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path: root/fs/nfs/delegation.c
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2018-06-14NFS: Fix an rcu deadlock in nfs_delegation_find_inode()Anna Schumaker
I was able to reproduce this pretty regularily using xfstests generic/013 on NFS v4.0. Reported-by: Ross Zwisler <Ross.Zwisler@linux.intel.com> Fixes: 6c342655022d (NFSv4: Return NFS4ERR_DELAY when a delegation recall fails due to igrab()) Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2018-06-08NFSv4: Return NFS4ERR_DELAY when a delegation recall fails due to igrab()Trond Myklebust
If the attempt to recall the delegation fails because the inode is in the process of being evicted from cache, then use NFS4ERR_DELAY to ask the server to retry later. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2018-06-04NFSv4: Ensure the inode is clean when we set a delegationTrond Myklebust
If there are attributes that are still invalid when we set a delegation, then we need to set the NFS_INO_REVAL_FORCED flag. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2018-05-31NFS: Avoid quadratic search when freeing delegations.NeilBrown
There are three places that walk all delegation for an nfs_client and restart whenever they find something interesting - potentially resulting in a quadratic search: If there are 10,000 uninteresting delegations followed by 10,000 interesting one, then the code skips over 100,000,000 delegations, which can take a noticeable amount of time. Of these nfs_delegation_reap_unclaimed() and nfs_reap_expired_delegations() are only called during unusual events: a server reboots or reports expired delegations, probably due to a network partition. Optimizing these is not particularly important. The third, nfs_client_return_marked_delegations(), is called periodically via nfs_expire_unreferenced_delegations(). It could cause periodic problems on a busy server. New delegations are added to the end of the list, so if there are 10,000 open files with delegations, and 10,000 more recently opened files that received delegations but are now closed, then nfs_client_return_marked_delegations() can take seconds to skip over the 10,000 open files 10,000 times. That is a waste of time. The avoid this waste a place-holder (an inode) is kept when locks are dropped, so that the place can usually be found again after taking rcu_readlock(). This place holder ensure that we find the right starting point in the list of nfs_servers, and makes is probable that we find the right starting point in the list of delegations. We might need to occasionally restart at the head of that list. It might be possible that the place_holder inode could lose its delegation separately, and then get a new one using the same (freed and then reallocated) 'struct nfs_delegation'. Were this to happen, the new delegation would be at the end of the list and we would miss returning some other delegations. This would have the effect of unnecessarily delaying the return of some unused delegations until the next time this function is called - typically 90 seconds later. As this is not a correctness issue and is vanishingly unlikely to happen, it does not seem worth addressing. Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2018-05-31NFS: use cond_resched() when restarting walk of delegation list.NeilBrown
In three places we walk the list of delegations for an nfs_client until an interesting one is found, then we act of that delegation and restart the walk. New delegations are added to the end of a list and the interesting delegations are usually old, so in many case we won't repeat a long walk over and over again, but it is possible - particularly if the first server in the list has a large number of uninteresting delegations. In each cache the work done on interesting delegations will often complete without sleeping, so this could loop many times without giving up the CPU. So add a cond_resched() at an appropriate point to avoid hogging the CPU for too long. Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2018-05-31NFS: slight optimization for walking list for delegationsNeilBrown
There are 3 places where we walk the list of delegations for an nfs_client. In each case there are two nested loops, one for nfs_servers and one for nfs_delegations. When we find an interesting delegation we try to get an active reference to the server. If that fails, it is pointless to continue to look at the other delegation for the server as we will never be able to get an active reference. So instead of continuing in the inner loop, break out and continue in the outer loop. Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2018-04-10NFSv4: Fix the nfs_inode_set_delegation() argumentsTrond Myklebust
Neither nfs_inode_set_delegation() nor nfs_inode_reclaim_delegation() are generic code. They have no business delving into NFSv4 OPEN xdr structures, so let's replace the "struct nfs_openres" parameter. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-04-10NFSv4: Don't return the delegation when not needed by NFSv4.x (x>0)Trond Myklebust
Starting with NFSv4.1, the server is able to deduce the client id from the SEQUENCE op which means it can always figure out whether or not the client is holding a delegation on a file that is being changed. For that reason, RFC5661 does not require a delegation to be unconditionally recalled on operations such as SETATTR, RENAME, or REMOVE. Note that for now, we continue to return READ delegations since that is still expected by the Linux knfsd server. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-01-29nfs: convert to new i_version APIJeff Layton
For NFS, we just use the "raw" API since the i_version is mostly managed by the server. The exception there is when the client holds a write delegation, but we only need to bump it once there anyway to handle CB_GETATTR. Tested-by: Krzysztof Kozlowski <krzk@kernel.org> Signed-off-by: Jeff Layton <jlayton@redhat.com>
2017-11-17NFSv4: Retry CLOSE and DELEGRETURN on NFS4ERR_OLD_STATEID.Trond Myklebust
If we're racing with an OPEN, then retry the operation instead of declaring it a success. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> [Andrew W Elble: Fix a typo in nfs4_refresh_open_stateid] Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2017-08-15NFS: Use an atomic_long_t to count the number of requestsTrond Myklebust
Rather than forcing us to take the inode->i_lock just in order to bump the number. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2016-12-01NFSv4: Optimise away forced revalidation when we know the attributes are OKTrond Myklebust
The NFS_INO_REVAL_FORCED flag needs to be set if we just got a delegation, and we see that there might still be some ambiguity as to whether or not our attribute or data cache are valid. In practice, this means that a call to nfs_check_inode_attributes() will have noticed a discrepancy between cached attributes and measured ones, so let's move the setting of NFS_INO_REVAL_FORCED to there. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2016-09-27NFS: Always call nfs_inode_find_state_and_recover() when revoking a delegationTrond Myklebust
Don't rely on nfs_inode_detach_delegation() succeeding. That can race... Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Tested-by: Oleg Drokin <green@linuxhacker.ru> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2016-09-27NFSv4: Fix a race in nfs_inode_reclaim_delegation()Trond Myklebust
If we race with a delegreturn before taking the spin lock, we currently end up dropping the delegation stateid. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Tested-by: Oleg Drokin <green@linuxhacker.ru> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2016-09-27NFSv4: nfs_inode_find_state_and_recover() should check all stateidsTrond Myklebust
Modify the helper nfs_inode_find_state_and_recover() so that it can check all open/lock/delegation state trackers on that inode for whether or not they need are affected by a revoked stateid error. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Tested-by: Oleg Drokin <green@linuxhacker.ru> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2016-09-27NFSv4: Ensure we don't re-test revoked and freed stateidsTrond Myklebust
This fixes a potential infinite loop in nfs_reap_expired_delegations. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Tested-by: Oleg Drokin <green@linuxhacker.ru> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2016-09-27NFSv4.1: Deal with server reboots during delegation expiration recoveryTrond Myklebust
Ensure that if the server reboots while we're testing and recovering from revoked delegations, we exit to allow the state manager to handle matters. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Tested-by: Oleg Drokin <green@linuxhacker.ru> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2016-09-27NFSv4.1: Test delegation stateids when server declares "some state revoked"Trond Myklebust
According to RFC5661, if any of the SEQUENCE status bits SEQ4_STATUS_EXPIRED_ALL_STATE_REVOKED, SEQ4_STATUS_EXPIRED_SOME_STATE_REVOKED, SEQ4_STATUS_ADMIN_STATE_REVOKED, or SEQ4_STATUS_RECALLABLE_STATE_REVOKED are set, then we need to use TEST_STATEID to figure out which stateids have been revoked, so we can acknowledge the loss of state using FREE_STATEID. While we already do this for open and lock state, we have not been doing so for all the delegations. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Tested-by: Oleg Drokin <green@linuxhacker.ru> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2016-09-27NFSv4.x: Allow callers of nfs_remove_bad_delegation() to specify a stateidTrond Myklebust
Allow the callers of nfs_remove_bad_delegation() to specify the stateid that needs to be marked as bad. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Tested-by: Oleg Drokin <green@linuxhacker.ru> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2016-09-27NFSv4: nfs4_copy_delegation_stateid() must fail if the delegation is invalidTrond Myklebust
We must not allow the use of delegations that have been revoked or are being returned. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Fixes: 869f9dfa4d6d ("NFSv4: Fix races between nfs_remove_bad_delegation()...") Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Cc: stable@vger.kernel.org # v3.19+ Tested-by: Oleg Drokin <green@linuxhacker.ru> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2016-09-27NFSv4: Don't report revoked delegations as valid in nfs_have_delegation()Trond Myklebust
If the delegation is revoked, then it can't be used for caching. Fixes: 869f9dfa4d6d ("NFSv4: Fix races between nfs_remove_bad_delegation()...") Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Cc: stable@vger.kernel.org # v3.19+ Tested-by: Oleg Drokin <green@linuxhacker.ru> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2016-05-17NFSv4: Use the right stateid for delegations in setattr, read and writeTrond Myklebust
When we're using a delegation to represent our open state, we should ensure that we use the stateid that was used to create that delegation. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2015-10-08NFSv4: Don't use synchronous delegation recall in exception handlingTrond Myklebust
The code needs to be able to work from inside an asynchronous context. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-09-20NFSv4: Recovery of recalled read delegations is brokenTrond Myklebust
When a read delegation is being recalled, and we're reclaiming the cached opens, we need to make sure that we only reclaim read-only modes. A previous attempt to do this, relied on retrieving the delegation type from the nfs4_opendata structure. Unfortunately, as Kinglong pointed out, this field can only be set when performing reboot recovery. Furthermore, if we call nfs4_open_recover(), then we end up clobbering the state->flags for all modes that we're not recovering... The fix is to have the delegation recall code pass this information to the recovery call, and then refactor the recovery code so that nfs4_open_delegation_recall() does not need to call nfs4_open_recover(). Reported-by: Kinglong Mee <kinglongmee@gmail.com> Fixes: 39f897fdbd46 ("NFSv4: When returning a delegation, don't...") Tested-by: Kinglong Mee <kinglongmee@gmail.com> Cc: NeilBrown <neilb@suse.com> Cc: stable@vger.kernel.org # v4.2+ Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-09-07NFSv4: Respect the server imposed limit on how many changes we may cacheTrond Myklebust
The NFSv4 delegation spec allows the server to tell a client to limit how much data it cache after the file is closed. In return, the server guarantees enough free space to avoid ENOSPC situations, etc. Prior to this patch, we assumed we could always cache aggressively after close. Unfortunately, this causes problems with servers that set the limit to 0 and therefore do not offer any ENOSPC guarantees. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-09-07NFSv4: Express delegation limit in units of pagesTrond Myklebust
Since we're tracking modifications to the page cache on a per-page basis, it makes sense to express the limit to how much we may cache in units of pages. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-04-23Merge branch 'bugfixes'Trond Myklebust
* bugfixes: NFSv4: Return delegations synchronously in evict_inode SUNRPC: Fix a regression when reconnecting NFS: remount with security change should return EINVAL nfs: do not export discarded symbols NFSv4.1: don't export static symbol
2015-03-27NFSv4: Return delegations synchronously in evict_inodeTrond Myklebust
Kinglong Mee reports that asynchronous delegations are being killed by the call to rpc_shutdown_client() when unmounting. This can lead to state leakage on the server until the client lease expires. Reported-by: Kinglong Mee <kinglongmee@gmail.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-03-12NFSv4: Append delegations to the per-client list instead of prependingTrond Myklebust
Do so on the assumption that for most use cases, that list will turn into a more or less LRU-ordered list, and so the list traversals in nfs_client_return_marked_delegations() are likely to be shorter before hitting a candidate to return. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-03-02NFSv4: Ensure we skip delegations that are already being returnedTrond Myklebust
In nfs_client_return_marked_delegations() and nfs_delegation_reap_unclaimed() we want to optimise the loop traversal by skipping delegations that are already in the process of being returned. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-03-02NFSv4: Pin the superblock while we're returning the delegationTrond Myklebust
This patch ensures that the superblock doesn't go ahead and disappear underneath us while the state manager thread is returning delegations. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-03-02NFSv4: Ensure we honour NFS_DELEGATION_RETURNING in nfs_inode_set_delegation()Trond Myklebust
Ensure that nfs_inode_set_delegation() doesn't inadvertently detach a delegation that is already in the process of being returned. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-03-02NFSv4: Ensure that we don't reap a delegation that is being returnedTrond Myklebust
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-03-01NFSv4: Don't call put_rpccred() under the rcu_read_lock()Trond Myklebust
put_rpccred() can sleep. Fixes: 8f649c3762547 ("NFSv4: Fix the locking in nfs_inode_reclaim_delegation()") Cc: stable@vger.kernel.org # 2.6.35+ Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-02-18Merge branch 'cleanups'Trond Myklebust
Merge cleanups requested by Linus. * cleanups: (3 commits) pnfs: Refactor the *_layout_mark_request_commit to use pnfs_layout_mark_request_commit nfs: Can call nfs_clear_page_commit() instead nfs: Provide and use helper functions for marking a page as unstable
2015-02-13NFSv4: Kill unused nfs_inode->delegation_state fieldTrond Myklebust
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-02-11Merge tag 'nfs-for-3.20-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfsLinus Torvalds
Pull NFS client updates from Trond Myklebust: "Highlights incluse: Features: - Removing the forced serialisation of open()/close() calls in NFSv4.x (x>0) makes for a significant performance improvement in metadata intensive workloads. - Full support for the pNFS "flexible files" layout type - Further RPC/RDMA client improvements from Chuck Bugfixes: - Stable fix: NFSv4.1 backchannel calls blocking operations with !TASK_RUNNING - Stable fix: pnfs_generic_pg_init_read/write can be called with lseg == NULL - Stable fix: Fix an Oopsable condition when nsm_mon_unmon is called as part of the namespace cleanup, - Stable fix: Ensure we reference the inode for return-on-close in delegreturn - Use SO_REUSEPORT to ensure that NFSv3 TCP connections can rebind to the same source address/port combination during a disconnect/ reconnect event. This is a requirement imposed by most NFSv3 server duplicate reply cache implementations. Optimisations: - Ask for no NFSv4.1 delegations on OPEN if using O_DIRECT Other: - Add Anna Schumaker as co-maintainer for the NFS client" * tag 'nfs-for-3.20-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (119 commits) SUNRPC: Cleanup to remove xs_tcp_close() pnfs: delete an unintended goto pnfs/flexfiles: Do not dprintk after the free SUNRPC: Fix stupid typo in xs_sock_set_reuseport SUNRPC: Define xs_tcp_fin_timeout only if CONFIG_SUNRPC_DEBUG SUNRPC: Handle connection reset more efficiently. SUNRPC: Remove the redundant XPRT_CONNECTION_CLOSE flag SUNRPC: Make xs_tcp_close() do a socket shutdown rather than a sock_release SUNRPC: Ensure xs_tcp_shutdown() requests a full close of the connection SUNRPC: Cleanup to remove remaining uses of XPRT_CONNECTION_ABORT SUNRPC: Remove TCP socket linger code SUNRPC: Remove TCP client connection reset hack SUNRPC: TCP/UDP always close the old socket before reconnecting SUNRPC: Add helpers to prevent socket create from racing SUNRPC: Ensure xs_reset_transport() resets the close connection flags SUNRPC: Do not clear the source port in xs_reset_transport SUNRPC: Handle EADDRINUSE on connect SUNRPC: Set SO_REUSEPORT socket option for TCP connections NFSv4.1: Fix pnfs_put_lseg races NFSv4.1: pnfs_send_layoutreturn should use GFP_NOFS ...
2015-01-24NFSv4: Deal with atomic upgrades of an existing delegationTrond Myklebust
Ensure that we deal correctly with the case where the server sends us a newer instance of the same delegation. If the stateids match, but the sequence numbers differ, then treat the new delegation as if it were an atomic upgrade. Signed-off-by: Trond Myklebust <Trond.Myklebust@primarydata.com>
2015-01-16locks: add a dedicated spinlock to protect i_flctx listsJeff Layton
We can now add a dedicated spinlock without expanding struct inode. Change to using that to protect the various i_flctx lists. Signed-off-by: Jeff Layton <jlayton@primarydata.com> Acked-by: Christoph Hellwig <hch@lst.de>
2015-01-16locks: convert posix locks to file_lock_contextJeff Layton
Signed-off-by: Jeff Layton <jlayton@primarydata.com> Acked-by: Christoph Hellwig <hch@lst.de>
2015-01-16locks: move flock locks to file_lock_contextJeff Layton
Signed-off-by: Jeff Layton <jlayton@primarydata.com> Acked-by: Christoph Hellwig <hch@lst.de>
2014-11-12NFS: Don't try to reclaim delegation open state if recovery failedTrond Myklebust
If state recovery failed, then we should not attempt to reclaim delegated state. http://lkml.kernel.org/r/CAN-5tyHwG=Cn2Q9KsHWadewjpTTy_K26ee+UnSvHvG4192p-Xw@mail.gmail.com Cc: stable@vger.kernel.org Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-11-12NFSv4: Fix races between nfs_remove_bad_delegation() and delegation returnTrond Myklebust
Any attempt to call nfs_remove_bad_delegation() while a delegation is being returned is currently a no-op. This means that we can end up looping forever in nfs_end_delegation_return() if something causes the delegation to be revoked. This patch adds a mechanism whereby the state recovery code can communicate to the delegation return code that the delegation is no longer valid and that it should not be used when reclaiming state. It also changes the return value for nfs4_handle_delegation_recall_error() to ensure that nfs_end_delegation_return() does not reattempt the lock reclaim before state recovery is done. http://lkml.kernel.org/r/CAN-5tyHwG=Cn2Q9KsHWadewjpTTy_K26ee+UnSvHvG4192p-Xw@mail.gmail.com Cc: stable@vger.kernel.org Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-07-12nfs4: add nfs4_check_delegationPeng Tao
Signed-off-by: Peng Tao <tao.peng@primarydata.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-03-02NFS: Fix a delegation callback raceTrond Myklebust
The clean-up in commit 36281caa839f ended up removing a NULL pointer check that is needed in order to prevent an Oops in nfs_async_inode_return_delegation(). Reported-by: "Yan, Zheng" <zheng.z.yan@intel.com> Link: http://lkml.kernel.org/r/5313E9F6.2020405@intel.com Fixes: 36281caa839f (NFSv4: Further clean-ups of delegation stateid validation) Cc: stable@vger.kernel.org # 3.4+ Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2013-08-22NFSv4: Add tracepoints for debugging delegationsTrond Myklebust
Set up tracepoints to track when delegations are set, reclaimed, returned by the client, or recalled by the server. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-06-29locks: protect most of the file_lock handling with i_lockJeff Layton
Having a global lock that protects all of this code is a clear scalability problem. Instead of doing that, move most of the code to be protected by the i_lock instead. The exceptions are the global lists that the ->fl_link sits on, and the ->fl_block list. ->fl_link is what connects these structures to the global lists, so we must ensure that we hold those locks when iterating over or updating these lists. Furthermore, sound deadlock detection requires that we hold the blocked_list state steady while checking for loops. We also must ensure that the search and update to the list are atomic. For the checking and insertion side of the blocked_list, push the acquisition of the global lock into __posix_lock_file and ensure that checking and update of the blocked_list is done without dropping the lock in between. On the removal side, when waking up blocked lock waiters, take the global lock before walking the blocked list and dequeue the waiters from the global list prior to removal from the fl_block list. With this, deadlock detection should be race free while we minimize excessive file_lock_lock thrashing. Finally, in order to avoid a lock inversion problem when handling /proc/locks output we must ensure that manipulations of the fl_block list are also protected by the file_lock_lock. Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-04-10nfs: remove unnecessary check for NULL inode->i_flock from ↵Jeff Layton
nfs_delegation_claim_locks The second check was added in commit 65b62a29 but it will never be true. Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-04-05NFSv4: Fix CB_RECALL_ANY to only return delegations that are not in useTrond Myklebust
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-04-05NFSv4: Clean up nfs_expire_all_delegationsTrond Myklebust
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>