reiserfs: switch to generic_{get,set,remove}xattr()

reiserfs_xattr_[sg]et() will fail with -EOPNOTSUPP for V1 inodes anyway,
and all reiserfs instances of ->[sg]et() call it and so does ->set_acl().

Checks for name length in the instances had been bogus; they should've
been "bugger off if it's _exactly_ the prefix" (as generic would
do on its own) and not "bugger off if it's shorter than the prefix" -
that can't happen.

xattr_full_name() is needed to adjust for the fact that generic instances
will skip the prefix in the name passed to ->[gs]et(); reiserfs homegrown
analogues didn't.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/reiserfs/xattr_trusted.c b/fs/reiserfs/xattr_trusted.c
index 64b67aa..cc248a5 100644
--- a/fs/reiserfs/xattr_trusted.c
+++ b/fs/reiserfs/xattr_trusted.c
@@ -11,26 +11,24 @@
 trusted_get(const struct xattr_handler *handler, struct dentry *dentry,
 	    const char *name, void *buffer, size_t size)
 {
-	if (strlen(name) < sizeof(XATTR_TRUSTED_PREFIX))
-		return -EINVAL;
-
 	if (!capable(CAP_SYS_ADMIN) || IS_PRIVATE(d_inode(dentry)))
 		return -EPERM;
 
-	return reiserfs_xattr_get(d_inode(dentry), name, buffer, size);
+	return reiserfs_xattr_get(d_inode(dentry),
+				  xattr_full_name(handler, name),
+				  buffer, size);
 }
 
 static int
 trusted_set(const struct xattr_handler *handler, struct dentry *dentry,
 	    const char *name, const void *buffer, size_t size, int flags)
 {
-	if (strlen(name) < sizeof(XATTR_TRUSTED_PREFIX))
-		return -EINVAL;
-
 	if (!capable(CAP_SYS_ADMIN) || IS_PRIVATE(d_inode(dentry)))
 		return -EPERM;
 
-	return reiserfs_xattr_set(d_inode(dentry), name, buffer, size, flags);
+	return reiserfs_xattr_set(d_inode(dentry),
+				  xattr_full_name(handler, name),
+				  buffer, size, flags);
 }
 
 static bool trusted_list(struct dentry *dentry)