs/cifs/connect.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 8813ff7..2091709 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -3359,6 +3359,7 @@ cifs_setup_volume_info(struct smb_vol *volume_info, char *mount_data,
const char *devname)
{
int rc = 0;
+ struct path path;
if (cifs_parse_mount_options(mount_data, devname, volume_info))
return -EINVAL;
@@ -3371,7 +3372,15 @@ cifs_setup_volume_info(struct smb_vol *volume_info, char *mount_data,
/* BB fixme parse for domain name here */
cifs_dbg(FYI, "Username: %s\n", volume_info->username);
} else {
- cifs_dbg(VFS, "No username specified\n");
+ /* As an extra step, check for missing /sbin/mount.cifs. Append
+ to error message as we cannot guarantee the location of this
+ binary in userspace */
+ if (kern_path("/sbin/mount.cifs", 0, &path)) {

Ugh, no -- a pathwalk has no business here, IMO.

Post by Mike Pagano
+ cifs_dbg(VFS, "No username specified. Could not find /sbin/mount.cifs. Please ensure your system has this userspace program installed.\n");
+ }
+ else {
+ cifs_dbg(VFS, "No username specified\n");
+ }
/* In userspace mount helper we can get user name from alternate
locations such as env variables and files on disk */
return -EINVAL;
--
1.8.3.2
--
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I dunno. This doesn't seem like it's fixing a real problem to me.

While we highly recommend that people use the mount helper. It's not
specifically *required* per-se. If you can roll up the right mount
options and hand them to the kernel then there's no real problem.

If you really want this sort of warning, why not put it
into /bin/mount? Then you could even output the warning message to the
terminal instead of the kernel's ring buffer.

[Steve French]

Post by Jeff Layton
On Wed, 23 Apr 2014 14:40:56 -0400

Post by Mike Pagano
If a cifs mount is attempted without mount.cifs present on the
[ 25.949378] CIFS VFS: No username specified
The purpose of this patch is to better inform the user of the
possible cause of the error and show a potential solution.
[ 11.183392] CIFS VFS: No username specified. Could not find
/sbin/mount.cifs. Please ensure your system has this userspace program
installed.

<snip>

Post by Jeff Layton
I dunno. This doesn't seem like it's fixing a real problem to me.
While we highly recommend that people use the mount helper. It's not
specifically *required* per-se. If you can roll up the right mount
options and hand them to the kernel then there's no real problem.
If you really want this sort of warning, why not put it
into /bin/mount? Then you could even output the warning message to the
terminal instead of the kernel's ring buffer.

I don't have a strong opinion on this, although the patch is probably
harmless. I slightly prefer that it go in /bin/mount instead of
mount.cifs but would reconsider if new arguments in favor of it going
in the kernel