Testing has shown that the pool->sp_lock can be a bottleneck on a busy
server. Every time data is received on a socket, the server must take
that lock in order to dequeue a thread from the sp_threads list.

Address this problem by eliminating the sp_threads list (which contains
threads that are currently idle) and replacing it with a RQ_BUSY flag in
svc_rqst. This allows us to walk the sp_all_threads list under the
rcu_read_lock and find a suitable thread for the xprt by doing a
test_and_set_bit.

Note that we do still have a potential atomicity problem however with
this approach.  We don't want svc_xprt_do_enqueue to set the
rqst->rq_xprt pointer unless a test_and_set_bit of RQ_BUSY returned
zero (which indicates that the thread was idle). But, by the time we
check that, the bit could be flipped by a waking thread.

To address this, we acquire a new per-rqst spinlock (rq_lock) and take
that before doing the test_and_set_bit. If that returns false, then we
can set rq_xprt and drop the spinlock. Then, when the thread wakes up,
it must set the bit under the same spinlock and can trust that if it was
already set then the rq_xprt is also properly set.

With this scheme, the case where we have an idle thread no longer needs
to take the highly contended pool->sp_lock at all, and that removes the
bottleneck.

That still leaves one issue: What of the case where we walk the whole
sp_all_threads list and don't find an idle thread? Because the search is
lockess, it's possible for the queueing to race with a thread that is
going to sleep. To address that, we queue the xprt and then search again.

If we find an idle thread at that point, we can't attach the xprt to it
directly since that might race with a different thread waking up and
finding it.  All we can do is wake the idle thread back up and let it
attempt to find the now-queued xprt.
Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Tested-by: NChris Worley <chris.worley@primarydata.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

In a later patch, we'll be removing some spinlocking around the socket
and thread queueing code in order to fix some contention problems. At
that point, the stats counters will no longer be protected by the
sp_lock.

Change the counters to atomic_long_t fields, except for the
"sockets_queued" counter which will still be manipulated under a
spinlock.
Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Tested-by: NChris Worley <chris.worley@primarydata.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

...also make the manipulation of sp_all_threads list use RCU-friendly
functions.
Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Tested-by: NChris Worley <chris.worley@primarydata.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Currently all svc_create callers pass in NULL for the shutdown parm,
which then gets fixed up to be svc_rpcb_cleanup if the service uses
rpcbind.

Simplify this by instead having the the only caller that requires it
(lockd) pass in svc_rpcb_cleanup and get rid of the special casing.
Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

The way that svc_wake_up works is a bit inefficient. It walks all of the
available pools for a service and either wakes up a task in each one or
sets the SP_TASK_PENDING flag in each one.

When svc_wake_up is called, there is no need to wake up more than one
thread to do this work. In practice, only lockd currently uses this
function and it's single threaded anyway. Thus, this just boils down to
doing a wake up of a thread in pool 0 or setting a single flag.

Eliminate the for loop in this function and change it to just operate on
pool 0. Also update the comments that sit above it and get rid of some
code that has been commented out for years now.
Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

In a later patch, we'll want to be able to handle this flag without
holding the sp_lock. Change this field to an unsigned long flags
field, and declare a new flag in it that can be managed with atomic
bitops.
Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

There are a couple of holes in the svc_rqst field on x86_64. Move the
rq_cachetype to a different location to eliminate both of them.
Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

In a later patch, we're going to need some atomic bit flags. Since that
field will need to be an unsigned long, we mitigate that space
consumption by migrating some other bitflags to the new field. Start
with the rq_secure flag.
Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Mainly what I need is 860a0d9e "sunrpc: add some tracepoints in
svc_rqst handling functions", which subsequent server rpc patches from
jlayton depend on.  I'm merging this later tag on the assumption that's
more likely to be a tested and stable point.

My static checker complains that if "len == remaining" then it means we
have truncated the last character off the version string.

The intent of the code is that we print as many versions as we can
without truncating a version.  Then we put a newline at the end.  If the
newline can't fit we return -EINVAL.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Currently, it leaks when the allocation fails.
Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

All it does is indicate whether a xprt has already been deleted from
a list or not, which is unnecessary since we use list_del_init and it's
always set and checked under the sv_lock anyway.
Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Add a new directory heirarchy under the debugfs sunrpc/ directory:

    sunrpc/
        rpc_xprt/
            <xprt id>/

Within that directory, we can put files that give info about the
xprts. We do have the (minor) problem that there is no succinct,
unique identifier for rpc_xprts. So we generate them synthetically
with a static atomic_t counter.

For now, this directory just holds an "info" file, but we may add
other files to it in the future.
Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

It's possible to get a dump of the RPC task queue by writing a value to
/proc/sys/sunrpc/rpc_debug. If you write any value to that file, you get
a dump of the RPC client task list into the log buffer. This is a rather
inconvenient interface however, and makes it hard to get immediate info
about the task queue.

Add a new directory hierarchy under debugfs:

    sunrpc/
        rpc_clnt/
            <clientid>/

Within each clientid directory we create a new "tasks" file that will
dump info similar to what shows up in the log buffer, but with a few
small differences -- we avoid printing raw kernel addresses in favor of
symbolic names and the XID is also displayed.
Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Pull NFS client RDMA changes for 3.19 from Anna Schumaker:
 "NFS: Client side changes for RDMA

  These patches various bugfixes and cleanups for using NFS over RDMA, including
  better error handling and performance improvements by using pad optimization.

  Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>"

* tag 'nfs-rdma-for-3.19' of git://git.linux-nfs.org/projects/anna/nfs-rdma:
  xprtrdma: Display async errors
  xprtrdma: Enable pad optimization
  xprtrdma: Re-write rpcrdma_flush_cqs()
  xprtrdma: Refactor tasklet scheduling
  xprtrdma: unmap all FMRs during transport disconnect
  xprtrdma: Cap req_cqinit
  xprtrdma: Return an errno from rpcrdma_register_external()

Pull pull additional NFS client changes for 3.19 from Anna Schumaker:
  "NFS: Generic client side changes from Chuck

  These patches fixes for iostats and SETCLIENTID in addition to cleaning
  up the nfs4_init_callback() function.

  Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>"

* tag 'nfs-cel-for-3.19' of git://git.linux-nfs.org/projects/anna/nfs-rdma:
  NFS: Clean up nfs4_init_callback()
  NFS: SETCLIENTID XDR buffer sizes are incorrect
  SUNRPC: serialize iostats updates

This patch adds support for using the NFS v4.2 operation DEALLOCATE to
punch holes in a file.
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

This patch adds support for using the NFS v4.2 operation ALLOCATE to
preallocate data in a file.
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

nfs4_init_callback() is never invoked for NFS versions other than 4.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Use the correct calculation of the maximum size of a clientaddr4
when encoding and decoding SETCLIENTID operations. clientaddr4 is
defined in section 2.2.10 of RFC3530bis-31.

The usage in encode_setclientid_maxsz is missing the 4-byte length
in both strings, but is otherwise correct. decode_setclientid_maxsz
simply asks for a page of receive buffer space, which is
unnecessarily large (more than 4KB).

Note that a SETCLIENTID reply is either clientid+verifier, or
clientaddr4, depending on the returned NFS status. It doesn't
hurt to allocate enough space for both.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Occasionally mountstats reports a negative retransmission rate.
Ensure that two RPCs completing concurrently don't confuse the sums
in the transport's op_metrics array.

Since pNFS filelayout can invoke rpc_count_iostats() on another
transport from xprt_release(), we can't rely on simply holding the
transport_lock in xprt_release(). There's nothing for it but hard
serialization. One spin lock per RPC operation should make this as
painless as it can be.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

An async error upcall is a hard error, and should be reported in
the system log.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

The Linux NFS/RDMA server used to reject NFSv3 WRITE requests when
pad optimization was enabled. That bug was fixed by commit
e560e3b5 ("svcrdma: Add zero padding if the client doesn't send
it").

We can now enable pad optimization on the client, which helps
performance and is supported now by both Linux and Solaris servers.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Currently rpcrdma_flush_cqs() attempts to avoid code duplication,
and simply invokes rpcrdma_recvcq_upcall and rpcrdma_sendcq_upcall.

1. rpcrdma_flush_cqs() can run concurrently with provider upcalls.
   Both flush_cqs() and the upcalls were invoking ib_poll_cq() in
   different threads using the same wc buffers (ep->rep_recv_wcs
   and ep->rep_send_wcs), added by commit 1c00dd07 ("xprtrmda:
   Reduce calls to ib_poll_cq() in completion handlers").

   During transport disconnect processing, this sometimes resulted
   in the same reply getting added to the rpcrdma_tasklets_g list
   more than once, which corrupted the list.

2. The upcall functions drain only a limited number of CQEs,
   thanks to the poll budget added by commit 8301a2c0
   ("xprtrdma: Limit work done by completion handler").

Fixes: a7bc211a ("xprtrdma: On disconnect, don't ignore ... ")
BugLink: https://bugzilla.linux-nfs.org/show_bug.cgi?id=276Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Restore the separate function that schedules the reply handling
tasklet. I need to call it from two different paths.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

When using RPCRDMA_MTHCAFMR memory registration, after a few
transport disconnect / reconnect cycles, ib_map_phys_fmr() starts to
return EINVAL because the provider has exhausted its map pool.

Make sure that all FMRs are unmapped during transport disconnect,
and that ->send_request remarshals them during an RPC retransmit.
This resets the transport's MRs to ensure that none are leaked
during a disconnect.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Recent work made FRMR registration and invalidation completions
unsignaled. This greatly reduces the adapter interrupt rate.

Every so often, however, a posted send Work Request is allowed to
signal. Otherwise, the provider's Work Queue will wrap and the
workload will hang.

The number of Work Requests that are allowed to remain unsignaled is
determined by the value of req_cqinit. Currently, this is set to the
size of the send Work Queue divided by two, minus 1.

For FRMR, the send Work Queue is the maximum number of concurrent
RPCs (currently 32) times the maximum number of Work Requests an
RPC might use (currently 7, though some adapters may need more).

For mlx4, this is 224 entries. This leaves completion signaling
disabled for 111 send Work Requests.

Some providers hold back dispatching Work Requests until a CQE is
generated.  If completions are disabled, then no CQEs are generated
for quite some time, and that can stall the Work Queue.

I've seen this occur running xfstests generic/113 over NFSv4, where
eventually, posting a FAST_REG_MR Work Request fails with -ENOMEM
because the Work Queue has overflowed. The connection is dropped
and re-established.

Cap the rep_cqinit setting so completions are not left turned off
for too long.

BugLink: https://bugzilla.linux-nfs.org/show_bug.cgi?id=269Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

The RPC/RDMA send_request method and the chunk registration code
expects an errno from the registration function. This allows
the upper layers to distinguish between a recoverable failure
(for example, temporary memory exhaustion) and a hard failure
(for example, a bug in the registration logic).
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Define and use nfs_inc_fscache_stats when plus one, which can save to
pass one parameter.
Signed-off-by: NLi RongQing <roy.qing.li@gmail.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Signed-off-by: NLi RongQing <roy.qing.li@gmail.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

The nfs_put_client() function tests whether its argument is NULL and then
returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.
Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

It's always set to the same value as CONFIG_TRACEPOINTS, so we can just
use that instead.
Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

It's always set to whatever CONFIG_SUNRPC_DEBUG is, so just use that.
Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

LOCKD_DEBUG is always the same value as CONFIG_SUNRPC_DEBUG, so we can
just use it instead.
Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

nfs4_layoutget_release() drops layout hdr refcnt. Grab the refcnt
early so that it is safe to call .release in case nfs4_alloc_pages
fails.
Signed-off-by: NPeng Tao <tao.peng@primarydata.com>
Fixes: a47970ff ("NFSv4.1: Hold reference to layout hdr in layoutget")
Cc: stable@vger.kernel.org # 3.9+
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Recent work in the pgio layer made it possible for there to be more than one
request per page. This caused a subtle change in commit behavior, because
write.c:nfs_commit_unstable_pages compares the number of *pages* waiting for
writeback against the number of requests on a commit list to choose when to
send a COMMIT in a non-blocking flush.

This is probably hard to hit in normal operation - you have to be using
rsize/wsize < PAGE_SIZE, or pnfs with lots of boundaries that are not page
aligned to have a noticeable change in behavior.
Signed-off-by: NWeston Andros Adamson <dros@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>