Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Acked-by: NChristoph Hellwig <hch@lst.de>

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: NTrond Myklebust <trond.myklebust@primarydata.com>

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to the delegation return code that the delegation is no longer valid and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: NTrond Myklebust <trond.myklebust@primarydata.com>

Signed-off-by: NPeng Tao <tao.peng@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

The clean-up in commit 36281caa ended up removing a NULL pointer check
that is needed in order to prevent an Oops in
nfs_async_inode_return_delegation().
Reported-by: N"Yan, Zheng" <zheng.z.yan@intel.com>
Link: http://lkml.kernel.org/r/5313E9F6.2020405@intel.com
Fixes: 36281caa (NFSv4: Further clean-ups of delegation stateid validation)
Cc: stable@vger.kernel.org # 3.4+
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Set up tracepoints to track when delegations are set, reclaimed,
returned by the client, or recalled by the server.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The second check was added in commit 65b62a29 but it will never be true.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

If the state manager thread is already running, we may end up
racing with it in nfs_client_return_marked_delegations. Better to
just allow the state manager thread to do the job.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Currently, if the application that holds the file open isn't doing
I/O, we may end up returning the delegation. This means that we can
no longer cache the file as aggressively, and often also that we
multiply the state that both the server and the client needs to track.

This patch adds a check for open files to the routine that scans
for delegations that are unreferenced.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Unify the error handling in nfs4_open_delegation_recall and
nfs4_lock_delegation_recall.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Add a mutex to the struct nfs4_state_owner to ensure that delegation
recall doesn't conflict with byte range lock removal.

Note that we nest the new mutex _outside_ the state manager reclaim
protection (nfsi->rwsem) in order to avoid deadlocks.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

If the server reboots while we are converting a delegation into
OPEN/LOCK stateids as part of a delegation return, the current code
will simply exit with an error. This causes us to lose both
delegation state and locking state (i.e. locking atomicity).

Deal with this by exposing the delegation stateid during delegation
return, so that we can recover the delegation, and then resume
open/lock recovery.

Note that not having to hold the nfs_inode->rwsem across the
calls to nfs_delegation_claim_opens() also fixes a deadlock against
the NFSv4.1 reboot recovery code.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Delegations are a v4 feature, so push return_delegation out of the
generic client by creating a new rpc_op and renaming the old function to
be in the nfs v4 "namespace"
Signed-off-by: NBryan Schumaker <bjschuma@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Delegations are a v4 feature, so push them out of the generic code.
Signed-off-by: NBryan Schumaker <bjschuma@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

I can use this function to return delegations and unset the pnfs layout
driver rather than continuing to do these things in the generic client.
With this change, we no longer need an nfs4_kill_super().
Signed-off-by: NBryan Schumaker <bjschuma@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Since even filemap_flush() needs to lock pages that are dirty, we
cannot risk calling it from the state manager context. Therefore,
we need to move the call to filemap_flush() to
nfs_async_inode_return_delegation().
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

The assumption is that if you are in a situation where you need to
return the delegation, then you should probably stop caching the
data anyway.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Fix a number of "warning: symbol 'foo' was not declared. Should it be
static?" conditions.

Fix 2 cases of "warning: Using plain integer as NULL pointer"

fs/nfs/delegation.c:263:31: warning: restricted fmode_t degrades to integer
  - We want to allow upgrades to a WRITE delegation, but should otherwise
    consider servers that hand out duplicate delegations to be borken.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

When the NFSv4.0 server tells us that it can no-longer talk to us
on the callback channel, we should attempt a new SETCLIENTID in
order to re-transmit the callback channel information.

Note that as long as we do not change the boot verifier, this is
a safe procedure; the server is required to keep our state.

Also move the function nfs_handle_cb_pathdown to fs/nfs/nfs4state.c,
and change the name in order to mark it as being specific to NFSv4.0.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

The server will just return an NFS4ERR_OPENMODE anyway.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Handle DS READ and WRITE stateid errors by recovering the stateid on the MDS.

NFS4ERR_OLD_STATEID is ignored as the client always sends a
state sequenceid of zero for DS READ and WRITE stateids.
Signed-off-by: NAndy Adamson <andros@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Change the name to reflect what we're really doing: testing two
stateids for whether or not they match according the the rules in
RFC3530 and RFC5661.
Move the code from callback_proc.c to nfs4proc.c
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

nfs41_validate_delegation_stateid is broken if we supply a stateid with
a non-zero sequence id. Instead of trying to match the sequence id,
the function assumes that we always want to error. While this is
true for a delegation callback, it is not true in general.

Also fix a typo in nfs4_callback_recall.
Reported-by: NAndy Adamson <andros@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

If we know that the delegation stateid is bad or revoked, we need to
remove that delegation as soon as possible, and then mark all the
stateids that relied on that delegation for recovery. We cannot use
the delegation as part of the recovery process.

Also note that NFSv4.1 uses a different error code (NFS4ERR_DELEG_REVOKED)
to indicate that the delegation was revoked.

Finally, ensure that setlk() and setattr() can both recover safely from
a revoked delegation.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@vger.kernel.org

Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

nfs_mark_return_delegation() is usually called without any locking, and
so it is not safe to dereference delegation->inode. Since the inode is
only used to discover the nfs_client anyway, it makes more sense to
have the callers pass a valid pointer to the nfs_server as a parameter.
Reported-by: NIan Kent <raven@themaw.net>
Cc: stable@kernel.org
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

The rcu callback nfs_free_delegation_callback() just calls a kfree(),
so we use kfree_rcu() instead of the call_rcu(nfs_free_delegation_callback).
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

There is no reason to be freeing the delegation cred in the rcu callback,
and doing so is resulting in a lockdep complaint that rpc_credcache_lock
is being called from both softirq and non-softirq contexts.
Reported-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@kernel.org

Delegations are per-inode, not per-nfs_client.  When a server file
system is migrated, delegations on the client must be moved from the
source to the destination nfs_server.  Make it easier to manage a
mount point's delegation list across a migration event by moving the
list to the nfs_server struct.

Clean up: I added documenting comments to public functions I changed
in this patch.  For consistency I added comments to all the other
public functions in fs/nfs/delegation.c.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Clean up:  Refactor code that takes clp->cl_lock and calls
nfs_detach_delegations_locked() into its own function.

While we're changing the call sites, get rid of the second parameter
and the logic in nfs_detach_delegations_locked() that uses it, since
callers always set that parameter of nfs_detach_delegations_locked()
to NULL.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This prepares the removal of the big kernel lock from the
file locking code. We still use the BKL as long as fs/lockd
uses it and ceph might sleep, but we can flip the definition
to a private spinlock as soon as that's done.
All users outside of fs/lockd get converted to use
lock_flocks() instead of lock_kernel() where appropriate.

Based on an earlier patch to use a spinlock from Matthew
Wilcox, who has attempted this a few times before, the
earliest patch from over 10 years ago turned it into
a semaphore, which ended up being slower than the BKL
and was subsequently reverted.

Someone should do some serious performance testing when
this becomes a spinlock, since this has caused problems
before. Using a spinlock should be at least as good
as the BKL in theory, but who knows...
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NMatthew Wilcox <willy@linux.intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Sage Weil <sage@newdream.net>
Cc: linux-kernel@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org

There is no need to flush out writes before calling nfs_wb_all().
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

We do not want to have the state recovery thread kick off and wait for a
memory reclaim, since that may deadlock when the writebacks end up
waiting for the state recovery thread to complete.

The safe thing is therefore to use GFP_NOFS in all open, close,
delegation return, lock, etc. operations that may be called by the
state recovery thread.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Fix a number of RCU issues in the NFSv4 delegation code.

 (1) delegation->cred doesn't need to be RCU protected as it's essentially an
     invariant refcounted structure.

     By the time we get to nfs_free_delegation(), the delegation is being
     released, so no one else should be attempting to use the saved
     credentials, and they can be cleared.

     However, since the list of delegations could still be under traversal at
     this point by such as nfs_client_return_marked_delegations(), the cred
     should be released in nfs_do_free_delegation() rather than in
     nfs_free_delegation().  Simply using rcu_assign_pointer() to clear it is
     insufficient as that doesn't stop the cred from being destroyed, and nor
     does calling put_rpccred() after call_rcu(), given that the latter is
     asynchronous.

 (2) nfs_detach_delegation_locked() and nfs_inode_set_delegation() should use
     rcu_derefence_protected() because they can only be called if
     nfs_client::cl_lock is held, and that guards against anyone changing
     nfsi->delegation under it.  Furthermore, the barrier imposed by
     rcu_dereference() is superfluous, given that the spin_lock() is also a
     barrier.

 (3) nfs_detach_delegation_locked() is now passed a pointer to the nfs_client
     struct so that it can issue lockdep advice based on clp->cl_lock for (2).

 (4) nfs_inode_return_delegation_noreclaim() and nfs_inode_return_delegation()
     should use rcu_access_pointer() outside the spinlocked region as they
     merely examine the pointer and don't follow it, thus rendering unnecessary
     the need to impose a partial ordering over the one item of interest.

     These result in an RCU warning like the following:

[ INFO: suspicious rcu_dereference_check() usage. ]
---------------------------------------------------
fs/nfs/delegation.c:332 invoked rcu_dereference_check() without protection!

other info that might help us debug this:

rcu_scheduler_active = 1, debug_locks = 0
2 locks held by mount.nfs4/2281:
 #0:  (&type->s_umount_key#34){+.+...}, at: [<ffffffff810b25b4>] deactivate_super+0x60/0x80
 #1:  (iprune_sem){+.+...}, at: [<ffffffff810c332a>] invalidate_inodes+0x39/0x13a

stack backtrace:
Pid: 2281, comm: mount.nfs4 Not tainted 2.6.34-rc1-cachefs #110
Call Trace:
 [<ffffffff8105149f>] lockdep_rcu_dereference+0xaa/0xb2
 [<ffffffffa00b4591>] nfs_inode_return_delegation_noreclaim+0x5b/0xa0 [nfs]
 [<ffffffffa0095d63>] nfs4_clear_inode+0x11/0x1e [nfs]
 [<ffffffff810c2d92>] clear_inode+0x9e/0xf8
 [<ffffffff810c3028>] dispose_list+0x67/0x10e
 [<ffffffff810c340d>] invalidate_inodes+0x11c/0x13a
 [<ffffffff810b1dc1>] generic_shutdown_super+0x42/0xf4
 [<ffffffff810b1ebe>] kill_anon_super+0x11/0x4f
 [<ffffffffa009893c>] nfs4_kill_super+0x3f/0x72 [nfs]
 [<ffffffff810b25bc>] deactivate_super+0x68/0x80
 [<ffffffff810c6744>] mntput_no_expire+0xbb/0xf8
 [<ffffffff810c681b>] release_mounts+0x9a/0xb0
 [<ffffffff810c689b>] put_mnt_ns+0x6a/0x79
 [<ffffffffa00983a1>] nfs_follow_remote_path+0x5a/0x146 [nfs]
 [<ffffffffa0098334>] ? nfs_do_root_mount+0x82/0x95 [nfs]
 [<ffffffffa00985a9>] nfs4_try_mount+0x75/0xaf [nfs]
 [<ffffffffa0098874>] nfs4_get_sb+0x291/0x31a [nfs]
 [<ffffffff810b2059>] vfs_kern_mount+0xb8/0x177
 [<ffffffff810b2176>] do_kern_mount+0x48/0xe8
 [<ffffffff810c810b>] do_mount+0x782/0x7f9
 [<ffffffff810c8205>] sys_mount+0x83/0xbe
 [<ffffffff81001eeb>] system_call_fastpath+0x16/0x1b

Also on:

fs/nfs/delegation.c:215 invoked rcu_dereference_check() without protection!
 [<ffffffff8105149f>] lockdep_rcu_dereference+0xaa/0xb2
 [<ffffffffa00b4223>] nfs_inode_set_delegation+0xfe/0x219 [nfs]
 [<ffffffffa00a9c6f>] nfs4_opendata_to_nfs4_state+0x2c2/0x30d [nfs]
 [<ffffffffa00aa15d>] nfs4_do_open+0x2a6/0x3a6 [nfs]
 ...

And:

fs/nfs/delegation.c:40 invoked rcu_dereference_check() without protection!
 [<ffffffff8105149f>] lockdep_rcu_dereference+0xaa/0xb2
 [<ffffffffa00b3bef>] nfs_free_delegation+0x3d/0x6e [nfs]
 [<ffffffffa00b3e71>] nfs_do_return_delegation+0x26/0x30 [nfs]
 [<ffffffffa00b406a>] __nfs_inode_return_delegation+0x1ef/0x1fe [nfs]
 [<ffffffffa00b448a>] nfs_client_return_marked_delegations+0xc9/0x124 [nfs]
 ...
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>