linux-toradex.git/fs/lockd, branch v3.0.16

NLM: Don't hang forever on NLM unlock requests

2011-06-15T15:24:27+00:00

If the NLM daemon is killed on the NFS server, we can currently end up
hanging forever on an 'unlock' request, instead of aborting. Basically,
if the rpcbind request fails, or the server keeps returning garbage, we
really want to quit instead of retrying.

Tested-by: Vasily Averin 
Signed-off-by: Trond Myklebust 
Cc: stable@kernel.org

NLM: Fix "kernel BUG at fs/lockd/host.c:417!" or ".../host.c:283!"

2011-01-25T20:24:47+00:00

Nick Bowler  reports:

> We were just having some NFS server troubles, and my client machine
> running 2.6.38-rc1+ (specifically, commit 2b1caf6ed7b888c95) crashed
> hard (syslog output appended to this mail).
>
> I'm not sure what the exact timeline was or how to reproduce this,
> but the server was rebooted during all this.  Since I've never seen
> this happen before, it is possibly a regression from previous kernel
> releases.  However, I recently updated my nfs-utils (on the client) to
> version 1.2.3, so that might be related as well.

  [ BUG output redacted ]

When done searching, the for_each_host loop in next_host_state() falls
through and returns the final host on the host chain without bumping
it's reference count.

Since the host's ref count is only one at that point, releasing the
host in nlm_host_rebooted() attempts to destroy the host prematurely,
and therefore hits a BUG().

Likely, the original intent of the for_each_host behavior in
next_host_state() was to handle the case when the host chain is empty.
Searching the chain and finding no suitable host to return needs to be
handled as well.

Defensively restructure next_host_state() always to return NULL when
the loop falls through.

Introduced by commit b10e30f6 "lockd: reorganize nlm_host_rebooted".

Cc: J. Bruce Fields 
Signed-off-by: Chuck Lever 
Signed-off-by: Trond Myklebust

lockd: double unlock in next_host_state()

2011-01-04T18:10:37+00:00

We unlock again after we goto out.

Signed-off-by: Dan Carpenter 
Signed-off-by: Trond Myklebust

lockd: Remove src_sap and src_len from nlm_lookup_host_info struct

2010-12-16T17:37:27+00:00

Clean up.

The contents of the src_sap field is not used in nlm_alloc_host().

Signed-off-by: Chuck Lever 
Signed-off-by: Trond Myklebust

lockd: Remove nlm_lookup_host()

2010-12-16T17:37:27+00:00

Clean up.

Remove the now unused helper nlm_lookup_host().

Signed-off-by: Chuck Lever 
Signed-off-by: Trond Myklebust

lockd: Make nrhosts an unsigned long

2010-12-16T17:37:27+00:00

Clean up.

Signed-off-by: Chuck Lever 
Signed-off-by: Trond Myklebust

lockd: Rename nlm_hosts

2010-12-16T17:37:27+00:00

Clean up.

nlm_hosts now contains only server-side entries.  Rename it to match
convention of client side cache.

Signed-off-by: Chuck Lever 
Signed-off-by: Trond Myklebust

lockd: Clean up nlmsvc_lookup_host()

2010-12-16T17:37:26+00:00

Clean up.

Change nlmsvc_lookup_host() to be purpose-built for server-side
nlm_host management.  This replaces the generic nlm_lookup_host()
helper function, just like on the client side.  The lookup logic is
specialized for server host lookups.

The server side cache also gets its own specialized equivalent of the
nlm_release_host() function.

Signed-off-by: Chuck Lever 
Signed-off-by: Trond Myklebust

lockd: Create client-side nlm_host cache

2010-12-16T17:37:26+00:00

NFS clients don't need the garbage collection processing that is
performed on nlm_host structures.  The client picks up an nlm_host at
mount time and holds a reference to it until the file system is
unmounted.

Servers, on the other hand, don't have a precise way to tell when an
nlm_host is no longer being used, so zero refcount nlm_host entries
are left to expire in the cache after a time.

Basically there's nothing holding a reference to an nlm_host between
individual server-side NLM requests, but we can't afford the expense
of recreating them for every new NLM request from a client.  The
nlm_host cache adds some lifetime hysteresis to entries in the cache
so the next time a particular nlm_host is needed, it's likely to be
discovered by a lookup rather than created from whole cloth.

With the new implementation, client nlm_host cache items are no longer
garbage collected, and are destroyed directly by a new release
function specialized for client entries, nlmclnt_release_host().  They
are cached in their own data structure, and have their own lookup
logic, simplified and specialized for client nlm_host entries.

However, the client nlm_host cache still shares reboot recovery logic
with the server nlm_host cache.  The NSM "peer rebooted" downcall for
clients and servers still come through the same RPC call.  This is a
legacy formal API that would be difficult to alter, and besides, the
user space NSM implementation can't tell the difference between peers
that are clients or servers.

For this reason, the client cache continues to share the
nlm_host_mutex (and reboot recovery logic) with the server cache.

Signed-off-by: Chuck Lever 
Signed-off-by: Trond Myklebust

lockd: Split nlm_release_call()

2010-12-16T17:37:26+00:00

The nlm_release_call() function is invoked from both the server and
the client side.  We're about to introduce a distinct server- and
client-side nlm_release_host(), so nlm_release_call() must first be
split into a client-side and a server-side version.

Signed-off-by: Chuck Lever 
Signed-off-by: Trond Myklebust