[PATCH] Fixed getdevinfo() and dlm_ino_hash() to search for the correct disk name.

[PATCH] Fixed getdevinfo() and dlm_ino_hash() to search for the correct disk name.

[J. Bruce Fields]

The patch "pnfsd: fix test in nfsd4_find_pnfs_dlm_device" was obviously
correct; before that patch, nfsd4_find_pnfs_dlm_device() returned the
first device which did *not* match, instead of the first device which
did.

Other callers previous worked because they passed int the incorrect
name, and because we never had more than one element in the list, so
returning the first non-match would return the right thing.

But now we need to fix those callers.

From: Eric Anderle <eanderle@umich.edu>

---
 fs/nfsd/nfs4pnfsdlm.c |   12 +++++++++---
 1 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/fs/nfsd/nfs4pnfsdlm.c b/fs/nfsd/nfs4pnfsdlm.c
index 84caa6e..5a66a71 100644
--- a/fs/nfsd/nfs4pnfsdlm.c
+++ b/fs/nfsd/nfs4pnfsdlm.c
@@ -268,10 +268,13 @@ static int nfsd4_pnfs_dlm_getdevinfo(struct super_block *sb,
 	/*
 	 * If the DS list has not been established, return -EINVAL
 	 */
-	dlm_pdev = nfsd4_find_pnfs_dlm_device(sb->s_bdev->bd_disk->disk_name);
+	/* Long enough to hold "/dev/" + disk name */
+	char full_disk_name[6 + strlen(sb->s_bdev->bd_disk->disk_name)];
+	sprintf(full_disk_name, "/dev/%s", sb->s_bdev->bd_disk->disk_name);
+	dlm_pdev = nfsd4_find_pnfs_dlm_device(full_disk_name);
 	if (!dlm_pdev) {
 		dprintk("%s: DEBUG: disk %s Not Found\n", __func__,
-			sb->s_bdev->bd_disk->disk_name);
+			full_disk_name);
 		return err;
 	}
 
@@ -364,7 +367,10 @@ static int dlm_ino_hash(struct inode *ino)
 	/* If can't find the inode block device in the pnfs_dlm_deivce list
 	 * then don't hand out a layout
 	 */
-	de = nfsd4_find_pnfs_dlm_device(ino->i_sb->s_bdev->bd_disk->disk_name);
+	/* Long enough to hold "/dev/" + disk name */
+	char full_disk_name[6 + strlen(ino->i_sb->s_bdev->bd_disk->disk_name)];
+	sprintf(full_disk_name, "/dev/%s", ino->i_sb->s_bdev->bd_disk->disk_name);
+	de = nfsd4_find_pnfs_dlm_device(full_disk_name);
 	if (!de)
 		return -1;
 	hash_mask = de->num_ds - 1;
-- 
1.7.0.4

Re: [PATCH] Fixed getdevinfo() and dlm_ino_hash() to search for the correct disk name.

[J. Bruce Fields]

On Thu, Jun 10, 2010 at 09:33:37AM -0400, bfields wrote:
> The patch "pnfsd: fix test in nfsd4_find_pnfs_dlm_device" was obviously
> correct; before that patch, nfsd4_find_pnfs_dlm_device() returned the
> first device which did *not* match, instead of the first device which
> did.
> 
> Other callers previous worked because they passed int the incorrect
> name, and because we never had more than one element in the list, so
> returning the first non-match would return the right thing.

But then I don't know what point the "/dev/" is serving here.  May as
well just change the interface so that what's passed in is just the name
("sdc2" or whatever)--no use pretending this is some kind of path name
if it's not really.

However, I don't know whether passing in the disk name is really a
sensible way to refer to a filesystem in a user<->kernel api.

--b.

> 
> But now we need to fix those callers.
> 
> From: Eric Anderle <eanderle@umich.edu>
> 
> ---
>  fs/nfsd/nfs4pnfsdlm.c |   12 +++++++++---
>  1 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/nfsd/nfs4pnfsdlm.c b/fs/nfsd/nfs4pnfsdlm.c
> index 84caa6e..5a66a71 100644
> --- a/fs/nfsd/nfs4pnfsdlm.c
> +++ b/fs/nfsd/nfs4pnfsdlm.c
> @@ -268,10 +268,13 @@ static int nfsd4_pnfs_dlm_getdevinfo(struct super_block *sb,
>  	/*
>  	 * If the DS list has not been established, return -EINVAL
>  	 */
> -	dlm_pdev = nfsd4_find_pnfs_dlm_device(sb->s_bdev->bd_disk->disk_name);
> +	/* Long enough to hold "/dev/" + disk name */
> +	char full_disk_name[6 + strlen(sb->s_bdev->bd_disk->disk_name)];
> +	sprintf(full_disk_name, "/dev/%s", sb->s_bdev->bd_disk->disk_name);
> +	dlm_pdev = nfsd4_find_pnfs_dlm_device(full_disk_name);
>  	if (!dlm_pdev) {
>  		dprintk("%s: DEBUG: disk %s Not Found\n", __func__,
> -			sb->s_bdev->bd_disk->disk_name);
> +			full_disk_name);
>  		return err;
>  	}
>  
> @@ -364,7 +367,10 @@ static int dlm_ino_hash(struct inode *ino)
>  	/* If can't find the inode block device in the pnfs_dlm_deivce list
>  	 * then don't hand out a layout
>  	 */
> -	de = nfsd4_find_pnfs_dlm_device(ino->i_sb->s_bdev->bd_disk->disk_name);
> +	/* Long enough to hold "/dev/" + disk name */
> +	char full_disk_name[6 + strlen(ino->i_sb->s_bdev->bd_disk->disk_name)];
> +	sprintf(full_disk_name, "/dev/%s", ino->i_sb->s_bdev->bd_disk->disk_name);
> +	de = nfsd4_find_pnfs_dlm_device(full_disk_name);
>  	if (!de)
>  		return -1;
>  	hash_mask = de->num_ds - 1;
> -- 
> 1.7.0.4
> 

Re: [PATCH] Fixed getdevinfo() and dlm_ino_hash() to search for the correct disk name.

[Benny Halevy]

On Jun. 10, 2010, 16:35 +0300, "J. Bruce Fields" <bfields@fieldses.org> wrote:
> On Thu, Jun 10, 2010 at 09:33:37AM -0400, bfields wrote:
>> The patch "pnfsd: fix test in nfsd4_find_pnfs_dlm_device" was obviously
>> correct; before that patch, nfsd4_find_pnfs_dlm_device() returned the
>> first device which did *not* match, instead of the first device which
>> did.
>>
>> Other callers previous worked because they passed int the incorrect
>> name, and because we never had more than one element in the list, so
>> returning the first non-match would return the right thing.
> 
> But then I don't know what point the "/dev/" is serving here.  May as
> well just change the interface so that what's passed in is just the name
> ("sdc2" or whatever)--no use pretending this is some kind of path name
> if it's not really.
> 
> However, I don't know whether passing in the disk name is really a
> sensible way to refer to a filesystem in a user<->kernel api.
> 

up to you...  I think the whole scheme is currently GFS2 specific
and it assumes the device exists symmetrically on /dev/... on all
DSs.  The /dev prefix seems to be completely redundant.
It makes more sense to get rid of it in the user->kernel
API as passed down to nfsd4_set_pnfs_dlm_device() rather than
adding it here.

Benny

> --b.
> 
>>
>> But now we need to fix those callers.
>>
>> From: Eric Anderle <eanderle@umich.edu>
>>
>> ---
>>  fs/nfsd/nfs4pnfsdlm.c |   12 +++++++++---
>>  1 files changed, 9 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/nfsd/nfs4pnfsdlm.c b/fs/nfsd/nfs4pnfsdlm.c
>> index 84caa6e..5a66a71 100644
>> --- a/fs/nfsd/nfs4pnfsdlm.c
>> +++ b/fs/nfsd/nfs4pnfsdlm.c
>> @@ -268,10 +268,13 @@ static int nfsd4_pnfs_dlm_getdevinfo(struct super_block *sb,
>>  	/*
>>  	 * If the DS list has not been established, return -EINVAL
>>  	 */
>> -	dlm_pdev = nfsd4_find_pnfs_dlm_device(sb->s_bdev->bd_disk->disk_name);
>> +	/* Long enough to hold "/dev/" + disk name */
>> +	char full_disk_name[6 + strlen(sb->s_bdev->bd_disk->disk_name)];
>> +	sprintf(full_disk_name, "/dev/%s", sb->s_bdev->bd_disk->disk_name);
>> +	dlm_pdev = nfsd4_find_pnfs_dlm_device(full_disk_name);
>>  	if (!dlm_pdev) {
>>  		dprintk("%s: DEBUG: disk %s Not Found\n", __func__,
>> -			sb->s_bdev->bd_disk->disk_name);
>> +			full_disk_name);
>>  		return err;
>>  	}
>>  
>> @@ -364,7 +367,10 @@ static int dlm_ino_hash(struct inode *ino)
>>  	/* If can't find the inode block device in the pnfs_dlm_deivce list
>>  	 * then don't hand out a layout
>>  	 */
>> -	de = nfsd4_find_pnfs_dlm_device(ino->i_sb->s_bdev->bd_disk->disk_name);
>> +	/* Long enough to hold "/dev/" + disk name */
>> +	char full_disk_name[6 + strlen(ino->i_sb->s_bdev->bd_disk->disk_name)];
>> +	sprintf(full_disk_name, "/dev/%s", ino->i_sb->s_bdev->bd_disk->disk_name);
>> +	de = nfsd4_find_pnfs_dlm_device(full_disk_name);
>>  	if (!de)
>>  		return -1;
>>  	hash_mask = de->num_ds - 1;
>> -- 
>> 1.7.0.4
>>

Re: [PATCH] Fixed getdevinfo() and dlm_ino_hash() to search for the correct disk name.

[Benny Halevy]

On Jun. 10, 2010, 17:06 +0300, Benny Halevy <bhalevy@panasas.com> wrote:
> On Jun. 10, 2010, 16:35 +0300, "J. Bruce Fields" <bfields@fieldses.org> wrote:
>> On Thu, Jun 10, 2010 at 09:33:37AM -0400, bfields wrote:
>>> The patch "pnfsd: fix test in nfsd4_find_pnfs_dlm_device" was obviously
>>> correct; before that patch, nfsd4_find_pnfs_dlm_device() returned the
>>> first device which did *not* match, instead of the first device which
>>> did.
>>>
>>> Other callers previous worked because they passed int the incorrect
>>> name, and because we never had more than one element in the list, so
>>> returning the first non-match would return the right thing.
>>
>> But then I don't know what point the "/dev/" is serving here.  May as
>> well just change the interface so that what's passed in is just the name
>> ("sdc2" or whatever)--no use pretending this is some kind of path name
>> if it's not really.
>>
>> However, I don't know whether passing in the disk name is really a
>> sensible way to refer to a filesystem in a user<->kernel api.
>>
> 
> up to you...  I think the whole scheme is currently GFS2 specific
> and it assumes the device exists symmetrically on /dev/... on all
> DSs.  The /dev prefix seems to be completely redundant.
> It makes more sense to get rid of it in the user->kernel
> API as passed down to nfsd4_set_pnfs_dlm_device() rather than
> adding it here.

A more through design could use the fs uuid rather than the device name
which is kinda volatile...

Benny

> 
> Benny
> 
>> --b.
>>
>>>
>>> But now we need to fix those callers.
>>>
>>> From: Eric Anderle <eanderle@umich.edu>
>>>
>>> ---
>>>  fs/nfsd/nfs4pnfsdlm.c |   12 +++++++++---
>>>  1 files changed, 9 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/fs/nfsd/nfs4pnfsdlm.c b/fs/nfsd/nfs4pnfsdlm.c
>>> index 84caa6e..5a66a71 100644
>>> --- a/fs/nfsd/nfs4pnfsdlm.c
>>> +++ b/fs/nfsd/nfs4pnfsdlm.c
>>> @@ -268,10 +268,13 @@ static int nfsd4_pnfs_dlm_getdevinfo(struct super_block *sb,
>>>  	/*
>>>  	 * If the DS list has not been established, return -EINVAL
>>>  	 */
>>> -	dlm_pdev = nfsd4_find_pnfs_dlm_device(sb->s_bdev->bd_disk->disk_name);
>>> +	/* Long enough to hold "/dev/" + disk name */
>>> +	char full_disk_name[6 + strlen(sb->s_bdev->bd_disk->disk_name)];
>>> +	sprintf(full_disk_name, "/dev/%s", sb->s_bdev->bd_disk->disk_name);
>>> +	dlm_pdev = nfsd4_find_pnfs_dlm_device(full_disk_name);
>>>  	if (!dlm_pdev) {
>>>  		dprintk("%s: DEBUG: disk %s Not Found\n", __func__,
>>> -			sb->s_bdev->bd_disk->disk_name);
>>> +			full_disk_name);
>>>  		return err;
>>>  	}
>>>  
>>> @@ -364,7 +367,10 @@ static int dlm_ino_hash(struct inode *ino)
>>>  	/* If can't find the inode block device in the pnfs_dlm_deivce list
>>>  	 * then don't hand out a layout
>>>  	 */
>>> -	de = nfsd4_find_pnfs_dlm_device(ino->i_sb->s_bdev->bd_disk->disk_name);
>>> +	/* Long enough to hold "/dev/" + disk name */
>>> +	char full_disk_name[6 + strlen(ino->i_sb->s_bdev->bd_disk->disk_name)];
>>> +	sprintf(full_disk_name, "/dev/%s", ino->i_sb->s_bdev->bd_disk->disk_name);
>>> +	de = nfsd4_find_pnfs_dlm_device(full_disk_name);
>>>  	if (!de)
>>>  		return -1;
>>>  	hash_mask = de->num_ds - 1;
>>> -- 
>>> 1.7.0.4
>>>
> --
> 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

Re: [PATCH] Fixed getdevinfo() and dlm_ino_hash() to search for the correct disk name.

[Andy Adamson]

On Jun 10, 2010, at 10:06 AM, Benny Halevy wrote:

> On Jun. 10, 2010, 16:35 +0300, "J. Bruce Fields"  
> <bfields@fieldses.org> wrote:
>> On Thu, Jun 10, 2010 at 09:33:37AM -0400, bfields wrote:
>>> The patch "pnfsd: fix test in nfsd4_find_pnfs_dlm_device" was  
>>> obviously
>>> correct; before that patch, nfsd4_find_pnfs_dlm_device() returned  
>>> the
>>> first device which did *not* match, instead of the first device  
>>> which
>>> did.
>>>
>>> Other callers previous worked because they passed int the incorrect
>>> name, and because we never had more than one element in the list, so
>>> returning the first non-match would return the right thing.
>>
>> But then I don't know what point the "/dev/" is serving here.  May as
>> well just change the interface so that what's passed in is just the  
>> name
>> ("sdc2" or whatever)--no use pretending this is some kind of path  
>> name
>> if it's not really.
>>
>> However, I don't know whether passing in the disk name is really a
>> sensible way to refer to a filesystem in a user<->kernel api.
>>
>
> up to you...  I think the whole scheme is currently GFS2 specific

No, it's DLM specific, with GFS2 being the only current user.

> and it assumes the device exists symmetrically on /dev/... on all
> DSs.

No. This identifies the MDS exported DLM pNFS file system, and has  
nothing to do with the local DS file system.

>

> The /dev prefix seems to be completely redundant.
> It makes more sense to get rid of it in the user->kernel
> API as passed down to nfsd4_set_pnfs_dlm_device() rather than
> adding it here.

Sure.

>
> Benny
>
>> --b.
>>
>>>
>>> But now we need to fix those callers.
>>>
>>> From: Eric Anderle <eanderle@umich.edu>
>>>
>>> ---
>>> fs/nfsd/nfs4pnfsdlm.c |   12 +++++++++---
>>> 1 files changed, 9 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/fs/nfsd/nfs4pnfsdlm.c b/fs/nfsd/nfs4pnfsdlm.c
>>> index 84caa6e..5a66a71 100644
>>> --- a/fs/nfsd/nfs4pnfsdlm.c
>>> +++ b/fs/nfsd/nfs4pnfsdlm.c
>>> @@ -268,10 +268,13 @@ static int nfsd4_pnfs_dlm_getdevinfo(struct  
>>> super_block *sb,
>>> 	/*
>>> 	 * If the DS list has not been established, return -EINVAL
>>> 	 */
>>> -	dlm_pdev = nfsd4_find_pnfs_dlm_device(sb->s_bdev->bd_disk- 
>>> >disk_name);
>>> +	/* Long enough to hold "/dev/" + disk name */
>>> +	char full_disk_name[6 + strlen(sb->s_bdev->bd_disk->disk_name)];
>>> +	sprintf(full_disk_name, "/dev/%s", sb->s_bdev->bd_disk- 
>>> >disk_name);
>>> +	dlm_pdev = nfsd4_find_pnfs_dlm_device(full_disk_name);
>>> 	if (!dlm_pdev) {
>>> 		dprintk("%s: DEBUG: disk %s Not Found\n", __func__,
>>> -			sb->s_bdev->bd_disk->disk_name);
>>> +			full_disk_name);
>>> 		return err;
>>> 	}
>>>
>>> @@ -364,7 +367,10 @@ static int dlm_ino_hash(struct inode *ino)
>>> 	/* If can't find the inode block device in the pnfs_dlm_deivce list
>>> 	 * then don't hand out a layout
>>> 	 */
>>> -	de = nfsd4_find_pnfs_dlm_device(ino->i_sb->s_bdev->bd_disk- 
>>> >disk_name);
>>> +	/* Long enough to hold "/dev/" + disk name */
>>> +	char full_disk_name[6 + strlen(ino->i_sb->s_bdev->bd_disk- 
>>> >disk_name)];
>>> +	sprintf(full_disk_name, "/dev/%s", ino->i_sb->s_bdev->bd_disk- 
>>> >disk_name);
>>> +	de = nfsd4_find_pnfs_dlm_device(full_disk_name);
>>> 	if (!de)
>>> 		return -1;
>>> 	hash_mask = de->num_ds - 1;
>>> -- 
>>> 1.7.0.4
>>>
> --
> 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

Re: [PATCH] Fixed getdevinfo() and dlm_ino_hash() to search for the correct disk name.

[Eric Anderle]

What if we added a struct block_device member to dlm_device_list? That
way we could look it up by major:minor numbers.

On Thu, 2010-06-10 at 10:36 -0400, Andy Adamson wrote:
> On Jun 10, 2010, at 10:06 AM, Benny Halevy wrote:
> 
> > On Jun. 10, 2010, 16:35 +0300, "J. Bruce Fields"  
> > <bfields@fieldses.org> wrote:
> >> On Thu, Jun 10, 2010 at 09:33:37AM -0400, bfields wrote:
> >>> The patch "pnfsd: fix test in nfsd4_find_pnfs_dlm_device" was  
> >>> obviously
> >>> correct; before that patch, nfsd4_find_pnfs_dlm_device() returned  
> >>> the
> >>> first device which did *not* match, instead of the first device  
> >>> which
> >>> did.
> >>>
> >>> Other callers previous worked because they passed int the incorrect
> >>> name, and because we never had more than one element in the list, so
> >>> returning the first non-match would return the right thing.
> >>
> >> But then I don't know what point the "/dev/" is serving here.  May as
> >> well just change the interface so that what's passed in is just the  
> >> name
> >> ("sdc2" or whatever)--no use pretending this is some kind of path  
> >> name
> >> if it's not really.
> >>
> >> However, I don't know whether passing in the disk name is really a
> >> sensible way to refer to a filesystem in a user<->kernel api.
> >>
> >
> > up to you...  I think the whole scheme is currently GFS2 specific
> 
> No, it's DLM specific, with GFS2 being the only current user.
> 
> > and it assumes the device exists symmetrically on /dev/... on all
> > DSs.
> 
> No. This identifies the MDS exported DLM pNFS file system, and has  
> nothing to do with the local DS file system.
> 
> >
> 
> > The /dev prefix seems to be completely redundant.
> > It makes more sense to get rid of it in the user->kernel
> > API as passed down to nfsd4_set_pnfs_dlm_device() rather than
> > adding it here.
> 
> Sure.
> 
> >
> > Benny
> >
> >> --b.
> >>
> >>>
> >>> But now we need to fix those callers.
> >>>
> >>> From: Eric Anderle <eanderle@umich.edu>
> >>>
> >>> ---
> >>> fs/nfsd/nfs4pnfsdlm.c |   12 +++++++++---
> >>> 1 files changed, 9 insertions(+), 3 deletions(-)
> >>>
> >>> diff --git a/fs/nfsd/nfs4pnfsdlm.c b/fs/nfsd/nfs4pnfsdlm.c
> >>> index 84caa6e..5a66a71 100644
> >>> --- a/fs/nfsd/nfs4pnfsdlm.c
> >>> +++ b/fs/nfsd/nfs4pnfsdlm.c
> >>> @@ -268,10 +268,13 @@ static int nfsd4_pnfs_dlm_getdevinfo(struct  
> >>> super_block *sb,
> >>> 	/*
> >>> 	 * If the DS list has not been established, return -EINVAL
> >>> 	 */
> >>> -	dlm_pdev = nfsd4_find_pnfs_dlm_device(sb->s_bdev->bd_disk- 
> >>> >disk_name);
> >>> +	/* Long enough to hold "/dev/" + disk name */
> >>> +	char full_disk_name[6 + strlen(sb->s_bdev->bd_disk->disk_name)];
> >>> +	sprintf(full_disk_name, "/dev/%s", sb->s_bdev->bd_disk- 
> >>> >disk_name);
> >>> +	dlm_pdev = nfsd4_find_pnfs_dlm_device(full_disk_name);
> >>> 	if (!dlm_pdev) {
> >>> 		dprintk("%s: DEBUG: disk %s Not Found\n", __func__,
> >>> -			sb->s_bdev->bd_disk->disk_name);
> >>> +			full_disk_name);
> >>> 		return err;
> >>> 	}
> >>>
> >>> @@ -364,7 +367,10 @@ static int dlm_ino_hash(struct inode *ino)
> >>> 	/* If can't find the inode block device in the pnfs_dlm_deivce list
> >>> 	 * then don't hand out a layout
> >>> 	 */
> >>> -	de = nfsd4_find_pnfs_dlm_device(ino->i_sb->s_bdev->bd_disk- 
> >>> >disk_name);
> >>> +	/* Long enough to hold "/dev/" + disk name */
> >>> +	char full_disk_name[6 + strlen(ino->i_sb->s_bdev->bd_disk- 
> >>> >disk_name)];
> >>> +	sprintf(full_disk_name, "/dev/%s", ino->i_sb->s_bdev->bd_disk- 
> >>> >disk_name);
> >>> +	de = nfsd4_find_pnfs_dlm_device(full_disk_name);
> >>> 	if (!de)
> >>> 		return -1;
> >>> 	hash_mask = de->num_ds - 1;
> >>> -- 
> >>> 1.7.0.4
> >>>
> > --
> > 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
> 
> 
> 

-- 
Eric Anderle <eanderle@umich.edu>
U-M Class of 2013

Re: [PATCH] Fixed getdevinfo() and dlm_ino_hash() to search for the correct disk name.

[J. Bruce Fields]

On Thu, Jun 10, 2010 at 10:52:52AM -0400, Eric Anderle wrote:
> What if we added a struct block_device member to dlm_device_list? That
> way we could look it up by major:minor numbers.

I don't know.

By the way:

> > >>> diff --git a/fs/nfsd/nfs4pnfsdlm.c b/fs/nfsd/nfs4pnfsdlm.c
> > >>> index 84caa6e..5a66a71 100644
> > >>> --- a/fs/nfsd/nfs4pnfsdlm.c
> > >>> +++ b/fs/nfsd/nfs4pnfsdlm.c
> > >>> @@ -268,10 +268,13 @@ static int nfsd4_pnfs_dlm_getdevinfo(struct  
> > >>> super_block *sb,
> > >>> 	/*
> > >>> 	 * If the DS list has not been established, return -EINVAL
> > >>> 	 */
> > >>> -	dlm_pdev = nfsd4_find_pnfs_dlm_device(sb->s_bdev->bd_disk- 
> > >>> >disk_name);
> > >>> +	/* Long enough to hold "/dev/" + disk name */
> > >>> +	char full_disk_name[6 + strlen(sb->s_bdev->bd_disk->disk_name)];
> > >>> +	sprintf(full_disk_name, "/dev/%s", sb->s_bdev->bd_disk- 
> > >>> >disk_name);
> > >>> +	dlm_pdev = nfsd4_find_pnfs_dlm_device(full_disk_name);
> > >>> 	if (!dlm_pdev) {
> > >>> 		dprintk("%s: DEBUG: disk %s Not Found\n", __func__,
> > >>> -			sb->s_bdev->bd_disk->disk_name);
> > >>> +			full_disk_name);
> > >>> 		return err;
> > >>> 	}
> > >>>
> > >>> @@ -364,7 +367,10 @@ static int dlm_ino_hash(struct inode *ino)
> > >>> 	/* If can't find the inode block device in the pnfs_dlm_deivce list
> > >>> 	 * then don't hand out a layout
> > >>> 	 */
> > >>> -	de = nfsd4_find_pnfs_dlm_device(ino->i_sb->s_bdev->bd_disk- 
> > >>> >disk_name);
> > >>> +	/* Long enough to hold "/dev/" + disk name */
> > >>> +	char full_disk_name[6 + strlen(ino->i_sb->s_bdev->bd_disk- 
> > >>> >disk_name)];
> > >>> +	sprintf(full_disk_name, "/dev/%s", ino->i_sb->s_bdev->bd_disk- 
> > >>> >disk_name);
> > >>> +	de = nfsd4_find_pnfs_dlm_device(full_disk_name);
> > >>> 	if (!de)
> > >>> 		return -1;
> > >>> 	hash_mask = de->num_ds - 1;

There's some duplicated code there; it should probably go into a common
function called from both places.

--b.