[RFC PATCH 1/2] exportfs: pass export option flags to the kernel when testing export

[RFC PATCH 1/2] exportfs: pass export option flags to the kernel when testing export

[Jeff Layton]

test_export takes a flag that just says whether to pass in the fsid or
not. This means that all we can test is the NFSEXP_FSIDi flag.

Instead of doing that, pass in the actual export options that we
intend to use (sometimes or'ed with NFSEXP_FSID to test whether that
might be the reason for the failure).

This allows us to test the actual export options that we plan to use,
and can allow the kernel to vet them properly before mount time.

The rationale here is a patch that I have that will add the ability
for filesystems to opt out of subtree checking when they can't
properly support it.

Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
---
 utils/exportfs/exportfs.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/utils/exportfs/exportfs.c b/utils/exportfs/exportfs.c
index c7a79a69b5d6..cac01fc25f9a 100644
--- a/utils/exportfs/exportfs.c
+++ b/utils/exportfs/exportfs.c
@@ -531,7 +531,7 @@ static int can_test(void)
 	return 1;
 }
 
-static int test_export(char *path, int with_fsid)
+static int test_export(char *path, int opts)
 {
 	/* beside max path, buf size should take protocol str into account */
 	char buf[NFS_MAXPATHLEN+1+64] = { 0 };
@@ -545,7 +545,7 @@ static int test_export(char *path, int with_fsid)
 	qword_add(&bp, &len, path);
 	if (len < 1)
 		return 0;
-	snprintf(bp, len, " 3 %d 65534 65534 0\n", with_fsid ? NFSEXP_FSID : 0);
+	snprintf(bp, len, " 3 %d 65534 65534 0\n", opts);
 	fd = open("/proc/net/rpc/nfsd.export/channel", O_WRONLY);
 	if (fd < 0)
 		return 0;
@@ -587,12 +587,12 @@ validate_export(nfs_export *exp)
 
 	if ((exp->m_export.e_flags & NFSEXP_FSID) || exp->m_export.e_uuid ||
 	    fs_has_fsid) {
-		if ( !test_export(path, 1)) {
+		if ( !test_export(path, exp->m_export.e_flags)) {
 			xlog(L_ERROR, "%s does not support NFS export", path);
 			return;
 		}
-	} else if ( ! test_export(path, 0)) {
-		if (test_export(path, 1))
+	} else if ( ! test_export(path, exp->m_export.e_flags)) {
+		if (test_export(path, exp->m_export.e_flags & NFSEXP_FSID))
 			xlog(L_ERROR, "%s requires fsid= for NFS export", path);
 		else
 			xlog(L_ERROR, "%s does not support NFS export", path);
-- 
2.4.3

[RFC PATCH 2/2] exportfs: vet exports for subtree checking when testing the export fails

[Jeff Layton]

I have a proposed kernel patch that would allow filesystems (such as
NFS) to opt out of subtree checking when they are exported. We do want
to warn people at export time however if that doesn't work. If we issued
a test_export that fails and don't have NFSEXP_NOSUBTREECHECK already set
in it, then try it again with that set. If that works then we know that
the filesystem requires NFSEXP_NOSUBTREECHECK be set.

Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
---
 utils/exportfs/exportfs.c | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/utils/exportfs/exportfs.c b/utils/exportfs/exportfs.c
index cac01fc25f9a..1b704e85c024 100644
--- a/utils/exportfs/exportfs.c
+++ b/utils/exportfs/exportfs.c
@@ -557,6 +557,20 @@ static int test_export(char *path, int opts)
 }
 
 static void
+validate_subtree_check(nfs_export *exp)
+{
+	char *path = exp->m_export.e_path;
+
+	if (!(exp->m_export.e_flags & NFSEXP_NOSUBTREECHECK)) {
+		if (test_export(path, exp->m_export.e_flags | NFSEXP_NOSUBTREECHECK)) {
+			xlog(L_ERROR, "%s does not support subtree checking", path);
+			return;
+		}
+	}
+	xlog(L_ERROR, "%s does not support NFS export", path);
+}
+
+static void
 validate_export(nfs_export *exp)
 {
 	/* Check that the given export point is potentially exportable.
@@ -587,16 +601,13 @@ validate_export(nfs_export *exp)
 
 	if ((exp->m_export.e_flags & NFSEXP_FSID) || exp->m_export.e_uuid ||
 	    fs_has_fsid) {
-		if ( !test_export(path, exp->m_export.e_flags)) {
-			xlog(L_ERROR, "%s does not support NFS export", path);
-			return;
-		}
-	} else if ( ! test_export(path, exp->m_export.e_flags)) {
+		if (!test_export(path, exp->m_export.e_flags))
+			validate_subtree_check(exp);
+	} else if (!test_export(path, exp->m_export.e_flags)) {
 		if (test_export(path, exp->m_export.e_flags & NFSEXP_FSID))
 			xlog(L_ERROR, "%s requires fsid= for NFS export", path);
 		else
-			xlog(L_ERROR, "%s does not support NFS export", path);
-		return;
+			validate_subtree_check(exp);
 
 	}
 }
-- 
2.4.3

Re: [RFC PATCH 2/2] exportfs: vet exports for subtree checking when testing the export fails

[J. Bruce Fields]

On Wed, Nov 18, 2015 at 11:50:30AM -0500, Jeff Layton wrote:
> I have a proposed kernel patch that would allow filesystems (such as
> NFS) to opt out of subtree checking when they are exported. We do want
> to warn people at export time however if that doesn't work. If we issued
> a test_export that fails and don't have NFSEXP_NOSUBTREECHECK already set
> in it, then try it again with that set. If that works then we know that
> the filesystem requires NFSEXP_NOSUBTREECHECK be set.

Makes sense to me, ACK.--b.

> 
> Cc: Neil Brown <neilb@suse.de>
> Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
> ---
>  utils/exportfs/exportfs.c | 25 ++++++++++++++++++-------
>  1 file changed, 18 insertions(+), 7 deletions(-)
> 
> diff --git a/utils/exportfs/exportfs.c b/utils/exportfs/exportfs.c
> index cac01fc25f9a..1b704e85c024 100644
> --- a/utils/exportfs/exportfs.c
> +++ b/utils/exportfs/exportfs.c
> @@ -557,6 +557,20 @@ static int test_export(char *path, int opts)
>  }
>  
>  static void
> +validate_subtree_check(nfs_export *exp)
> +{
> +	char *path = exp->m_export.e_path;
> +
> +	if (!(exp->m_export.e_flags & NFSEXP_NOSUBTREECHECK)) {
> +		if (test_export(path, exp->m_export.e_flags | NFSEXP_NOSUBTREECHECK)) {
> +			xlog(L_ERROR, "%s does not support subtree checking", path);
> +			return;
> +		}
> +	}
> +	xlog(L_ERROR, "%s does not support NFS export", path);
> +}
> +
> +static void
>  validate_export(nfs_export *exp)
>  {
>  	/* Check that the given export point is potentially exportable.
> @@ -587,16 +601,13 @@ validate_export(nfs_export *exp)
>  
>  	if ((exp->m_export.e_flags & NFSEXP_FSID) || exp->m_export.e_uuid ||
>  	    fs_has_fsid) {
> -		if ( !test_export(path, exp->m_export.e_flags)) {
> -			xlog(L_ERROR, "%s does not support NFS export", path);
> -			return;
> -		}
> -	} else if ( ! test_export(path, exp->m_export.e_flags)) {
> +		if (!test_export(path, exp->m_export.e_flags))
> +			validate_subtree_check(exp);
> +	} else if (!test_export(path, exp->m_export.e_flags)) {
>  		if (test_export(path, exp->m_export.e_flags & NFSEXP_FSID))
>  			xlog(L_ERROR, "%s requires fsid= for NFS export", path);
>  		else
> -			xlog(L_ERROR, "%s does not support NFS export", path);
> -		return;
> +			validate_subtree_check(exp);
>  
>  	}
>  }
> -- 
> 2.4.3

Re: [RFC PATCH 1/2] exportfs: pass export option flags to the kernel when testing export

[Jeff Layton]

On Wed, 18 Nov 2015 11:50:29 -0500
Jeff Layton <jlayton@poochiereds.net> wrote:

> test_export takes a flag that just says whether to pass in the fsid or
> not. This means that all we can test is the NFSEXP_FSIDi flag.
> 
> Instead of doing that, pass in the actual export options that we
> intend to use (sometimes or'ed with NFSEXP_FSID to test whether that
> might be the reason for the failure).
> 
> This allows us to test the actual export options that we plan to use,
> and can allow the kernel to vet them properly before mount time.
> 
> The rationale here is a patch that I have that will add the ability
> for filesystems to opt out of subtree checking when they can't
> properly support it.
> 
> Cc: Neil Brown <neilb@suse.de>
> Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
> ---
>  utils/exportfs/exportfs.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/utils/exportfs/exportfs.c b/utils/exportfs/exportfs.c
> index c7a79a69b5d6..cac01fc25f9a 100644
> --- a/utils/exportfs/exportfs.c
> +++ b/utils/exportfs/exportfs.c
> @@ -531,7 +531,7 @@ static int can_test(void)
>  	return 1;
>  }
>  
> -static int test_export(char *path, int with_fsid)
> +static int test_export(char *path, int opts)
>  {
>  	/* beside max path, buf size should take protocol str into account */
>  	char buf[NFS_MAXPATHLEN+1+64] = { 0 };
> @@ -545,7 +545,7 @@ static int test_export(char *path, int with_fsid)
>  	qword_add(&bp, &len, path);
>  	if (len < 1)
>  		return 0;
> -	snprintf(bp, len, " 3 %d 65534 65534 0\n", with_fsid ? NFSEXP_FSID : 0);
> +	snprintf(bp, len, " 3 %d 65534 65534 0\n", opts);
>  	fd = open("/proc/net/rpc/nfsd.export/channel", O_WRONLY);
>  	if (fd < 0)
>  		return 0;
> @@ -587,12 +587,12 @@ validate_export(nfs_export *exp)
>  
>  	if ((exp->m_export.e_flags & NFSEXP_FSID) || exp->m_export.e_uuid ||
>  	    fs_has_fsid) {
> -		if ( !test_export(path, 1)) {
> +		if ( !test_export(path, exp->m_export.e_flags)) {
>  			xlog(L_ERROR, "%s does not support NFS export", path);
>  			return;
>  		}
> -	} else if ( ! test_export(path, 0)) {
> -		if (test_export(path, 1))
> +	} else if ( ! test_export(path, exp->m_export.e_flags)) {
> +		if (test_export(path, exp->m_export.e_flags & NFSEXP_FSID))

Duh, that should of course be "exp->m_export.e_flags | NFSEXP_FSID".
I'll plan to resend after I wait a bit for others to comment. Please
don't merge this as-is though -- it obviously needs better testing.

We might be able to simplify the above logic a little too...hmmm...

>  			xlog(L_ERROR, "%s requires fsid= for NFS export", path);
>  		else
>  			xlog(L_ERROR, "%s does not support NFS export", path);


-- 
Jeff Layton <jlayton@poochiereds.net>

Re: [RFC PATCH 1/2] exportfs: pass export option flags to the kernel when testing export

[Steve Dickson]

On 11/18/2015 02:16 PM, Jeff Layton wrote:
> On Wed, 18 Nov 2015 11:50:29 -0500
> Jeff Layton <jlayton@poochiereds.net> wrote:
> 
>> test_export takes a flag that just says whether to pass in the fsid or
>> not. This means that all we can test is the NFSEXP_FSIDi flag.
>>
>> Instead of doing that, pass in the actual export options that we
>> intend to use (sometimes or'ed with NFSEXP_FSID to test whether that
>> might be the reason for the failure).
>>
>> This allows us to test the actual export options that we plan to use,
>> and can allow the kernel to vet them properly before mount time.
>>
>> The rationale here is a patch that I have that will add the ability
>> for filesystems to opt out of subtree checking when they can't
>> properly support it.
>>
>> Cc: Neil Brown <neilb@suse.de>
>> Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
>> ---
>>  utils/exportfs/exportfs.c | 10 +++++-----
>>  1 file changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/utils/exportfs/exportfs.c b/utils/exportfs/exportfs.c
>> index c7a79a69b5d6..cac01fc25f9a 100644
>> --- a/utils/exportfs/exportfs.c
>> +++ b/utils/exportfs/exportfs.c
>> @@ -531,7 +531,7 @@ static int can_test(void)
>>  	return 1;
>>  }
>>  
>> -static int test_export(char *path, int with_fsid)
>> +static int test_export(char *path, int opts)
>>  {
>>  	/* beside max path, buf size should take protocol str into account */
>>  	char buf[NFS_MAXPATHLEN+1+64] = { 0 };
>> @@ -545,7 +545,7 @@ static int test_export(char *path, int with_fsid)
>>  	qword_add(&bp, &len, path);
>>  	if (len < 1)
>>  		return 0;
>> -	snprintf(bp, len, " 3 %d 65534 65534 0\n", with_fsid ? NFSEXP_FSID : 0);
>> +	snprintf(bp, len, " 3 %d 65534 65534 0\n", opts);
>>  	fd = open("/proc/net/rpc/nfsd.export/channel", O_WRONLY);
>>  	if (fd < 0)
>>  		return 0;
>> @@ -587,12 +587,12 @@ validate_export(nfs_export *exp)
>>  
>>  	if ((exp->m_export.e_flags & NFSEXP_FSID) || exp->m_export.e_uuid ||
>>  	    fs_has_fsid) {
>> -		if ( !test_export(path, 1)) {
>> +		if ( !test_export(path, exp->m_export.e_flags)) {
>>  			xlog(L_ERROR, "%s does not support NFS export", path);
>>  			return;
>>  		}
>> -	} else if ( ! test_export(path, 0)) {
>> -		if (test_export(path, 1))
>> +	} else if ( ! test_export(path, exp->m_export.e_flags)) {
>> +		if (test_export(path, exp->m_export.e_flags & NFSEXP_FSID))
> 
> Duh, that should of course be "exp->m_export.e_flags | NFSEXP_FSID".
> I'll plan to resend after I wait a bit for others to comment. Please
> don't merge this as-is though -- it obviously needs better testing.
> 
> We might be able to simplify the above logic a little too...hmmm...
That logic did look a bit odd... I'll wait for the next version....

steved.

> 
>>  			xlog(L_ERROR, "%s requires fsid= for NFS export", path);
>>  		else
>>  			xlog(L_ERROR, "%s does not support NFS export", path);
> 
>