ceph: Switch to generic xattr handlers

Add a catch-all xattr handler at the end of ceph_xattr_handlers.  Check
for valid attribute names there, and remove those checks from
__ceph_{get,set,remove}xattr instead.  No "system.*" xattrs need to be
handled by the catch-all handler anymore.

The set xattr handler is called with a NULL value to indicate that the
attribute should be removed; __ceph_setxattr already handles that case
correctly (ceph_set_acl could already calling __ceph_setxattr with a NULL
value).

Move the check for snapshots from ceph_{set,remove}xattr into
__ceph_{set,remove}xattr.  With that, ceph_{get,set,remove}xattr can be
replaced with the generic iops.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index cadb6ae..addf8ef 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -8,6 +8,7 @@
 #include <linux/kernel.h>
 #include <linux/writeback.h>
 #include <linux/vmalloc.h>
+#include <linux/xattr.h>
 #include <linux/posix_acl.h>
 #include <linux/random.h>
 
@@ -92,10 +93,10 @@
 	.permission = ceph_permission,
 	.setattr = ceph_setattr,
 	.getattr = ceph_getattr,
-	.setxattr = ceph_setxattr,
-	.getxattr = ceph_getxattr,
+	.setxattr = generic_setxattr,
+	.getxattr = generic_getxattr,
 	.listxattr = ceph_listxattr,
-	.removexattr = ceph_removexattr,
+	.removexattr = generic_removexattr,
 	.get_acl = ceph_get_acl,
 	.set_acl = ceph_set_acl,
 };
@@ -1770,10 +1771,10 @@
 	.get_link = simple_get_link,
 	.setattr = ceph_setattr,
 	.getattr = ceph_getattr,
-	.setxattr = ceph_setxattr,
-	.getxattr = ceph_getxattr,
+	.setxattr = generic_setxattr,
+	.getxattr = generic_getxattr,
 	.listxattr = ceph_listxattr,
-	.removexattr = ceph_removexattr,
+	.removexattr = generic_removexattr,
 };
 
 int __ceph_setattr(struct inode *inode, struct iattr *attr)