Commit Graph

1388 Commits

Author SHA1 Message Date
Ricardo Labiaga
180197536b nfs41: RECLAIM_COMPLETE XDR functionality
XDR encoding and decoding for RECLAIM_COMPLETE.  Implements the necessary
encoding to indicate reclaim complete for the entire client.  In the future,
it can be extended to provide reclaim complete functionality for a single
file system after migration.

Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-05 16:08:40 -05:00
Ricardo Labiaga
8b173218bd Cleanup some NFSv4 XDR decode comments
Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-05 16:08:39 -05:00
Trond Myklebust
0556d1a695 NFSv41: nfs4_reset_session must always set NFS4CLNT_SESSION_DRAINING
Otherwise we have no guarantees that other processes won't start another
RPC call while we're resetting the session.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-05 15:03:20 -05:00
Alexandros Batsakis
2597641dea nfs41: v2 fix cb_recall bug
in NFSv4.1 the seqid part of a stateid in CB_RECALL must be 0

Signed-off-by: Alexandros Batsakis <batsakis@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-05 13:48:55 -05:00
Alexandros Batsakis
0629e370dd nfs41: check SEQUENCE status flag
the server can indicate a number of error conditions by setting the
appropriate bits in the SEQUENCE operation. The client re-establishes
state with the server when it receives one of those, with the action
depending on the specific case.

Signed-off-by: Alexandros Batsakis <batsakis@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-05 13:46:14 -05:00
Alexandros Batsakis
2449ea2e19 nfs41: V2 adjust max_rqst_sz, max_resp_sz w.r.t to rsize, wsize
The v4.1 client should take into account the desired rsize, wsize when
negotiating the max size in CREATE_SESSION. Accordingly, it should use
rsize, wsize that are smaller than the session negotiated values.

Signed-off-by: Alexandros Batsakis <batsakis@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-05 13:36:55 -05:00
Alexandros Batsakis
7b183d0d43 nfs41: remove server-only EXCHGID4_FLAG_CONFIRMED_R flag from exchange_id
Signed-off-by: Alexandros Batsakis <batsakis@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-05 13:33:25 -05:00
Alexandros Batsakis
4882ef72cd nfs41: add support for the exclusive create flags
In v4.1 the client MUST/SHOULD use the EXCLUSIVE4_1 flag instead of
EXCLUSIVE4, and GUARDED when the server supports persistent sessions.
For now (and until we support suppattr_exclcreat), we don't send any
attributes with EXCLUSIVE4_1 relying in the subsequent SETATTR as in v4.0

Signed-off-by: Alexandros Batsakis <batsakis@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-05 13:30:21 -05:00
Alexandros Batsakis
d8cb1a7ce3 nfs41: check if session exists and if it is persistent
Signed-off-by: Alexandros Batsakis <batsakis@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-05 13:29:53 -05:00
Alexandros Batsakis
31f0960778 nfs41: V2 initial support for CB_RECALL_ANY
For now the clients returns _all_ the delegations of the specificed type
it holds

Signed-off-by: Alexandros Batsakis <batsakis@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-05 13:27:02 -05:00
Alexandros Batsakis
c79571a508 nfs4: V2 return/expire delegations depending on their type
Signed-off-by: Alexandros Batsakis <batsakis@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-05 13:20:52 -05:00
Alexandros Batsakis
b4a6f4966e nfs4: minor delegation cleaning
Signed-off-by: Alexandros Batsakis <batsakis@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-05 13:19:11 -05:00
Alexandros Batsakis
07bccc2dd4 nfs41: add support for callback with RPC version number 4
The NFSv4.1 spec-29 (18.36.3) says that the server MUST use an ONC RPC
(program) version number equal to 4 in callbacks sent to the client.
For now we allow both versions 1 and 4.

Signed-off-by: Alexandros Batsakis <batsakis@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-05 13:19:01 -05:00
Andy Adamson
0b9e2d41f1 nfs41: only state manager sets NFS4CLNT_SESSION_SETUP
Replace sync and async handlers setting of the NFS4CLNT_SESSION_SETUP bit with
setting NFS4CLNT_CHECK_LEASE, and let the state manager decide to reset the session.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-04 16:02:14 -05:00
Andy Adamson
691daf3b0c nfs41: drain session cleanup
Do not wake up the next slot_tbl_waitq task in nfs4_free_slot because we
may be draining the slot. Either signal the state manager that the session
is drained (the state manager wakes up tasks) OR wake up the next task.

In nfs41_sequence_done, the slot dereference is only needed in the sequence
operation success case.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-04 15:55:39 -05:00
Andy Adamson
ea028ac925 nfs41: nfs41: fix state manager deadlock in session reset
If the session is reset during state recovery, the state manager thread can
sleep on the slot_tbl_waitq causing a deadlock.

Add a completion framework to the session.  Have the state manager thread set
a new session state (NFS4CLNT_SESSION_DRAINING) and wait for the session slot
table to drain.

Signal the state manager thread in nfs41_sequence_free_slot when the
NFS4CLNT_SESSION_DRAINING bit is set and the session is drained.

Reported-by: Trond Myklebust <trond@netapp.com>
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-04 15:55:38 -05:00
Andy Adamson
05f0d23647 nfs41: remove nfs4_recover_session
nfs4_recover_session can put rpciod to sleep. Just use nfs4_schedule_recovery.

Reported-by: Trond Myklebust <trond.myklebust@netapp.com>
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-04 15:55:37 -05:00
Andy Adamson
2628eddff1 nfs41: don't clear tk_action on success
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-04 15:55:35 -05:00
Andy Adamson
8ba9bf8e51 nfs41: fix switch in nfs4_recovery_handle_error
Do not fall through and set NFS4CLNT_SESSION_RESET bit on NFS4ERR_EXPIRED

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-04 15:55:34 -05:00
Andy Adamson
b9179237e2 nfs41: fix switch in nfs4_handle_exception
Do not fall through and call nfs4_delay on session error handling.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-04 15:55:32 -05:00
Andy Adamson
36bbe34239 nfs41: free the slot on unhandled read errors
nfs4_read_done returns zero on unhandled errors. nfs_readpage_result will
return on a negative tk_status without freeing the slot.
Call nfs4_sequence_free_slot on unhandled errors in nfs4_read_done.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-04 15:55:30 -05:00
Andy Adamson
e608e79f1b nfs41: call free slot from nfs4_restart_rpc
nfs41_sequence_free_slot can be called multiple times on SEQUENCE operation
errors.
No reason to inline nfs4_restart_rpc

Reported-by: Trond Myklebust <trond.myklebust@netapp.com>

nfs_writeback_done and nfs_readpage_retry call nfs4_restart_rpc outside the
error handler, and the slot is not freed prior to restarting in the rpc_prepare
state during session reset.

Fix this by moving the call to nfs41_sequence_free_slot from the error
path of nfs41_sequence_done into nfs4_restart_rpc, and by removing the test
for NFS4CLNT_SESSION_SETUP.
Always free slot and goto the rpc prepare state on async errors.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-04 15:55:29 -05:00
Andy Adamson
1d9ddde94a nfs41: nfs4_get_lease_time will never session reset
Make this clear by calling rpc_restart-call.
Prepare for nfs4_restart_rpc() to free slots.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-04 15:55:27 -05:00
Andy Adamson
6df08189ff nfs41: rename cl_state session SETUP bit to RESET
The bit is no longer used for session setup, only for session reset.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-04 15:55:05 -05:00
Andy Adamson
4d643d1dfa nfs41: add create session into establish_clid
Reported-by: Trond Myklebust <trond.myklebust@netapp.com>

Resetting the clientid from the state manager could result in not confirming
the clientid due to create session not being called.

Move the create session call from the NFS4CLNT_SESSION_SETUP state manager
initialize session case into the NFS4CLNT_LEASE_EXPIRED case establish_clid
call.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-04 15:52:24 -05:00
Trond Myklebust
7285f2d2ff Merge branch 'devel' into linux-next 2009-12-03 21:27:36 -05:00
NeilBrown
44ed3556ba NFS4ERR_FILE_OPEN handling in Linux/NFS
NFS4ERR_FILE_OPEN is return by the server when an operation cannot be
performed because the file is currently open and local (to the server)
semantics prohibit the operation while the file is open.
A typical case is a RENAME operation on an MS-Windows platform, which
prevents rename while the file is open.

While it is possible that such a condition is transitory, it is also
very possible that the file will be held open for an extended period
of time thus preventing the operation.

The current behaviour of Linux/NFS is to retry the operation
indefinitely.  This is not appropriate - we do not expect a rename to
take an arbitrary amount of time to complete.

Rather, and error should be returned.  The most obvious error code
would be EBUSY, which is a legal at least for 'rename' and 'unlink',
and accurately captures the reason for the error.

This patch allows a few retries until about 2 seconds have elapsed,
then returns EBUSY.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 21:26:36 -05:00
Miklos Szeredi
24e93025ee nfs: clean up sillyrenaming in nfs_rename()
The d_instantiate(new_dentry, NULL) is superfluous, the dentry is
already negative.  Rehashing this dummy dentry isn't needed either,
d_move() works fine on an unhashed target.

The re-checking for busy after a failed nfs_sillyrename() is bogus
too: new_dentry->d_count < 2 would be a bug here.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 15:58:56 -05:00
Miklos Szeredi
27226104e6 nfs: dont unhash target if renaming a directory
Move unhashing the target to after the check for existence and being a
non-directory.

If renaming a directory then the VFS already unhashes the target if it
is not busy.  If it's busy then acquiring more references during the
rename makes no difference.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 15:58:56 -05:00
Miklos Szeredi
28f79a1a69 nfs: fix comments in nfs_rename()
Comments are wrong or out of date.  In particular d_drop() doesn't
free the inode it just unhashes the dentry.  And if target is a
directory then it is not checked for being busy.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 15:58:56 -05:00
Miklos Szeredi
e48de5ec25 nfs: remove unnecessary check from nfs_rename()
VFS already checks if both source and target are directories.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 15:58:56 -05:00
Trond Myklebust
9c4c761a62 NFSv4.1: Handle NFSv4.1 session errors in the lock recovery code
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 15:58:56 -05:00
Chuck Lever
dd47f96c07 NFS: Revert default r/wsize behavior
When the "rsize=" or "wsize=" mount options are not specified,
text-based mounts have slightly different behavior than legacy binary
mounts.  Text-based mounts use the smaller of the server's maximum
and the client's maximum, but binary mounts use the smaller of the
server's _preferred_ size and the client's maximum.

This difference is actually pretty subtle.  Most servers advertise
the same value as their maximum and their preferred transfer size, so
the end result is the same in most cases.

The reason for this difference is that for text-based mounts, if
r/wsize are not specified, they are set to the largest value supported
by the client.  For legacy mounts, the values are set to zero if these
options are not specified.

nfs_server_set_fsinfo() can negotiate the transfer size defaults
correctly in any case.  There's no need to specify any particular
value as default in the text-based option parsing logic.

Note that nfs4 doesn't use nfs_server_set_fsinfo(), but the mount.nfs4
command does set rsize and wsize to 0 if the user didn't specify these
options.  So, make the same change for text-based NFSv4 mounts.

Thanks to James Pearson <james-p@moving-picture.com> for reporting and
diagnosing the problem.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 15:58:56 -05:00
Chuck Lever
d250e190fb NFS: Display compressed (shorthand) IPv6 in /proc/mounts
Recent changes to snprintf() introduced the %pI6c formatter, which can
display an IPv6 address with standard shorthanding.  Use this new
formatter when displaying IPv6 server addresses in /proc/mounts.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 15:58:56 -05:00
Jeff Layton
ee671b016f NFS: convert proto= option to use netids rather than a protoname
Solaris uses netids as values for the proto= option, so that when
someone specifies "tcp6" they get traffic over TCP + IPv6. Until
recently, this has never really been an issue for Linux since it didn't
support NFS over IPv6. The netid and the protocol name were generally
always the same (modulo any strange configuration in /etc/netconfig).

The solaris manpage documents their proto= option as:

    proto= _netid_ | rdma

This patch is intended to bring Linux closer to how the Solaris proto=
option works, by declaring a static netid mapping in the kernel and
converting the proto= and mountproto= options to follow it and display
the proper values in /proc/mounts.

Much of this functionality will need to be provided by a userspace
mount.nfs patch. Chuck Lever has a patch to change mount.nfs in
the same way. In principle, we could do *all* of this in userspace but
that would mean that the options in /proc/mounts may not match the
options used by userspace.

The alternative to the static mapping here is to add a mechanism to
upcall to userspace for netid's. I'm not opposed to that option, but
it'll probably mean more overhead (and quite a bit more code). Rather
than shoot for that at first, I figured it was probably better to
start simply.

Comments welcome.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 15:58:56 -05:00
J. Bruce Fields
d4e935bd67 The rpc server does not require that service threads take the BKL.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 15:58:33 -05:00
Trond Myklebust
1185a552e3 NFSv4: Ensure nfs4_close_context() is declared as static
Fix another 'sparse' warning in fs/nfs/nfs4proc.c

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 15:54:02 -05:00
Trond Myklebust
0a6566ecd3 NFSv4: Ensure nfs_dns_lookup() and nfs_dns_update() are declared static
Fix two 'sparse' warnings in fs/nfs/dns_resolve.c

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 15:54:01 -05:00
Trond Myklebust
b6d408ba8c NFSv4: Fix up error handling in the state manager main loop.
The nfs4_state_manager should not be looking at the error values when
deciding whether or not to loop round in order to handle a higher priority
state recovery task. It should rather be looking at the clp->cl_state.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 15:53:22 -05:00
Trond Myklebust
a9ed2e2583 NFSv4: Handle NFS4ERR_GRACE when recovering an expired lease.
If our lease expires, and the server reboots while we're recovering, we
need to be able to wait until the grace period is over.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 15:53:21 -05:00
Trond Myklebust
c8b7ae3d32 NFSv4: Ensure the state manager handles NFS4ERR_NO_GRACE correctly
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 15:53:21 -05:00
Trond Myklebust
4f7cdf18e1 NFSv4: The state manager shouldn't exit on errors that were handled
nfs4_recovery_handle_error() will correctly handle errors such as
NFS4ERR_CB_PATH_DOWN, however because they are still passed back to the
main loop in nfs4_state_manager(), they can cause the latter to exit
prematurely.

Fix this by letting nfs4_recovery_handle_error() change the error value in
cases where there is no action required by the caller.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 15:53:20 -05:00
Trond Myklebust
e345e88a77 NFSv4: Fix up the callers of nfs4_state_end_reclaim_reboot
In practice, we need to ensure that we call nfs4_state_end_reclaim_reboot
in 2 cases:

 - If we lose the lease while we were reclaiming state
OR
 - After we're done with reboot recovery

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 15:52:41 -05:00
Trond Myklebust
d18cc1fda2 NFSv4: Fix a potential state manager deadlock when returning delegations
The nfsv4 state manager could potentially deadlock inside
__nfs_inode_return_delegation() if the server reboots, so that the calls to
nfs_msync_inode() end up waiting on state recovery to complete.

Also ensure that if a server reboot or network partition causes us to have
to stop returning delegations, that NFS4CLNT_DELEGRETURN is set so that
the state manager can resume any outstanding delegation returns after it
has dealt with the state recovery situation.

Finally, ensure that the state manager doesn't wait for the DELEGRETURN
call to complete. It doesn't need to, and that too can cause a deadlock.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 08:10:17 -05:00
J. Bruce Fields
d327cf7449 Re: acl trouble after upgrading ubuntu
Subject: [PATCH] nfs: fix acl decoding

Commit 28f566942c "NFS: use dynamically
computed compound_hdr.replen for xdr_inline_pages offset" accidentally
changed the amount of space to allow for the acl reply, resulting in an
IO error on attempts to get an acl.

Reported-by: Paul Rudin <paul@rudin.co.uk>
Cc: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 08:10:17 -05:00
Trond Myklebust
96f287b0cf NFS: BKL removal from the mount code...
None of the code in nfs_umount_begin() or nfs_remount() has any BKL
dependency.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-12-03 08:09:56 -05:00
Linus Torvalds
6e80133f7f Merge git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-2.6-fscache
* git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-2.6-fscache: (31 commits)
  FS-Cache: Provide nop fscache_stat_d() if CONFIG_FSCACHE_STATS=n
  SLOW_WORK: Fix GFS2 to #include <linux/module.h> before using THIS_MODULE
  SLOW_WORK: Fix CIFS to pass THIS_MODULE to slow_work_register_user()
  CacheFiles: Don't log lookup/create failing with ENOBUFS
  CacheFiles: Catch an overly long wait for an old active object
  CacheFiles: Better showing of debugging information in active object problems
  CacheFiles: Mark parent directory locks as I_MUTEX_PARENT to keep lockdep happy
  CacheFiles: Handle truncate unlocking the page we're reading
  CacheFiles: Don't write a full page if there's only a partial page to cache
  FS-Cache: Actually requeue an object when requested
  FS-Cache: Start processing an object's operations on that object's death
  FS-Cache: Make sure FSCACHE_COOKIE_LOOKING_UP cleared on lookup failure
  FS-Cache: Add a retirement stat counter
  FS-Cache: Handle pages pending storage that get evicted under OOM conditions
  FS-Cache: Handle read request vs lookup, creation or other cache failure
  FS-Cache: Don't delete pending pages from the page-store tracking tree
  FS-Cache: Fix lock misorder in fscache_write_op()
  FS-Cache: The object-available state can't rely on the cookie to be available
  FS-Cache: Permit cache retrieval ops to be interrupted in the initial wait phase
  FS-Cache: Use radix tree preload correctly in tracking of pages to be stored
  ...
2009-11-30 13:33:48 -08:00
David Howells
201a15428b FS-Cache: Handle pages pending storage that get evicted under OOM conditions
Handle netfs pages that the vmscan algorithm wants to evict from the pagecache
under OOM conditions, but that are waiting for write to the cache.  Under these
conditions, vmscan calls the releasepage() function of the netfs, asking if a
page can be discarded.

The problem is typified by the following trace of a stuck process:

	kslowd005     D 0000000000000000     0  4253      2 0x00000080
	 ffff88001b14f370 0000000000000046 ffff880020d0d000 0000000000000007
	 0000000000000006 0000000000000001 ffff88001b14ffd8 ffff880020d0d2a8
	 000000000000ddf0 00000000000118c0 00000000000118c0 ffff880020d0d2a8
	Call Trace:
	 [<ffffffffa00782d8>] __fscache_wait_on_page_write+0x8b/0xa7 [fscache]
	 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34
	 [<ffffffffa0078240>] ? __fscache_check_page_write+0x63/0x70 [fscache]
	 [<ffffffffa00b671d>] nfs_fscache_release_page+0x4e/0xc4 [nfs]
	 [<ffffffffa00927f0>] nfs_release_page+0x3c/0x41 [nfs]
	 [<ffffffff810885d3>] try_to_release_page+0x32/0x3b
	 [<ffffffff81093203>] shrink_page_list+0x316/0x4ac
	 [<ffffffff8109372b>] shrink_inactive_list+0x392/0x67c
	 [<ffffffff813532fa>] ? __mutex_unlock_slowpath+0x100/0x10b
	 [<ffffffff81058df0>] ? trace_hardirqs_on_caller+0x10c/0x130
	 [<ffffffff8135330e>] ? mutex_unlock+0x9/0xb
	 [<ffffffff81093aa2>] shrink_list+0x8d/0x8f
	 [<ffffffff81093d1c>] shrink_zone+0x278/0x33c
	 [<ffffffff81052d6c>] ? ktime_get_ts+0xad/0xba
	 [<ffffffff81094b13>] try_to_free_pages+0x22e/0x392
	 [<ffffffff81091e24>] ? isolate_pages_global+0x0/0x212
	 [<ffffffff8108e743>] __alloc_pages_nodemask+0x3dc/0x5cf
	 [<ffffffff81089529>] grab_cache_page_write_begin+0x65/0xaa
	 [<ffffffff8110f8c0>] ext3_write_begin+0x78/0x1eb
	 [<ffffffff81089ec5>] generic_file_buffered_write+0x109/0x28c
	 [<ffffffff8103cb69>] ? current_fs_time+0x22/0x29
	 [<ffffffff8108a509>] __generic_file_aio_write+0x350/0x385
	 [<ffffffff8108a588>] ? generic_file_aio_write+0x4a/0xae
	 [<ffffffff8108a59e>] generic_file_aio_write+0x60/0xae
	 [<ffffffff810b2e82>] do_sync_write+0xe3/0x120
	 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34
	 [<ffffffff810b18e1>] ? __dentry_open+0x1a5/0x2b8
	 [<ffffffff810b1a76>] ? dentry_open+0x82/0x89
	 [<ffffffffa00e693c>] cachefiles_write_page+0x298/0x335 [cachefiles]
	 [<ffffffffa0077147>] fscache_write_op+0x178/0x2c2 [fscache]
	 [<ffffffffa0075656>] fscache_op_execute+0x7a/0xd1 [fscache]
	 [<ffffffff81082093>] slow_work_execute+0x18f/0x2d1
	 [<ffffffff8108239a>] slow_work_thread+0x1c5/0x308
	 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34
	 [<ffffffff810821d5>] ? slow_work_thread+0x0/0x308
	 [<ffffffff8104be91>] kthread+0x7a/0x82
	 [<ffffffff8100beda>] child_rip+0xa/0x20
	 [<ffffffff8100b87c>] ? restore_args+0x0/0x30
	 [<ffffffff8102ef83>] ? tg_shares_up+0x171/0x227
	 [<ffffffff8104be17>] ? kthread+0x0/0x82
	 [<ffffffff8100bed0>] ? child_rip+0x0/0x20

In the above backtrace, the following is happening:

 (1) A page storage operation is being executed by a slow-work thread
     (fscache_write_op()).

 (2) FS-Cache farms the operation out to the cache to perform
     (cachefiles_write_page()).

 (3) CacheFiles is then calling Ext3 to perform the actual write, using Ext3's
     standard write (do_sync_write()) under KERNEL_DS directly from the netfs
     page.

 (4) However, for Ext3 to perform the write, it must allocate some memory, in
     particular, it must allocate at least one page cache page into which it
     can copy the data from the netfs page.

 (5) Under OOM conditions, the memory allocator can't immediately come up with
     a page, so it uses vmscan to find something to discard
     (try_to_free_pages()).

 (6) vmscan finds a clean netfs page it might be able to discard (possibly the
     one it's trying to write out).

 (7) The netfs is called to throw the page away (nfs_release_page()) - but it's
     called with __GFP_WAIT, so the netfs decides to wait for the store to
     complete (__fscache_wait_on_page_write()).

 (8) This blocks a slow-work processing thread - possibly against itself.

The system ends up stuck because it can't write out any netfs pages to the
cache without allocating more memory.

To avoid this, we make FS-Cache cancel some writes that aren't in the middle of
actually being performed.  This means that some data won't make it into the
cache this time.  To support this, a new FS-Cache function is added
fscache_maybe_release_page() that replaces what the netfs releasepage()
functions used to do with respect to the cache.

The decisions fscache_maybe_release_page() makes are counted and displayed
through /proc/fs/fscache/stats on a line labelled "VmScan".  There are four
counters provided: "nos=N" - pages that weren't pending storage; "gon=N" -
pages that were pending storage when we first looked, but weren't by the time
we got the object lock; "bsy=N" - pages that we ignored as they were actively
being written when we looked; and "can=N" - pages that we cancelled the storage
of.

What I'd really like to do is alter the behaviour of the cancellation
heuristics, depending on how necessary it is to expel pages.  If there are
plenty of other pages that aren't waiting to be written to the cache that
could be ejected first, then it would be nice to hold up on immediate
cancellation of cache writes - but I don't see a way of doing that.

Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 18:11:35 +00:00
Trond Myklebust
96d25e5322 NFSv4: Fix a cache validation bug which causes getcwd() to return ENOENT
Changeset a65318bf3a (NFSv4: Simplify some
cache consistency post-op GETATTRs) incorrectly changed the getattr
bitmap for readdir().
This causes the readdir() function to fail to return a
fileid/inode number, which again exposed a bug in the NFS readdir code that
causes spurious ENOENT errors to appear in applications (see
http://bugzilla.kernel.org/show_bug.cgi?id=14541).

The immediate band aid is to revert the incorrect bitmap change, but more
long term, we should change the NFS readdir code to cope with the
fact that NFSv4 servers are not required to support fileids/inode numbers.

Reported-by: Daniel J Blueman <daniel.blueman@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-11-11 16:15:42 +09:00
Trond Myklebust
9a3936aac1 NFSv4: The link() operation should return any delegation on the file
Otherwise, we have to wait for the server to recall it.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-10-26 08:09:46 -04:00