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  1. 11 2月, 2008 4 次提交
    • J
      NLM: don't requeue block if it was invalidated while GRANT_MSG was in flight · c64e80d5
      由 Jeff Layton 提交于 
      It's possible for lockd to catch a SIGKILL while a GRANT_MSG callback
is in flight. If this happens we don't want lockd to insert the block
back into the nlm_blocked list.

This helps that situation, but there's still a possible race. Fixing
that will mean adding real locking for nlm_blocked.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
      c64e80d5
    • J
      NLM: don't reattempt GRANT_MSG when there is already an RPC in flight · 9706501e
      由 Jeff Layton 提交于 
      With the current scheme in nlmsvc_grant_blocked, we can end up with more
than one GRANT_MSG callback for a block in flight. Right now, we requeue
the block unconditionally so that a GRANT_MSG callback is done again in
30s. If the client is unresponsive, it can take more than 30s for the
call already in flight to time out.

There's no benefit to having more than one GRANT_MSG RPC queued up at a
time, so put it on the list with a timeout of NLM_NEVER before doing the
RPC call. If the RPC call submission fails, we requeue it with a short
timeout. If it works, then nlmsvc_grant_callback will end up requeueing
it with a shorter timeout after it completes.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
      9706501e
    • J
      NLM: have server-side RPC clients default to soft RPC tasks · 90bd17c8
      由 Jeff Layton 提交于 
      Now that it no longer does an RPC ping, lockd always ends up queueing
an RPC task for the GRANT_MSG callback. But, it also requeues the block
for later attempts. Since these are hard RPC tasks, if the client we're
calling back goes unresponsive the GRANT_MSG callbacks can stack up in
the RPC queue.

Fix this by making server-side RPC clients default to soft RPC tasks.
lockd requeues the block anyway, so this should be OK.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
      90bd17c8
    • J
      NLM: set RPC_CLNT_CREATE_NOPING for NLM RPC clients · 031fd3aa
      由 Jeff Layton 提交于 
      It's currently possible for an unresponsive NLM client to completely
lock up a server's lockd. The scenario is something like this:

1) client1 (or a process on the server) takes a lock on a file
2) client2 tries to take a blocking lock on the same file and
   awaits the callback
3) client2 goes unresponsive (plug pulled, network partition, etc)
4) client1 releases the lock

...at that point the server's lockd will try to queue up a GRANT_MSG
callback for client2, but first it requeues the block with a timeout of
30s. nlm_async_call will attempt to bind the RPC client to client2 and
will call rpc_ping. rpc_ping entails a sync RPC call and if client2 is
unresponsive it will take around 60s for that to time out. Once it times
out, it's already time to retry the block and the whole process repeats.

Once in this situation, nlmsvc_retry_blocked will never return until
the host starts responding again. lockd won't service new calls.

Fix this by skipping the RPC ping on NLM RPC clients. This makes
nlm_async_call return quickly when called.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
      031fd3aa
  3. 06 2月, 2008 36 次提交