[fedfs-utils] [PATCH] NFSD: Change name of extended attribute containing junction

[Chuck Lever]

On Dec 19, 2011, at 4:52 PM, J. Bruce Fields wrote:

> On Mon, Dec 19, 2011 at 02:38:43PM -0500, Chuck Lever wrote:
>> As of fedfs-utils-0.8.0, user space stores all NFS junction
>> information in a single extended attribute: "trusted.junction.nfs".
> 
> I suspect the break of backwards-compatibility is fine, but we should
> add a note explaining it; would something like this be right?:
> 
> 	This breaks compatibility with fedfs-utils versions before
> 	0.8.0.  As fedfs-utils has not been widely distributed, we don't
> 	believe this will affect anyone.

More strongly: fedfs-utils is an alpha quality code release.  We don't guarantee any backwards compatibility.

> (Cc'ing jlayton: does this cause a problem for whatever just went into
> Fedora?)
> 
> --b.
> 
>> 
>> Both FedFS and NFS basic junctions are stored in this one attribute,
>> and the intention is that all future forms of NFS junction metadata
>> will be stored in this attribute.  Other protocols may use a different
>> extended attribute.
>> 
>> Thus NFSD needs to look only for that one extended attribute.  The
>> "trusted.junction.type" xattr is deprecated.
>> 
>> Signed-off-by: Chuck Lever <chuck.lever at oracle.com>
>> ---
>> 
>> fs/nfsd/vfs.c |   17 ++++++++++++++---
>> 1 files changed, 14 insertions(+), 3 deletions(-)
>> 
>> diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
>> index d1d4d5e..b494f86 100644
>> --- a/fs/nfsd/vfs.c
>> +++ b/fs/nfsd/vfs.c
>> @@ -594,8 +594,19 @@ nfsd4_get_nfs4_acl(struct svc_rqst *rqstp, struct dentry *dentry, struct nfs4_ac
>> 	return error;
>> }
>> 
>> -#define NFSD_XATTR_JUNCTION_PREFIX XATTR_TRUSTED_PREFIX "junction."
>> -#define NFSD_XATTR_JUNCTION_TYPE NFSD_XATTR_JUNCTION_PREFIX "type"
>> +/*
>> + * NFS junction information is stored in an extended attribute.
>> + */
>> +#define NFSD_JUNCTION_XATTR_NAME	XATTR_TRUSTED_PREFIX "junction.nfs"
>> +
>> +/**
>> + * nfsd4_is_junction - Test if an object could be an NFS junction
>> + *
>> + * @dentry: object to test
>> + *
>> + * Returns 1 if "dentry" appears to contain NFS junction information.
>> + * Otherwise 0 is returned.
>> + */
>> int nfsd4_is_junction(struct dentry *dentry)
>> {
>> 	struct inode *inode = dentry->d_inode;
>> @@ -606,7 +617,7 @@ int nfsd4_is_junction(struct dentry *dentry)
>> 		return 0;
>> 	if (!(inode->i_mode & S_ISVTX))
>> 		return 0;
>> -	if (vfs_getxattr(dentry, NFSD_XATTR_JUNCTION_TYPE, NULL, 0) <= 0)
>> +	if (vfs_getxattr(dentry, NFSD_JUNCTION_XATTR_NAME, NULL, 0) <= 0)
>> 		return 0;
>> 	return 1;
>> }
>> 
> --
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-- 
Chuck Lever
chuck[dot]lever[at]oracle[dot]com