afs: Rearrange status mapping

Rearrange the AFSFetchStatus to inode attribute mapping code in a number of
ways:

 (1) Use an XDR structure rather than a series of incremented pointer
     accesses when decoding an AFSFetchStatus object.  This allows
     out-of-order decode.

 (2) Don't store the if_version value but rather just check it and abort if
     it's not something we can handle.

 (3) Store the owner and group in the status record as raw values rather
     than converting them to kuid/kgid.  Do that when they're mapped into
     i_uid/i_gid.

 (4) Validate the type and abort code up front and abort if they're wrong.

 (5) Split the inode attribute setting out into its own function from the
     XDR decode of an AFSFetchStatus object.  This allows it to be called
     from elsewhere too.

 (6) Differentiate changes to data from changes to metadata.

 (7) Use the split-out attribute mapping function from afs_iget().

Signed-off-by: David Howells <dhowells@redhat.com>

fs/afs/afs.h

@@ -131,15 +131,13 @@ struct afs_file_status {
 	afs_dataversion_t	data_version;	/* current data version */
 	time_t			mtime_client;	/* last time client changed data */
 	time_t			mtime_server;	/* last time server changed data */
-	unsigned		if_version;	/* interface version */
-#define AFS_FSTATUS_VERSION	1
 	unsigned		abort_code;	/* Abort if bulk-fetching this failed */
 
 	afs_file_type_t		type;		/* file type */
 	unsigned		nlink;		/* link count */
 	u32			author;		/* author ID */
-	kuid_t			owner;		/* owner ID */
-	kgid_t			group;		/* group ID */
+	u32			owner;		/* owner ID */
+	u32			group;		/* group ID */
 	afs_access_t		caller_access;	/* access rights for authenticated caller */
 	afs_access_t		anon_access;	/* access rights for unauthenticated caller */
 	umode_t			mode;		/* UNIX mode */