ceph: add getvxattr op

Problem:
Some directory vxattrs (e.g. ceph.dir.pin.random) are governed by
information that isn't necessarily shared with the client. Add support
for the new GETVXATTR operation, which allows the client to query the
MDS directly for vxattrs.
When the client is queried for a vxattr that doesn't have a special
handler, have it issue a GETVXATTR to the MDS directly.

Solution:
Adds new getvxattr op to fetch ceph.dir.pin*, ceph.dir.layout* and
ceph.file.layout* vxattrs.
If the entire layout for a dir or a file is being set, then it is
expected that the layout be set in standard JSON format. Individual
field value retrieval is not wrapped in JSON. The JSON format also
applies while setting the vxattr if the entire layout is being set in
one go.
As a temporary measure, setting a vxattr can also be done in the old
format. The old format will be deprecated in the future.

URL: https://tracker.ceph.com/issues/51062
Signed-off-by: Milind Changire <mchangir@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/fs/ceph/xattr.c b/fs/ceph/xattr.c
index fcf7dfdecf96..afec84088471 100644
--- a/fs/ceph/xattr.c
+++ b/fs/ceph/xattr.c
@@ -923,10 +923,13 @@ ssize_t __ceph_getxattr(struct inode *inode, const char *name, void *value,
 {
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	struct ceph_inode_xattr *xattr;
-	struct ceph_vxattr *vxattr = NULL;
+	struct ceph_vxattr *vxattr;
 	int req_mask;
 	ssize_t err;
 
+	if (strncmp(name, XATTR_CEPH_PREFIX, XATTR_CEPH_PREFIX_LEN))
+		goto handle_non_vxattrs;
+
 	/* let's see if a virtual xattr was requested */
 	vxattr = ceph_match_vxattr(inode, name);
 	if (vxattr) {
@@ -945,8 +948,14 @@ ssize_t __ceph_getxattr(struct inode *inode, const char *name, void *value,
 				err = -ERANGE;
 		}
 		return err;
+	} else {
+		err = ceph_do_getvxattr(inode, name, value, size);
+		/* this would happen with a new client and old server combo */
+		if (err == -EOPNOTSUPP)
+			err = -ENODATA;
+		return err;
 	}
-
+handle_non_vxattrs:
 	req_mask = __get_request_mask(inode);
 
 	spin_lock(&ci->i_ceph_lock);