Commit Graph

262 Commits

Author SHA1 Message Date
Sage Weil
3d8eb7a94e ceph: remove unnecessary d_fsdata conditional checks
We now set d_fsdata unconditionally on all dentries prior to setting up
the d_ops, so all of these checks are unnecessary.

Signed-off-by: Sage Weil <sage@newdream.net>
2012-01-10 08:56:56 -08:00
Yehuda Sadeh
9d5a09e659 ceph: add missing spin_unlock at ceph_mdsc_build_path()
one of the paths was missing spin_unlock

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
2011-12-13 11:59:53 -08:00
Sage Weil
be655596b3 ceph: use i_ceph_lock instead of i_lock
We have been using i_lock to protect all kinds of data structures in the
ceph_inode_info struct, including lists of inodes that we need to iterate
over while avoiding races with inode destruction.  That requires grabbing
a reference to the inode with the list lock protected, but igrab() now
takes i_lock to check the inode flags.

Changing the list lock ordering would be a painful process.

However, using a ceph-specific i_ceph_lock in the ceph inode instead of
i_lock is a simple mechanical change and avoids the ordering constraints
imposed by igrab().

Reported-by: Amon Ott <a.ott@m-privacy.de>
Signed-off-by: Sage Weil <sage@newdream.net>
2011-12-07 10:46:44 -08:00
H Hartley Sweeten
7fd7d101ff ceph/mds_client.c: quiet sparse noise
Quiet the following sparse noise:

warning: symbol 'get_nonsnap_parent' was not declared. Should it be static?
warning: symbol 'done_closing_sessions' was not declared. Should it be static?

Local functions don't need external visability. Make them static.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Sage Weil <sage@newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2011-11-05 21:10:11 -07:00
Sage Weil
c6ffe10015 ceph: use new D_COMPLETE dentry flag
We used to use a flag on the directory inode to track whether the dcache
contents for a directory were a complete cached copy.  Switch to a dentry
flag CEPH_D_COMPLETE that is safely updated by ->d_prune().

Signed-off-by: Sage Weil <sage@newdream.net>
2011-11-05 21:10:10 -07:00
Sage Weil
b61c27636f libceph: don't complain on msgpool alloc failures
The pool allocation failures are masked by the pool; there is no need to
spam the console about them.  (That's the whole point of having the pool
in the first place.)

Mark msg allocations whose failure is safely handled as such.

Signed-off-by: Sage Weil <sage@newdream.net>
2011-10-25 16:10:15 -07:00
Sage Weil
795858dbd2 ceph: fix encoding of ino only (not relative) paths
A 'path' consists of a starting ino and relative component.  Encode even
when there is no relative component.  This is primarily needed by the
NFS reexport code.

Signed-off-by: Sage Weil <sage@newdream.net>
2011-08-15 13:03:56 -07:00
Sage Weil
d79698da32 ceph: document unlocked d_parent accesses
For the most part we don't care about racing with rename when directing
MDS requests; either the old or new parent is fine.  Document that, and
do some minor cleanup.

Reviewed-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2011-07-26 11:31:26 -07:00
Sage Weil
41b02e1f9b ceph: explicitly reference rename old_dentry parent dir in request
We carry a pin on the parent directory for the rename source and dest
dentries.  For the source it's r_locked_dir; we need to explicitly
reference the old_dentry parent as well, since the dentry's d_parent may
change between when the request was created and pinned and when it is
freed.

Reviewed-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2011-07-26 11:31:14 -07:00
Sage Weil
e5f86dc377 ceph: avoid d_parent in ceph_dentry_hash; fix ceph_encode_fh() hashing bug
Have caller pass in a safely-obtained reference to the parent directory
for calculating a dentry's hash valud.

While we're here, simpify the flow through ceph_encode_fh() so that there
is a single exit point and cleanup.

Also fix a bug with the dentry hash calculation: calculate the hash for the
dentry we were given, not its parent.

Reviewed-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2011-07-26 11:30:55 -07:00
Sage Weil
2f90b852e3 ceph: ignore lease mask
The lease mask is no longer used (and it changed a while back).  Instead,
use a non-zero duration to indicate that there is a lease being issued.

Reviewed-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2011-07-26 11:28:25 -07:00
Al Viro
1b71fe2efa ceph analog of cifs build_path_from_dentry() race fix
... unfortunately, cifs bug got copied.  Fix is essentially the same.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-07-16 23:43:58 -04:00
Sage Weil
db3540522e ceph: fix cap flush race reentrancy
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>
2011-05-24 11:52:12 -07:00
Sage Weil
1b36698577 libceph: remove unused variable
Signed-off-by: Sage Weil <sage@newdream.net>
2011-05-19 11:24:17 -07:00
Sage Weil
3b66378034 ceph: take reference on mds request r_unsafe_dir
We put ourselves on an inode list for the parent directory of metadata
operations so that an fsync on the directory will wait for metadata updates
to commit to disk.  We weren't holding a reference to that directory,
however, and under certain workloads (fsstress in this case) the directory
can go away.

Signed-off-by: Sage Weil <sage@newdream.net>
2011-05-19 11:20:07 -07:00
Henry C Chang
7d8e18a69d ceph: print debug message before put mds session
The mds session, s, could be freed during ceph_put_mds_session.
Move dout before ceph_put_mds_session.

Signed-off-by: Henry C Chang <henry.cy.chang@gmail.com>
Signed-off-by: Sage Weil <sage@newdream.net>
2011-05-11 10:44:34 -07:00
Sage Weil
ef550f6f4f ceph: flush msgr_wq during mds_client shutdown
The release method for mds connections uses a backpointer to the
mds_client, so we need to flush the workqueue of any pending work (and
ceph_connection references) prior to freeing the mds_client.  This fixes
an oops easily triggered under UML by

 while true ; do mount ... ; umount ... ; done

Also fix an outdated comment: the flush in ceph_destroy_client only flushes
OSD connections out.  This bug is basically an artifact of the ceph ->
ceph+libceph conversion.

Signed-off-by: Sage Weil <sage@newdream.net>
2011-03-25 13:27:48 -07:00
Linus Torvalds
b12ece7d85 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  ceph: avoid picking MDS that is not active
  ceph: avoid immediate cap check after import
  ceph: fix flushing of caps vs cap import
  ceph: fix erroneous cap flush to non-auth mds
  ceph: fix cap_wanted_delay_{min,max} mount option initialization
  ceph: fix xattr rbtree search
  ceph: fix getattr on directory when using norbytes
2011-01-28 12:12:58 +10:00
Sage Weil
d66bbd441c ceph: avoid picking MDS that is not active
Ignore replication or auth frag data if it indicates an MDS that is not
active.  This can happen if the MDS shuts down and the client has stale
data about the namespace distribution across the MDS cluster.  If that's
the case, fall back to directing the request based on the auth cap (which
should always be accurate).

Signed-off-by: Sage Weil <sage@newdream.net>
2011-01-25 08:16:37 -08:00
Linus Torvalds
a170315420 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  rbd: fix cleanup when trying to mount inexistent image
  net/ceph: make ceph_msgr_wq non-reentrant
  ceph: fsc->*_wq's aren't used in memory reclaim path
  ceph: Always free allocated memory in osdmap_decode()
  ceph: Makefile: Remove unnessary code
  ceph: associate requests with opening sessions
  ceph: drop redundant r_mds field
  ceph: implement DIRLAYOUTHASH feature to get dir layout from MDS
  ceph: add dir_layout to inode
2011-01-13 10:25:24 -08:00
Sage Weil
dc69e2e9fc ceph: associate requests with opening sessions
Associate request with sessions that aren't yep open.  This makes the
debugfs mdsc request list more informative.

Signed-off-by: Sage Weil <sage@newdream.net>
2011-01-12 15:15:13 -08:00
Sage Weil
4af25fdda6 ceph: drop redundant r_mds field
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>
2011-01-12 15:15:13 -08:00
Sage Weil
14303d20f3 ceph: implement DIRLAYOUTHASH feature to get dir layout from MDS
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>
2011-01-12 15:15:13 -08:00
Nick Piggin
b7ab39f631 fs: dcache scale dentry refcount
Make d_count non-atomic and protect it with d_lock. This allows us to ensure a
0 refcount dentry remains 0 without dcache_lock. It is also fairly natural when
we start protecting many other dentry members with d_lock.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07 17:50:21 +11:00
Herb Shiu
25933abdd8 ceph: Handle file locks in replies from the MDS.
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>
2010-12-01 14:22:27 -08:00
Linus Torvalds
76db8ac45f Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  ceph: fix readdir EOVERFLOW on 32-bit archs
  ceph: fix frag offset for non-leftmost frags
  ceph: fix dangling pointer
  ceph: explicitly specify page alignment in network messages
  ceph: make page alignment explicit in osd interface
  ceph: fix comment, remove extraneous args
  ceph: fix update of ctime from MDS
  ceph: fix version check on racing inode updates
  ceph: fix uid/gid on resent mds requests
  ceph: fix rdcache_gen usage and invalidate
  ceph: re-request max_size if cap auth changes
  ceph: only let auth caps update max_size
  ceph: fix open for write on clustered mds
  ceph: fix bad pointer dereference in ceph_fill_trace
  ceph: fix small seq message skipping
  Revert "ceph: update issue_seq on cap grant"
2010-11-19 15:32:22 -08:00
Arnd Bergmann
451a3c24b0 BKL: remove extraneous #include <smp_lock.h>
The big kernel lock has been removed from all these files at some point,
leaving only the #include.

Remove this too as a cleanup.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-11-17 08:59:32 -08:00
Sage Weil
cb4276cca4 ceph: fix uid/gid on resent mds requests
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>
2010-11-08 07:29:05 -08:00
Sage Weil
496e59553c ceph: switch from BKL to lock_flocks()
Switch from using the BKL explicitly to the new lock_flocks() interface.
Eventually this will turn into a spinlock.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-10-20 15:38:18 -07:00
Greg Farnum
fca4451acf ceph: preallocate flock state without locks held
When the lock_kernel() turns into lock_flocks() and a spinlock, we won't
be able to do allocations with the lock held.  Preallocate space without
the lock, and retry if the lock state changes out from underneath us.

Signed-off-by: Greg Farnum <gregf@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-10-20 15:38:17 -07:00
Yehuda Sadeh
3d14c5d2b6 ceph: factor out libceph from Ceph file system
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>
2010-10-20 15:37:28 -07:00
Sage Weil
3612abbd5d ceph: fix reconnect encoding for old servers
Fix the reconnect encoding to encode the cap record when the MDS does not
have the FLOCK capability (i.e., pre v0.22).

Signed-off-by: Sage Weil <sage@newdream.net>
2010-09-11 10:52:47 -07:00
Sage Weil
e072f8aa35 ceph: don't BUG on ENOMEM during mds reconnect
We are in a position to return an error; do that instead.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-26 09:26:37 -07:00
Sage Weil
eb6bb1c5bd ceph: direct requests in snapped namespace based on nonsnap parent
When making a request in the virtual snapdir or a snapped portion of the
namespace, we should choose the MDS based on the first nonsnap parent (and
its caps).  If that is not the best place, we will get forward hints to
find the right MDS in the cluster.  This fixes ESTALE errors when using
the .snap directory and namespace with multiple MDSs.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-22 15:16:48 -07:00
Sage Weil
f3c60c5918 ceph: fix multiple mds session shutdown
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>
2010-08-22 15:04:43 -07:00
Sage Weil
213c99ee0c ceph: whitespace cleanup
Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-03 10:25:11 -07:00
Greg Farnum
40819f6fb2 ceph: add flock/fcntl lock support
Implement flock inode operation to support advisory file locking.  All
lock/unlock operations are synchronous with the MDS.  Lock state is
sent when reconnecting to a recovering MDS to restore the shared lock
state.

Signed-off-by: Greg Farnum <gregf@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-02 16:10:53 -07:00
Sage Weil
20cb34ae9e ceph: support v2 reconnect encoding
Encode either old or v2 encoding of client_reconnect message, depending on
whether the peer has the FLOCK feature bit.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-02 15:48:50 -07:00
Greg Farnum
e55b71f802 ceph: handle ESTALE properly; on receipt send to authority if it wasn't
Signed-off-by: Greg Farnum <gregf@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:41 -07:00
Sage Weil
154f42c2c3 ceph: connect to export targets on cap export
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>
2010-08-01 20:11:41 -07:00
Sage Weil
cb170a2215 ceph: connect to export targets if mds is laggy
If an MDS we are talking to may have failed, we need to open sessions to
its potential export targets to ensure that any in-progress migration that
may have involved some of our caps is properly handled.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:40 -07:00
Sage Weil
ed0552a1a2 ceph: introduce helper to connect to mds export targets
There are a few cases where we need to open sessions with a given mds's
potential export targets.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:40 -07:00
Yehuda Sadeh
37151668ba ceph: do caps accounting per mds_client
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>
2010-08-01 20:11:40 -07:00
Sage Weil
0deb01c999 ceph: track laggy state of mds from mdsmap
Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:40 -07:00
Sage Weil
38e8883ee3 ceph: simplify add_cap_releases
No functional change, aside from more useful debug output.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:39 -07:00
Sage Weil
ee6b272b9c ceph: drop unused argument
Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:39 -07:00
Yehuda Sadeh
03066f2345 ceph: use complete_all and wake_up_all
This fixes an issue triggered by running concurrent syncs. One of the syncs
would go through while the other would just hang indefinitely. In any case, we
never actually want to wake a single waiter, so the *_all functions should
be used.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-07-27 13:11:17 -07:00
Sage Weil
e979cf5039 ceph: do not include cap/dentry releases in replayed messages
Strip the cap and dentry releases from replayed messages.  They can
cause the shared state to get out of sync because they were generated
(with the request message) earlier, and no longer reflect the current
client state.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-07-16 10:30:18 -07:00
Sage Weil
01a92f174f ceph: reuse request message when replaying against recovering mds
Replayed rename operations (after an mds failure/recovery) were broken
because the request paths were regenerated from the dentry names, which
get mangled when d_move() is called.

Instead, resend the previous request message when replaying completed
operations.  Just make sure the REPLAY flag is set and the target ino is
filled in.

This fixes problems with workloads doing renames when the MDS restarts,
where the rename operation appears to succeed, but on mds restart then
fails (leading to client confusion, app breakage, etc.).

Signed-off-by: Sage Weil <sage@newdream.net>
2010-07-16 10:30:17 -07:00
Sage Weil
17c688c3df ceph: delay umount until all mds requests drop inode+dentry refs
This fixes a race between handle_reply finishing an mds request, signalling
completion, and then dropping the request structing and its dentry+inode
refs, and pre_umount function waiting for requests to finish before
letting the vfs tear down the dcache.  If umount was delayed waiting for
mds requests, we could race and BUG in shrink_dcache_for_umount_subtree
because of a slow dput.

This delays umount until the msgr queue flushes, which means handle_reply
will exit and will have dropped the ceph_mds_request struct.  I'm assuming
the VFS has already ensured that its calls have all completed and those
request refs have thus been dropped as well (I haven't seen that race, at
least).

Signed-off-by: Sage Weil <sage@newdream.net>
2010-06-21 16:11:50 -07:00
Sage Weil
2b2300d62e ceph: try to send partial cap release on cap message on missing inode
If we have enough memory to allocate a new cap release message, do so, so
that we can send a partial release message immediately.  This keeps us from
making the MDS wait when the cap release it needs is in a partially full
release message.

If we fail because of ENOMEM, oh well, they'll just have to wait a bit
longer.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-06-10 13:30:25 -07:00
Sage Weil
3d7ded4d81 ceph: release cap on import if we don't have the inode
If we get an IMPORT that give us a cap, but we don't have the inode, queue
a release (and try to send it immediately) so that the MDS doesn't get
stuck waiting for us.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-06-10 13:30:07 -07:00
Sage Weil
1e5ea23df1 ceph: fix lease revocation when seq doesn't match
If the client revokes a lease with a higher seq than what we have, keep
the mds's seq, so that it honors our release.  Otherwise, we can hang
indefinitely.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-06-04 10:05:40 -07:00
Sage Weil
2a8e5e3637 ceph: clean up on forwarded aborted mds request
If an mds request is aborted (timeout, SIGKILL), it is left registered to
keep our state in sync with the mds.  If we get a forward notification,
though, we know the request didn't succeed and we can unregister it
safely.  We were trying to resend it, but then bailing out (and not
unregistering) in __do_request.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-29 09:42:05 -07:00
Sage Weil
dd1c905736 ceph: make lease code DN specific
The lease code includes a mask in the CEPH_LOCK_* namespace, but that
namespace is changing, and only one mask (formerly _DN == 1) is used, so
hard code for that value for now.

If we ever extend this code to handle leases over different data types we
can extend it accordingly.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-29 09:12:42 -07:00
Sage Weil
aa91647c89 ceph: make mds requests killable, not interruptible
The underlying problem is that many mds requests can't be restarted.  For
example, a restarted create() would return -EEXIST if the original request
succeeds.  However, we do not want a hung MDS to hang the client too.  So,
use the _killable wait_for_completion variants to abort on SIGKILL but
nothing else.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-29 09:12:35 -07:00
Tobias Klauser
9e32789f63 ceph: Storage class should be before const qualifier
The C99 specification states in section 6.11.5:

The placement of a storage-class specifier other than at the beginning
of the declaration specifiers in a declaration is an obsolescent
feature.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-21 15:01:21 -07:00
Yehuda Sadeh
34d23762d9 ceph: all allocation functions should get gfp_mask
This is essential, as for the rados block device we'll need
to run in different contexts that would need flags that
are other than GFP_NOFS.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 15:25:42 -07:00
Sage Weil
167c9e352d ceph: use common helper for aborted dir request invalidation
We invalidate I_COMPLETE and dentry leases in two places: on aborted mds
request and on request replay.  Use common helper to avoid duplicate code.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 15:25:40 -07:00
Sage Weil
85792d0dd6 ceph: cope with out of order (unsafe after safe) mds reply
Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 15:25:39 -07:00
Sage Weil
6c99f2545d ceph: throw out dirty caps metadata, data on session teardown
The remove_session_caps() helper is called when an MDS closes out our
session (either normally, or as a result of a failed reconnect), and when
we tear down state for umount.  If we remove the last cap, and there are
no cap migrations in progress, then there is little hope of us flushing
out that data to the mds (without heroic efforts to reconnect and flush).

So, to avoid leaving inodes pinned (due to dirty state) and crashing after
umount, throw out dirty caps state and unpin the inodes.  Print a warning
to the console so we know something was lost.

NOTE: Although we drop wrbuffer refs, we don't actually mark pages clean;
maybe a truncate should be queued?

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 15:25:37 -07:00
Sage Weil
7e70f0ed9f ceph: attempt mds reconnect if mds closes our session
Currently, if our session is closed (due to a timeout, or explicit close,
or whatever), we just sit there doing nothing unless/until the MDS
restarts, at which point we try to reconnect.

Change client to attempt an immediate reconnect if our session is closed.

Note that currently the MDS doesn't support this, and our attempt will
fail.  We'll get a session CLOSE, our caps and dirty cap state will be
dropped, and the client will be free to attempt to reconnect.  That's
clearly not as nice as a successful reconnect, but it at least allows us
to try to carry on, and in the future the MDS will support a reconnect
and we will fare better.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 15:25:36 -07:00
Sage Weil
34b6c855fa ceph: clean up send_mds_reconnect interface
Pass a ceph_mds_session, since the caller has it.

Remove the dead code for sending empty reconnects.  It used to be used
when the MDS contacted _us_ to solicit a reconnect, and we could reply
saying "go away, I have no session."  Now we only send reconnects based
on the mds map, and only when we do in fact have an open session.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 15:25:35 -07:00
Sage Weil
29790f26ab ceph: wait for mds OPEN reply to indicate reconnect success
We used to infer reconnect success by watching the MDS state, essentially
assuming that hearing nothing meant things were ok.  That wasn't
particularly reliable.  Instead, the MDS replies with an explicit OPEN
message to indicate success.

Strictly speaking, this is a protocol change, but it is a backwards
compatible one that does not break new clients + old servers or old
clients + new servers.  At least not yet.

Drop unused @all argument from kick_requests while we're at it.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 15:25:35 -07:00
Sage Weil
aab53dd9e8 ceph: only send cap releases when mds is OPEN|HUNG
On OPENING we shouldn't have any caps (or releases).
On CLOSING, we should wait until we succeed (and throw it all out), or
don't (and are OPEN again).
On RECONNECTING we can wait until we are OPEN.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 15:25:34 -07:00
Sage Weil
e01a594646 ceph: dicard cap releases on mds restart
If the MDS restarts, the expire caps state is no longer shared, and can be
thrown out.  Caps state will be rebuilt on the MDS during the reconnect
process that follows.  Zero out any release messages and adjust the
release counter accordingly.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 15:25:33 -07:00
Sage Weil
0f8605f2bd ceph: clean up cap release loop vs spinlock
Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 15:25:31 -07:00
Sage Weil
56b7cf9581 ceph: skip mds sync on forced unmount
Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 15:25:30 -07:00
Sage Weil
bb257664f7 ceph: simplify ceph_msg_new
We only need to pass in front_len.  Callers can attach any other payload
pieces (middle, data) as they see fit.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 15:25:19 -07:00
Sage Weil
a79832f26b ceph: make ceph_msg_new return NULL on failure; clean up, fix callers
Returning ERR_PTR(-ENOMEM) is useless extra work.  Return NULL on failure
instead, and fix up the callers (about half of which were wrong anyway).

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 15:25:18 -07:00
Cheng Renquan
2d06eeb877 ceph: handle kzalloc() failure
Signed-off-by: Cheng Renquan <crquan@gmail.com>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 15:25:16 -07:00
Sage Weil
104648ad3f ceph: reduce build_path debug output
Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 15:25:13 -07:00
Sage Weil
81a6cf2d30 ceph: invalidate affected dentry leases on aborted requests
If we abort a request, we return to caller, but the request may still
complete.  And if we hold the dir FILE_EXCL bit, we may not release a
lease when sending a request.  A simple un-tar, control-c, un-tar again
will reproduce the bug (manifested as a 'Cannot open: File exists').

Ensure we invalidate affected dentry leases (as well dir I_COMPLETE) so
we don't have valid (but incorrect) leases.  Do the same, consistently, at
other sites where I_COMPLETE is similarly cleared.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 10:25:45 -07:00
Sage Weil
b4556396fa ceph: fix race between aborted requests and fill_trace
When we abort requests we need to prevent fill_trace et al from doing
anything that relies on locks held by the VFS caller.  This fixes a race
between the reply handler and the abort code, ensuring that continue
holding the dir mutex until the reply handler completes.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 10:25:45 -07:00
Sage Weil
e1518c7c0a ceph: clean up mds reply, error handling
We would occasionally BUG out in the reply handler because r_reply was
nonzero, due to a race with ceph_mdsc_do_request temporarily setting
r_reply to an ERR_PTR value.  This is unnecessary, messy, and also wrong
in the EIO case.

Clean up by consistently using r_err for errors and r_reply for messages.
Also fix the abort logic to trigger consistently for all errors that return
to the caller early (e.g., EIO from timeout case).  If an abort races with
a reply, use the result from the reply.

Also fix locking for r_err, r_reply update in the reply handler.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 10:25:44 -07:00
Sage Weil
f818a73674 ceph: fix cap removal races
The iterate_session_caps helper traverses the session caps list and tries
to grab an inode reference.  However, the __ceph_remove_cap was clearing
the inode backpointer _before_ removing itself from the session list,
causing a null pointer dereference.

Clear cap->ci under protection of s_cap_lock to avoid the race, and to
tightly couple the list and backpointer state.  Use a local flag to
indicate whether we are releasing the cap, as cap->session may be modified
by a racing thread in iterate_session_caps.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-11 20:56:31 -07:00
Sage Weil
9abf82b8bc ceph: fix locking for waking session requests after reconnect
The session->s_waiting list is protected by mdsc->mutex, not s_mutex.  This
was causing (rare) s_waiting list corruption.

Fix errors paths too, while we're here.  A more thorough cleanup of this
function is coming soon.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-11 09:53:57 -07:00
Tejun Heo
5a0e3ad6af include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-30 22:02:32 +09:00
Sage Weil
94aa8ae13d ceph: fix use after free on mds __unregister_request
There was a use after free in __unregister_request that would trigger
whenever the request map held the last reference.  This appears to have
triggered an oops during 'umount -f' when requests are being torn down.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-03-28 21:23:56 -07:00
Sage Weil
d96d60498f ceph: fix session check on mds reply
Fix a broken check that a reply came back from the same MDS we sent the
request to.  I don't think a case that actually triggers this would ever
come up in practice, but it's clearly wrong and easy to fix.

Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-03-23 07:47:05 -07:00
Dan Carpenter
4736b009b8 ceph: handle kmalloc() failure
Return ERR_PTR(-ENOMEM) if kmalloc() fails.  We handle allocation
failures the same way later in the function.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-03-23 07:47:04 -07:00
Sage Weil
9c423956b8 ceph: propagate mds session allocation failures to caller
Return error to original caller if register_session() fails.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-03-23 07:47:04 -07:00
Sage Weil
e4cb4cb8a0 ceph: prevent dup stale messages to console for restarting mds
Prevent duplicate 'mds0 caps stale' message from spamming the console every
few seconds while the MDS restarts.  Set s_renew_requested earlier, so that
we only print the message once, even if we don't send an actual request.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-03-23 07:46:58 -07:00
Sage Weil
80fc7314a7 ceph: fix mds sync() race with completing requests
The wait_unsafe_requests() helper dropped the mdsc mutex to wait
for each request to complete, and then examined r_node to get the
next request after retaking the lock.  But the request completion
removes the request from the tree, so r_node was always undefined
at this point.  Since it's a small race, it usually led to a
valid request, but not always.  The result was an occasional
crash in rb_next() while dereferencing node->rb_left.

Fix this by clearing the rb_node when removing the request from
the request tree, and not walking off into the weeds when we
are done waiting for a request.  Since the request we waited on
will _always_ be out of the request tree, take a ref on the next
request, in the hopes that it won't be.  But if it is, it's ok:
we can start over from the beginning (and traverse over older read
requests again).

Signed-off-by: Sage Weil <sage@newdream.net>
2010-03-23 07:46:56 -07:00
Sage Weil
080af17e9c ceph: remove bogus mds forward warning
The must_resend flag is always true, not false.  In any case, we can
just ignore it anyway.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-02-26 10:02:03 -08:00
Sage Weil
a1ea787c7b ceph: fix client_request_forward decoding
The tid is in the message header, not body.  Broken since 6df058c0.

No need to look at next mds session; just mark the request and be done.
(The old error path was broken too, but now it's gone.)

Signed-off-by: Sage Weil <sage@newdream.net>
2010-02-23 14:26:36 -08:00
Sage Weil
2600d2dd50 ceph: drop messages on unregistered mds sessions; cleanup
Verify the mds session is currently registered before handling
incoming messages.  Clean up message handlers to pull mds out
of session->s_mds instead of less trustworthy src field.

Clean up con_{get,put} debug output.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-02-23 14:26:35 -08:00
Sage Weil
7c1332b8cb ceph: fix iterate_caps removal race
We need to be able to iterate over all caps on a session with a
possibly slow callback on each cap.  To allow this, we used to
prevent cap reordering while we were iterating.  However, we were
not safe from races with removal: removing the 'next' cap would
make the next pointer from list_for_each_entry_safe be invalid,
and cause a lock up or similar badness.

Instead, we keep an iterator pointer in the session pointing to
the current cap.  As before, we avoid reordering.  For removal,
if the cap isn't the current cap we are iterating over, we are
fine.  If it is, we clear cap->ci (to mark the cap as pending
removal) but leave it in the session list.  In iterate_caps, we
can safely finish removal and get the next cap pointer.

While we're at it, clean up put_cap to not take a cap reservation
context, as it was never used.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-02-17 10:02:47 -08:00
Sage Weil
a105f00cf1 ceph: use rbtree for snap_realms
Switch from radix tree to rbtree for snap realms.  This is much more
appropriate given that realm keys are few and far between.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-02-16 22:01:09 -08:00
Sage Weil
44ca18f268 ceph: use rbtree for mds requests
The rbtree is a more appropriate data structure than a radix_tree.  It
avoids extra memory usage and simplifies the code.

It also fixes a bug where the debugfs 'mdsc' file wasn't including the
most recent mds request.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-02-16 22:01:08 -08:00
Sage Weil
9bd2e6f8ba ceph: allow renewal of auth credentials
Add infrastructure to allow the mon_client to periodically renew its auth
credentials.  Also add a messenger callback that will force such a renewal
if a peer rejects our authenticator.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-02-10 15:04:47 -08:00
Sage Weil
ac8839d7b2 ceph: include type in ceph_entity_addr, filepath
Include a type/version in ceph_entity_addr and filepath.  Include extra
byte in filepath encoding as necessary.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-01-29 12:41:09 -08:00
Yehuda Sadeh
2450418c47 ceph: allocate middle of message before stating to read
Both front and middle parts of the message are now being
allocated at the ceph_alloc_msg().

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
2010-01-25 12:57:37 -08:00
Sage Weil
5b1daecd59 ceph: properly handle aborted mds requests
Previously, if the MDS request was interrupted, we would unregister the
request and ignore any reply.  This could cause the caps or other cache
state to become out of sync.  (For instance, aborting dbench and doing
rm -r on clients would complain about a non-empty directory because the
client didn't realize it's aborted file create request completed.)

Even we don't unregister, we still can't process the reply normally because
we are no longer holding the caller's locks (like the dir i_mutex).

So, mark aborted operations with r_aborted, and in the reply handler, be
sure to process all the caps.  Do not process the namespace changes,
though, since we no longer will hold the dir i_mutex.  The dentry lease
state can also be ignored as it's more forgiving.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-01-25 11:49:51 -08:00
Sage Weil
93cea5bebf ceph: use ceph_pagelist for mds reconnect message; change encoding (protocol change)
Use the ceph_pagelist to encode the MDS reconnect message.  We change the
message encoding (protocol change!) at the same time to make our life
easier (we don't know how many snaprealms we have when we start encoding).

An empty message implies the session is closed/does not exist.

Signed-off-by: Sage Weil <sage@newdream.net>
2009-12-23 12:21:51 -08:00
Sage Weil
6df058c025 ceph: include transaction id in ceph_msg_header (protocol change)
Many (most?) message types include a transaction id.  By including it in
the fixed size header, we always have it available even when we are unable
to allocate memory for the (larger, variable sized) message body.  This
will allow us to error out the appropriate request instead of (silently)
dropping the reply.

Signed-off-by: Sage Weil <sage@newdream.net>
2009-12-23 08:17:22 -08:00
Sage Weil
5dacf09121 ceph: do not touch_caps while iterating over caps list
Avoid confusing iterate_session_caps(), flag the session while we are
iterating so that __touch_cap does not rearrange items on the list.

All other modifiers of session->s_caps do so under the protection of
s_mutex.

Signed-off-by: Sage Weil <sage@newdream.net>
2009-12-23 08:17:14 -08:00
Sage Weil
e2885f06ce ceph: make mds ops interruptible
Signed-off-by: Sage Weil <sage@newdream.net>
2009-12-21 16:39:53 -08:00
Sage Weil
9ec7cab14e ceph: hex dump corrupt server data to KERN_DEBUG
Also, print fsid using standard format, NOT hex dump.

Signed-off-by: Sage Weil <sage@newdream.net>
2009-12-21 16:39:52 -08:00
Sage Weil
153c8e6bf7 ceph: use kref for struct ceph_mds_request
Signed-off-by: Sage Weil <sage@newdream.net>
2009-12-07 12:31:09 -08:00
Sage Weil
0dc2570fab ceph: reset requested max_size after mds reconnect
The max_size increase request to the MDS can get lost during an MDS
restart and reconnect.  Reset our requested value after the MDS recovers,
so that any blocked writes will re-request a larger max_size upon waking.

Also, explicit wake session caps after the reconnect.  Normally the cap
renewal catches this, but not in the cases where the caps didn't go stale
in the first place, which would leave writers waiting on max_size asleep.

Signed-off-by: Sage Weil <sage@newdream.net>
2009-11-20 14:24:52 -08:00
Sage Weil
0743304d87 ceph: fix debugfs entry, simplify fsid checks
We may first learn our fsid from any of the mon, osd, or mds maps
(whichever the monitor sends first).  Consolidate checks in a single
helper.  Initialize the client debugfs entry then, since we need the
fsid (and global_id) for the directory name.

Also remove dead mount code.

Signed-off-by: Sage Weil <sage@newdream.net>
2009-11-20 14:24:27 -08:00
Sage Weil
4e7a5dcd1b ceph: negotiate authentication protocol; implement AUTH_NONE protocol
When we open a monitor session, we send an initial AUTH message listing
the auth protocols we support, our entity name, and (possibly) a previously
assigned global_id.  The monitor chooses a protocol and responds with an
initial message.

Initially implement AUTH_NONE, a dummy protocol that provides no security,
but works within the new framework.  It generates 'authorizers' that are
used when connecting to (mds, osd) services that simply state our entity
name and global_id.

This is a wire protocol change.

Signed-off-by: Sage Weil <sage@newdream.net>
2009-11-18 16:19:57 -08:00
Sage Weil
5f44f14260 ceph: handle errors during osd client init
Unwind initializing if we get ENOMEM during client initialization.

Signed-off-by: Sage Weil <sage@newdream.net>
2009-11-18 15:02:36 -08:00
Sage Weil
42ce56e50d ceph: remove bad calls to ceph_con_shutdown
We want to ceph_con_close when we're done with the connection, before
the ref count reaches 0.  Once it does, do not call ceph_con_shutdown,
as that takes the con mutex and may sleep, and besides that is
unnecessary.

Signed-off-by: Sage Weil <sage@newdream.net>
2009-11-18 11:29:42 -08:00
Sage Weil
fef320ff88 ceph: pr_info when mds reconnect completes
This helps the user know what's going on during the (involved) reconnect
process.  They already see when the mds fails and reconnect starts.

Signed-off-by: Sage Weil <sage@newdream.net>
2009-11-11 15:50:31 -08:00
Sage Weil
cdac830313 ceph: remove recon_gen logic
We don't get an explicit affirmative confirmation that our caps reconnect,
nor do we necessarily want to pay that cost.  So, take all this code out
for now.

Signed-off-by: Sage Weil <sage@newdream.net>
2009-11-10 16:03:53 -08:00
Sage Weil
685f9a5d14 ceph: do not confuse stale and dead (unreconnected) caps
We were using the cap_gen to track both stale caps (caps that timed out
due to temporarily losing touch with the mds) and dead caps that did not
reconnect after an MDS failure.  Introduce a recon_gen counter to track
reconnections to restarted MDSs and kill dead caps based on that instead.

Rename gen to cap_gen while we're at it to make it more clear which is
which.

Signed-off-by: Sage Weil <sage@newdream.net>
2009-11-09 12:06:07 -08:00
Sage Weil
6b8051855d ceph: allocate and parse mount args before client instance
This simplifies much of the error handling during mount.  It also means
that we have the mount args before client creation, and we can initialize
based on those options.

Signed-off-by: Sage Weil <sage@newdream.net>
2009-10-27 11:57:03 -07:00
Sage Weil
afcdaea3f2 ceph: flush dirty caps via the cap_dirty list
Previously we were flushing dirty caps by passing an extra flag
when traversing the delayed caps list.  Besides being a bit ugly,
that can also miss caps that are dirty but didn't result in a
cap requeue: notably, mark_caps_dirty().

Separate the flushing into a separate helper, and traverse the
cap_dirty list.

This also brings i_dirty_item in line with i_dirty_caps: we are
on the list IFF caps != 0.  We carry an inode ref IFF
dirty_caps|flushing_caps != 0.

Lose the unused return value from __ceph_mark_caps_dirty().

Signed-off-by: Sage Weil <sage@newdream.net>
2009-10-15 18:14:35 -07:00
Sage Weil
c89136ea42 ceph: convert encode/decode macros to inlines
This avoids the fugly pass by reference and makes the code a bit easier
to read.

Signed-off-by: Sage Weil <sage@newdream.net>
2009-10-14 09:59:09 -07:00
Sage Weil
2f2dc05340 ceph: MDS client
The MDS (metadata server) client is responsible for submitting
requests to the MDS cluster and parsing the response.  We decide which
MDS to submit each request to based on cached information about the
current partition of the directory hierarchy across the cluster.  A
stateful session is opened with each MDS before we submit requests to
it, and a mutex is used to control the ordering of messages within
each session.

An MDS request may generate two responses.  The first indicates the
operation was a success and returns any result.  A second reply is
sent when the operation commits to disk.  Note that locking on the MDS
ensures that the results of updates are visible only to the updating
client before the operation commits.  Requests are linked to the
containing directory so that an fsync will wait for them to commit.

If an MDS fails and/or recovers, we resubmit requests as needed.  We
also reconnect existing capabilities to a recovering MDS to
reestablish that shared session state.  Old dentry leases are
invalidated.

Signed-off-by: Sage Weil <sage@newdream.net>
2009-10-06 11:31:09 -07:00