[PATCH 0/1] Normalized path names on umounts (take 2)

[PATCH 0/1] Normalized path names on umounts (take 2)

[Steve Dickson]

There is a second attempted at making paths in the
device names that have multiple slashes or no slash
at all unmount-able, without breaking any APIs.

Due to the way entries are written to both the /etc/mtab
and /proc/mounts, multiple slash have to be stripped and
leading slash have to be added (when they don't exist) 
on v4 mounts. With v3 mounts this normalization can 
not occur since those entries are always in the same format.

Finally, this normalization only needs to happen
when the mtab and /proc/mounts are not the same file.

Steve Dickson (1):
  umount.nfs: normalize path names during umounts.

 utils/mount/nfsumount.c |   64 +++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 62 insertions(+), 2 deletions(-)

[PATCH 1/1] umount.nfs: normalize path names during umounts.

[Steve Dickson]

So path names are found during umounts, normalize
path names by removing any extra slashes and add
a lead slash if one does not exist.

This normalization only has to occur when the mtab
and /proc/mounts are not the same file.

Signed-off-by: Steve Dickson <steved@redhat.com>
---
 utils/mount/nfsumount.c |   64 +++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 62 insertions(+), 2 deletions(-)

diff --git a/utils/mount/nfsumount.c b/utils/mount/nfsumount.c
index 3538d88..0f77261 100644
--- a/utils/mount/nfsumount.c
+++ b/utils/mount/nfsumount.c
@@ -140,6 +140,52 @@ static int del_mtab(const char *spec, const char *node)
 }
 
 /*
+ * To ensure the path is found during unmounts, strip
+ * off the multiple '/' or add a '/' if one does not exist.
+ */
+static inline char *
+normalize_path(char *spec) 
+{
+	char *colen, *ptr, *str, *dev;
+
+	if ((colen = strchr(spec, ':')) == NULL)
+		return NULL;
+
+	if (*(colen + 1) != '/') {
+		dev = str = malloc(strlen(spec) + 2);
+		if (dev == NULL) 
+			return NULL;
+
+		ptr = spec;
+		while (ptr <= colen)
+			*(str++) = *(ptr++);
+		*str++='/';
+		while (*ptr)
+			*(str++) = *(ptr++);
+		*str='\0';
+
+		return dev;
+	}
+
+	if (strstr(spec, "//") != NULL) {
+		dev = strdup(spec);
+		if (dev == NULL)
+			return NULL;
+
+		colen = strchr(dev, ':');
+		ptr = (colen +1);
+		while (*ptr && *(ptr+1) == '/')
+			ptr++;
+		while (*ptr)
+			*(++colen) = *(ptr++);
+		*(colen+1) = '\0';
+
+		return dev;
+	} 
+	return NULL;
+}
+
+/*
  * Detect NFSv4 mounts.
  *
  * Consult /proc/mounts to determine if the mount point
@@ -154,6 +200,7 @@ static int nfs_umount_is_vers4(const struct mntentchn *mc)
 	struct mntentchn *pmc;
 	struct mount_options *options;
 	int retval;
+	char *normpath=NULL;
 
 	retval = -1;
 	pmc = getprocmntdirbackward(mc->m.mnt_dir, NULL);
@@ -171,8 +218,20 @@ static int nfs_umount_is_vers4(const struct mntentchn *mc)
 		 */
 		while (pmc->m.mnt_fsname[nlen - 1] == '/')
 			nlen--;
-		if (strncmp(pmc->m.mnt_fsname, mc->m.mnt_fsname, nlen) != 0)
-			continue;
+		/*
+		 * When the mtab and /proc/mounts are not the same
+		 * file, normalize the path in the mtab if needed.
+		 */
+		if (mtab_is_writable())
+			normpath = normalize_path(mc->m.mnt_fsname);
+
+		if (strncmp(pmc->m.mnt_fsname, mc->m.mnt_fsname, nlen) != 0) {
+			/* Is there a normalized path, if so compare that one too */
+			if (normpath == NULL)
+				continue;
+			if (strncmp(pmc->m.mnt_fsname, normpath, nlen) != 0)
+				continue;
+		}
 
 		if (strcmp(pmc->m.mnt_type, "nfs4") == 0)
 			goto out_nfs4;
@@ -209,6 +268,7 @@ out_nfs:
 	retval = 0;
 
 out:
+	free(normpath);
 	return retval;
 }
 
-- 
1.7.1

Re: [PATCH 1/1] umount.nfs: normalize path names during umounts.

[Malahal Naineni]

Steve Dickson [steved@redhat.com] wrote:
> So path names are found during umounts, normalize
> path names by removing any extra slashes and add
> a lead slash if one does not exist.
> 
> This normalization only has to occur when the mtab
> and /proc/mounts are not the same file.
> 
> Signed-off-by: Steve Dickson <steved@redhat.com>
> ---
>  utils/mount/nfsumount.c |   64 +++++++++++++++++++++++++++++++++++++++++++++-
>  1 files changed, 62 insertions(+), 2 deletions(-)
> 
> diff --git a/utils/mount/nfsumount.c b/utils/mount/nfsumount.c
> index 3538d88..0f77261 100644
> --- a/utils/mount/nfsumount.c
> +++ b/utils/mount/nfsumount.c
> @@ -140,6 +140,52 @@ static int del_mtab(const char *spec, const char *node)
>  }
> 
>  /*
> + * To ensure the path is found during unmounts, strip
> + * off the multiple '/' or add a '/' if one does not exist.
> + */
> +static inline char *
> +normalize_path(char *spec) 
> +{
> +	char *colen, *ptr, *str, *dev;
> +
> +	if ((colen = strchr(spec, ':')) == NULL)
> +		return NULL;
> +
> +	if (*(colen + 1) != '/') {
> +		dev = str = malloc(strlen(spec) + 2);
> +		if (dev == NULL) 
> +			return NULL;
> +
> +		ptr = spec;
> +		while (ptr <= colen)
> +			*(str++) = *(ptr++);
> +		*str++='/';
> +		while (*ptr)
> +			*(str++) = *(ptr++);
> +		*str='\0';
> +
> +		return dev;
> +	}
> +
> +	if (strstr(spec, "//") != NULL) {
> +		dev = strdup(spec);
> +		if (dev == NULL)
> +			return NULL;
> +
> +		colen = strchr(dev, ':');
> +		ptr = (colen +1);
> +		while (*ptr && *(ptr+1) == '/')
> +			ptr++;
> +		while (*ptr)
> +			*(++colen) = *(ptr++);
> +		*(colen+1) = '\0';
> +
> +		return dev;
> +	} 
> +	return NULL;
> +}
> +
> +/*
>   * Detect NFSv4 mounts.
>   *
>   * Consult /proc/mounts to determine if the mount point
> @@ -154,6 +200,7 @@ static int nfs_umount_is_vers4(const struct mntentchn *mc)
>  	struct mntentchn *pmc;
>  	struct mount_options *options;
>  	int retval;
> +	char *normpath=NULL;
> 
>  	retval = -1;
>  	pmc = getprocmntdirbackward(mc->m.mnt_dir, NULL);
> @@ -171,8 +218,20 @@ static int nfs_umount_is_vers4(const struct mntentchn *mc)
>  		 */
>  		while (pmc->m.mnt_fsname[nlen - 1] == '/')
>  			nlen--;
> -		if (strncmp(pmc->m.mnt_fsname, mc->m.mnt_fsname, nlen) != 0)
> -			continue;
> +		/*
> +		 * When the mtab and /proc/mounts are not the same
> +		 * file, normalize the path in the mtab if needed.
> +		 */
> +		if (mtab_is_writable())
> +			normpath = normalize_path(mc->m.mnt_fsname);
> +
> +		if (strncmp(pmc->m.mnt_fsname, mc->m.mnt_fsname, nlen) != 0) {
> +			/* Is there a normalized path, if so compare that one too */
> +			if (normpath == NULL)
> +				continue;
> +			if (strncmp(pmc->m.mnt_fsname, normpath, nlen) != 0)
> +				continue;

You need to free normpath here before the "continue".

Also, when you normalize, why not go the extra mile of doing it all the
way as the patch I posted? I wanted to cover specs like
"host:/server/../home/./blah". This patch only does partial
normalization. The original patch also normalizes /proc/mount entry's
pathname (this avoids dealing with trailing '/' hack that exists now).

Re: [PATCH 1/1] umount.nfs: normalize path names during umounts.

[Malahal Naineni]

Malahal Naineni [malahal@us.ibm.com] wrote:
> >  		while (pmc->m.mnt_fsname[nlen - 1] == '/')
> >  			nlen--;
> > -		if (strncmp(pmc->m.mnt_fsname, mc->m.mnt_fsname, nlen) != 0)
> > -			continue;
> > +		/*
> > +		 * When the mtab and /proc/mounts are not the same
> > +		 * file, normalize the path in the mtab if needed.
> > +		 */
> > +		if (mtab_is_writable())
> > +			normpath = normalize_path(mc->m.mnt_fsname);
> > +
> > +		if (strncmp(pmc->m.mnt_fsname, mc->m.mnt_fsname, nlen) != 0) {
> > +			/* Is there a normalized path, if so compare that one too */
> > +			if (normpath == NULL)
> > +				continue;
> > +			if (strncmp(pmc->m.mnt_fsname, normpath, nlen) != 0)
> > +				continue;
> 
> You need to free normpath here before the "continue".

Better yet, you don't need to normalize the path inside the loop. The
path you normalize doesn't change, so keep it outside "do while" loop.

Regards, Malahal.

Re: [PATCH 1/1] umount.nfs: normalize path names during umounts.

[Steve Dickson]

On 03/05/2012 04:30 PM, Malahal Naineni wrote:
> Malahal Naineni [malahal@us.ibm.com] wrote:
>>>  		while (pmc->m.mnt_fsname[nlen - 1] == '/')
>>>  			nlen--;
>>> -		if (strncmp(pmc->m.mnt_fsname, mc->m.mnt_fsname, nlen) != 0)
>>> -			continue;
>>> +		/*
>>> +		 * When the mtab and /proc/mounts are not the same
>>> +		 * file, normalize the path in the mtab if needed.
>>> +		 */
>>> +		if (mtab_is_writable())
>>> +			normpath = normalize_path(mc->m.mnt_fsname);
>>> +
>>> +		if (strncmp(pmc->m.mnt_fsname, mc->m.mnt_fsname, nlen) != 0) {
>>> +			/* Is there a normalized path, if so compare that one too */
>>> +			if (normpath == NULL)
>>> +				continue;
>>> +			if (strncmp(pmc->m.mnt_fsname, normpath, nlen) != 0)
>>> +				continue;
>>
>> You need to free normpath here before the "continue".
> 
> Better yet, you don't need to normalize the path inside the loop. The
> path you normalize doesn't change, so keep it outside "do while" loop.
Your are right... thank you!

steved.

Re: [PATCH 1/1] umount.nfs: normalize path names during umounts.

[Steve Dickson]

On 03/05/2012 04:20 PM, Malahal Naineni wrote:
> Steve Dickson [steved@redhat.com] wrote:
>> So path names are found during umounts, normalize
>> path names by removing any extra slashes and add
>> a lead slash if one does not exist.
>>
>> This normalization only has to occur when the mtab
>> and /proc/mounts are not the same file.
>>
>> Signed-off-by: Steve Dickson <steved@redhat.com>
>> ---
>>  utils/mount/nfsumount.c |   64 +++++++++++++++++++++++++++++++++++++++++++++-
>>  1 files changed, 62 insertions(+), 2 deletions(-)
>>
>> diff --git a/utils/mount/nfsumount.c b/utils/mount/nfsumount.c
>> index 3538d88..0f77261 100644
>> --- a/utils/mount/nfsumount.c
>> +++ b/utils/mount/nfsumount.c
>> @@ -140,6 +140,52 @@ static int del_mtab(const char *spec, const char *node)
>>  }
>>
>>  /*
>> + * To ensure the path is found during unmounts, strip
>> + * off the multiple '/' or add a '/' if one does not exist.
>> + */
>> +static inline char *
>> +normalize_path(char *spec) 
>> +{
>> +	char *colen, *ptr, *str, *dev;
>> +
>> +	if ((colen = strchr(spec, ':')) == NULL)
>> +		return NULL;
>> +
>> +	if (*(colen + 1) != '/') {
>> +		dev = str = malloc(strlen(spec) + 2);
>> +		if (dev == NULL) 
>> +			return NULL;
>> +
>> +		ptr = spec;
>> +		while (ptr <= colen)
>> +			*(str++) = *(ptr++);
>> +		*str++='/';
>> +		while (*ptr)
>> +			*(str++) = *(ptr++);
>> +		*str='\0';
>> +
>> +		return dev;
>> +	}
>> +
>> +	if (strstr(spec, "//") != NULL) {
>> +		dev = strdup(spec);
>> +		if (dev == NULL)
>> +			return NULL;
>> +
>> +		colen = strchr(dev, ':');
>> +		ptr = (colen +1);
>> +		while (*ptr && *(ptr+1) == '/')
>> +			ptr++;
>> +		while (*ptr)
>> +			*(++colen) = *(ptr++);
>> +		*(colen+1) = '\0';
>> +
>> +		return dev;
>> +	} 
>> +	return NULL;
>> +}
>> +
>> +/*
>>   * Detect NFSv4 mounts.
>>   *
>>   * Consult /proc/mounts to determine if the mount point
>> @@ -154,6 +200,7 @@ static int nfs_umount_is_vers4(const struct mntentchn *mc)
>>  	struct mntentchn *pmc;
>>  	struct mount_options *options;
>>  	int retval;
>> +	char *normpath=NULL;
>>
>>  	retval = -1;
>>  	pmc = getprocmntdirbackward(mc->m.mnt_dir, NULL);
>> @@ -171,8 +218,20 @@ static int nfs_umount_is_vers4(const struct mntentchn *mc)
>>  		 */
>>  		while (pmc->m.mnt_fsname[nlen - 1] == '/')
>>  			nlen--;
>> -		if (strncmp(pmc->m.mnt_fsname, mc->m.mnt_fsname, nlen) != 0)
>> -			continue;
>> +		/*
>> +		 * When the mtab and /proc/mounts are not the same
>> +		 * file, normalize the path in the mtab if needed.
>> +		 */
>> +		if (mtab_is_writable())
>> +			normpath = normalize_path(mc->m.mnt_fsname);
>> +
>> +		if (strncmp(pmc->m.mnt_fsname, mc->m.mnt_fsname, nlen) != 0) {
>> +			/* Is there a normalized path, if so compare that one too */
>> +			if (normpath == NULL)
>> +				continue;
>> +			if (strncmp(pmc->m.mnt_fsname, normpath, nlen) != 0)
>> +				continue;
> 
> You need to free normpath here before the "continue".
> 
> Also, when you normalize, why not go the extra mile of doing it all the
> way as the patch I posted? I wanted to cover specs like
> "host:/server/../home/./blah". This patch only does partial
> normalization. The original patch also normalizes /proc/mount entry's
> pathname (this avoids dealing with trailing '/' hack that exists now).
I just do not see the need for that type of complexity... Maybe I'm
being a bit naive, but I see two problems here. One, v4 mounts 
with multiple slashes and two v4 mounts without any slashes... 

Now both of our patches do address those issues but mine only
addresses those issues and no, it does not go the "extra mile" 
of addressing '..' in path names, but does it need to? Is 
there really an use case where people export things with ".."
in the path? 

Sometimes going the just extra mile just brings more pain... 
for no reason... and believe me I'm no runner...  8-) 

steved.

Re: [PATCH 1/1] umount.nfs: normalize path names during umounts.

[Myklebust, Trond]

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Re: [PATCH 1/1] umount.nfs: normalize path names during umounts.

[Steve Dickson]

On 03/05/2012 07:31 PM, Myklebust, Trond wrote:
> On Mon, 2012-03-05 at 19:27 -0500, Steve Dickson wrote:
>>
>> On 03/05/2012 04:20 PM, Malahal Naineni wrote:
>>> Steve Dickson [steved@redhat.com] wrote:
>>>
>>> Also, when you normalize, why not go the extra mile of doing it all the
>>> way as the patch I posted? I wanted to cover specs like
>>> "host:/server/../home/./blah". This patch only does partial
>>> normalization. The original patch also normalizes /proc/mount entry's
>>> pathname (this avoids dealing with trailing '/' hack that exists now).
>> I just do not see the need for that type of complexity... Maybe I'm
>> being a bit naive, but I see two problems here. One, v4 mounts 
>> with multiple slashes and two v4 mounts without any slashes... 
>>
>> Now both of our patches do address those issues but mine only
>> addresses those issues and no, it does not go the "extra mile" 
>> of addressing '..' in path names, but does it need to? Is 
>> there really an use case where people export things with ".."
>> in the path? 
>>
>> Sometimes going the just extra mile just brings more pain... 
>> for no reason... and believe me I'm no runner...  8-) 
> 
> Note that the NFSv4 server may have symlinks and/or referrals in the
> mount path, in which case it is game over for this kind of approach
> anyway: you can't 'normalise' your way to interpreting that...
Well I guess we will cross that bridge when we get there... At
this point I just want fixes these two bugs and move on... 

> 
> Is there any reason why we actually care about checking the crap
> in /etc/mtab on umount?
> 
Yeah... its called backwards compatibility with older distros...
Believe, if I could bury mtab I would... in a New York minute! 
I just don't see it happening... 

steved.

Re: [PATCH 1/1] umount.nfs: normalize path names during umounts.

[Myklebust, Trond]

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Re: [PATCH 1/1] umount.nfs: normalize path names during umounts.

[Steve Dickson]

On 03/05/2012 08:04 PM, Myklebust, Trond wrote:
>>> Is there any reason why we actually care about checking the crap
>>> in /etc/mtab on umount?
>>>
>> Yeah... its called backwards compatibility with older distros...
>> Believe, if I could bury mtab I would... in a New York minute! 
>> I just don't see it happening... 
> 
> Yes, but despite all your work, you are just replacing one broken model
> by another.
>
> 
> At least with the current code, they can _see_ that the model is broken
> and have an immediate incentive to move to the
> mtab-is-a-symlink-to-/proc/mounts based model. The latter is in any case
> the only one that is valid in the mount-namespace based world in which
> we've been living for the past 5 years or so...
> 
I do not disagree with what you are saying... The fact the code/model
is broken is unarguably true... Relying on info in the mtab verses 
/proc/mounts is completely brain dead... But those bits are on the 
street and need to be fixed... So the question is how to fix
them...

Sending out a patch that symbolically links mtab to /proc/mounts
would solve this entire problem! But I just can't make major change
like that in established worlds... Who know what people use mtab
for... I certainly don't. Changing mtab to read-only is recipe for
disaster... IMHO... 

Now if we don't want to take a patch like this in upstream 
that's a different story... This patch is basically meaningless 
when  it comes to new Linux distros... I'm ok with that..
But I do think its wise for us to at least try to be somewhat
backwards compatible....

steved.
 

Re: [PATCH 1/1] umount.nfs: normalize path names during umounts.

[Jim Rees]

I don't understand the backward compatibility issue.  Are there times when
you have a mount, and it's in /etc/mtab, but not in /proc/mounts?  I don't
see how that's possible.

Re: [PATCH 1/1] umount.nfs: normalize path names during umounts.

[Malahal Naineni]

Jim Rees [rees@umich.edu] wrote:
> I don't understand the backward compatibility issue.  Are there times when
> you have a mount, and it's in /etc/mtab, but not in /proc/mounts?  I don't
> see how that's possible.

No, but that is what NFS umount thinks due to slight differences in
those two files. Happens only in NFSv4 world. 

Re: [PATCH 1/1] umount.nfs: normalize path names during umounts.

[Steve Dickson]

On 03/05/2012 09:25 PM, Malahal Naineni wrote:
> Jim Rees [rees@umich.edu] wrote:
>> I don't understand the backward compatibility issue.  Are there times when
>> you have a mount, and it's in /etc/mtab, but not in /proc/mounts?  I don't
>> see how that's possible.
> 
> No, but that is what NFS umount thinks due to slight differences in
> those two files. Happens only in NFSv4 world. 
Exactly... When /etc/mtab and /proc/mounts are not symbolically 
linked the v4 mount are written differently to both files as 
well as v3 mount are also written differently that v4 mounts...

steved.

Re: [PATCH 0/1] Normalized path names on umounts (take 2)

[Chuck Lever]

On Mar 5, 2012, at 2:36 PM, Steve Dickson wrote:

> There is a second attempted at making paths in the
> device names that have multiple slashes or no slash
> at all unmount-able, without breaking any APIs.
> 
> Due to the way entries are written to both the /etc/mtab
> and /proc/mounts, multiple slash have to be stripped and
> leading slash have to be added (when they don't exist) 
> on v4 mounts.

I thought a pathname without a leading slash was allowed for NFSv4, for mounting OSD devices?  Not really sure.

> With v3 mounts this normalization can 
> not occur since those entries are always in the same format.
> 
> Finally, this normalization only needs to happen
> when the mtab and /proc/mounts are not the same file.
> 
> Steve Dickson (1):
>  umount.nfs: normalize path names during umounts.
> 
> utils/mount/nfsumount.c |   64 +++++++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 62 insertions(+), 2 deletions(-)
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

-- 
Chuck Lever
chuck[dot]lever[at]oracle[dot]com

Re: [PATCH 0/1] Normalized path names on umounts (take 2)

[Steve Dickson]

On 03/05/2012 02:37 PM, Chuck Lever wrote:
> 
> On Mar 5, 2012, at 2:36 PM, Steve Dickson wrote:
> 
>> There is a second attempted at making paths in the
>> device names that have multiple slashes or no slash
>> at all unmount-able, without breaking any APIs.
>>
>> Due to the way entries are written to both the /etc/mtab
>> and /proc/mounts, multiple slash have to be stripped and
>> leading slash have to be added (when they don't exist) 
>> on v4 mounts.
> 
> I thought a pathname without a leading slash was allowed for NFSv4, for mounting OSD devices?  Not really sure.
Sorry I guess I didn't make myself clear... this adding and subtracting 
of slashes only happen on umounts and only if /etc/mtab is not symbolically
to /proc/mounts.  Has no effect on the mounts that do or do not have 
slashes... Is that a bit clearer? 

steved.

> 
>> With v3 mounts this normalization can 
>> not occur since those entries are always in the same format.
>>
>> Finally, this normalization only needs to happen
>> when the mtab and /proc/mounts are not the same file.
>>
>> Steve Dickson (1):
>>  umount.nfs: normalize path names during umounts.
>>
>> utils/mount/nfsumount.c |   64 +++++++++++++++++++++++++++++++++++++++++++++-
>> 1 files changed, 62 insertions(+), 2 deletions(-)
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>