ceph: new device mount syntax

Old mount device syntax (source) has the following problems:

- mounts to the same cluster but with different fsnames
  and/or creds have identical device string which can
  confuse xfstests.

- Userspace mount helper tool resolves monitor addresses
  and fill in mon addrs automatically, but that means the
  device shown in /proc/mounts is different than what was
  used for mounting.

New device syntax is as follows:

  cephuser@fsid.mycephfs2=/path

Note, there is no "monitor address" in the device string.
That gets passed in as mount option. This keeps the device
string same when monitor addresses change (on remounts).

Also note that the userspace mount helper tool is backward
compatible. I.e., the mount helper will fallback to using
old syntax after trying to mount with the new syntax.

[ idryomov: drop CEPH_MON_ADDR_MNTOPT_DELIM ]

Signed-off-by: Venky Shankar <vshankar@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index ac331aa07cfa..ec6b221e5b62 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -89,6 +89,8 @@ struct ceph_mount_options {
 	unsigned int max_readdir;       /* max readdir result (entries) */
 	unsigned int max_readdir_bytes; /* max readdir result (bytes) */
 
+	bool new_dev_syntax;
+
 	/*
 	 * everything above this point can be memcmp'd; everything below
 	 * is handled in compare_mount_options()
@@ -98,6 +100,7 @@ struct ceph_mount_options {
 	char *mds_namespace;  /* default NULL */
 	char *server_path;    /* default NULL (means "/") */
 	char *fscache_uniq;   /* default NULL */
+	char *mon_addr;
 };
 
 struct ceph_fs_client {