In e9964c10 we change cap flushing to do a delicate dance because some
inodes on the cap_dirty list could be in a migrating state (got EXPORT but
not IMPORT) in which we couldn't actually flush and move from
dirty->flushing, breaking the while (!empty) { process first } loop
structure.  It worked for a single sync thread, but was not reentrant and
triggered infinite loops when multiple syncers came along.

Instead, move inodes with dirty to a separate cap_dirty_migrating list
when in the limbo export-but-no-import state, allowing us to go back to
the simple loop structure (which was reentrant).  This is cleaner and more
robust.

Audited the cap_dirty users and this looks fine:
list_empty(&ci->i_dirty_item) is still a reliable indicator of whether we
have dirty caps (which list we're on is irrelevant) and list_del_init()
calls still do the right thing.

Signed-off-by: Sage Weil <sage@newdream.net>

The r_mds field is redundant, since we can find the same information at
r_session->s_mds, and when r_session is NULL then r_mds is meaningless.

Signed-off-by: Sage Weil <sage@newdream.net>

This implements the DIRLAYOUTHASH protocol feature, which passes the dir
layout over the wire from the MDS.  This gives the client knowledge
of the correct hash function to use for mapping dentries among dir
fragments.

Note that if this feature is _not_ present on the client but is on the
MDS, the client may misdirect requests.  This will result in a forward
and degrade performance.  It may also result in inaccurate NFS filehandle
generation, which will prevent fh resolution when the inode is not present
in the client cache and the parent directories have been fragmented.

Signed-off-by: Sage Weil <sage@newdream.net>

Previously the kernel client incorrectly assumed everything was a directory.

Signed-off-by: Herb Shiu <herb_shiu@tcloudcomputing.com>
Acked-by: Greg Farnum <gregf@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>

MDS requests can be rebuilt and resent in non-process context, but were
filling in uid/gid from current_fsuid/gid.  Put that information in the
request struct on request setup.

This fixes incorrect (and root) uid/gid getting set for requests that
are forwarded between MDSs, usually due to metadata migrations.

Signed-off-by: Sage Weil <sage@newdream.net>

This factors out protocol and low-level storage parts of ceph into a
separate libceph module living in net/ceph and include/linux/ceph.  This
is mostly a matter of moving files around.  However, a few key pieces
of the interface change as well:

 - ceph_client becomes ceph_fs_client and ceph_client, where the latter
   captures the mon and osd clients, and the fs_client gets the mds client
   and file system specific pieces.
 - Mount option parsing and debugfs setup is correspondingly broken into
   two pieces.
 - The mon client gets a generic handler callback for otherwise unknown
   messages (mds map, in this case).
 - The basic supported/required feature bits can be expanded (and are by
   ceph_fs_client).

No functional change, aside from some subtle error handling cases that got
cleaned up in the refactoring process.

Signed-off-by: Sage Weil <sage@newdream.net>

The use of a completion when waiting for session shutdown during umount is
inappropriate, given the complexity of the condition.  For multiple MDS's,
this resulted in the umount thread spinning, often preventing the session
close message from being processed in some cases.

Switch to a waitqueue and defined a condition helper.  This cleans things
up nicely.

Signed-off-by: Sage Weil <sage@newdream.net>

Signed-off-by: Greg Farnum <gregf@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>

When we get a cap EXPORT message, make sure we are connected to all export
targets to ensure we can handle the matching IMPORT.

Signed-off-by: Sage Weil <sage@newdream.net>

Caps related accounting is now being done per mds client instead
of just being global. This prepares ground work for a later revision
of the caps preallocated reservation list.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>