Micro-optimization: Save eight bytes in a frequently allocated
structure.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Micro-optimization: Save eight bytes in a frequently allocated
structure.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

ia->ri_id is replaced during a reconnect. The connect_worker runs
with the transport send lock held to prevent ri_id from being
dereferenced by the send_request path during this process.

Currently, however, there is no guarantee that ia->ri_id is stable
in the MR recycling worker, which operates in the background and is
not serialized with the connect_worker in any way.

But now that Local_Inv completions are being done in process
context, we can handle the recycling operation there instead of
deferring the recycling work to another process. Because the
disconnect path drains all work before allowing tear down to
proceed, it is guaranteed that Local Invalidations complete only
while the ri_id pointer is stable.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

MRs are now allocated on demand so we can safely throw them away on
disconnect. This way an idle transport can disconnect and it won't
pin hardware MR resources.

Two additional changes:

- Now that all MRs are destroyed on disconnect, there's no need to
  check during header marshaling if a req has MRs to recycle. Each
  req is sent only once per connection, and now rl_registered is
  guaranteed to be empty when rpcrdma_marshal_req is invoked.

- Because MRs are now destroyed in a WQ_MEM_RECLAIM context, they
  also must be allocated in a WQ_MEM_RECLAIM context. This reduces
  the likelihood that device driver memory allocation will trigger
  memory reclaim during NFS writeback.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Close some holes introduced by commit 6dc6ec9e ("xprtrdma: Cache
free MRs in each rpcrdma_req") that could result in list corruption.

In addition, the result that is tabulated in @count is no longer
used, so @count is removed.

Fixes: 6dc6ec9e ("xprtrdma: Cache free MRs in each rpcrdma_req")
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

A recent clean up attempted to separate Receive handling and RPC
Reply processing, in the name of clean layering.

Unfortunately, we can't do this because the Receive Queue has to be
refilled _after_ the most recent credit update from the responder
is parsed from the transport header, but _before_ we wake up the
next RPC sender. That is right in the middle of
rpcrdma_reply_handler().

Usually this isn't a problem because current responder
implementations don't vary their credit grant. The one exception is
when a connection is established: the grant goes from one to a much
larger number on the first Receive. The requester MUST post enough
Receives right then so that any outstanding requests can be sent
without risking RNR and connection loss.

Fixes: 6ceea368 ("xprtrdma: Refactor Receive accounting")
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Clean up/code de-duplication.

Nit: RPC_CWNDSHIFT is incorrect as the initial value for xprt->cwnd.
This mistake does not appear to have operational consequences, since
the cwnd value is replaced with a valid value upon the first Receive
completion.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

This is because xprt_request_get_cong() is allowing more than one
RPC Call to be transmitted before the first Receive on the new
connection. The first Receive fills the Receive Queue based on the
server's credit grant. Before that Receive, there is only a single
Receive WR posted because the client doesn't know the server's
credit grant.

Solution is to clear rq_cong on all outstanding rpc_rqsts when the
the cwnd is reset. This is because an RPC/RDMA credit is good for
one connection instance only.

Fixes: 75891f50 ("SUNRPC: Support for congestion control ... ")
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

When adding frwr_unmap_async way back when, I re-used the existing
trace_xprtrdma_post_send() trace point to record the return code
of ib_post_send.

Unfortunately there are some cases where re-using that trace point
causes a crash. Instead, construct a trace point specific to posting
Local Invalidate WRs that will always be safe to use in that context,
and will act as a trace log eye-catcher for Local Invalidation.

Fixes: 84756894 ("xprtrdma: Remove fr_state")
Fixes: d8099fed ("xprtrdma: Reduce context switching due ... ")
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Tested-by: NBill Baker <bill.baker@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Eli Dorfman reports that after a series of idle disconnects, an
RPC/RDMA transport becomes unusable (rdma_create_qp returns
-ENOMEM). Problem was tracked down to increasing Send Queue size
after each reconnect.

The rdma_create_qp() API does not promise to leave its @qp_init_attr
parameter unaltered. In fact, some drivers do modify one or more of
its fields. Thus our calls to rdma_create_qp must use a fresh copy
of ib_qp_init_attr each time.

This fix is appropriate for kernels dating back to late 2007, though
it will have to be adapted, as the connect code has changed over the
years.
Reported-by: NEli Dorfman <eli@vastdata.com>
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Ensure that the re-establishment delay does not grow exponentially
on each good reconnect. This probably should have been part of
commit 675dd90a ("xprtrdma: Modernize ops->connect").
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

The optimization done in "xprtrdma: Simplify rpcrdma_mr_pop" was a
bit too optimistic. MRs left over after a reconnect still need to
be recycled, not added back to the free list, since they could be
in flight or actually fully registered.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Micro-optimization: In rpcrdma_post_recvs, since commit e340c2d6
("xprtrdma: Reduce the doorbell rate (Receive)"), the common case is
to return without doing anything. Found with perf.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Micro-optimization: Save the cost of three function calls during
transport header encoding.

These were "noinline" before to generate more meaningful call stacks
during debugging, but this code is now pretty stable.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

For the moment the returned value just happens to be correct because
the current backchannel server implementation does not vary the
number of credits it offers. The spec does permit this value to
change during the lifetime of a connection, however.

The actual maximum is fixed for all RPC/RDMA transports, because
each transport instance has to pre-allocate the resources for
processing BC requests. That's the value that should be returned.

Fixes: 7402a4fe ("SUNRPC: Fix up backchannel slot table ... ")
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Clean up: The function name should match the documenting comment.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

rpcrdma_rep objects are removed from their free list by only a
single thread: the Receive completion handler. Thus that free list
can be converted to an llist, where a single-threaded consumer and
a multi-threaded producer (rpcrdma_buffer_put) can both access the
llist without the need for any serialization.

This eliminates spin lock contention between the Receive completion
handler and rpcrdma_buffer_get, and makes the rep consumer wait-
free.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Clean up: Now that the free list is used sparingly, get rid of the
separate spin lock protecting it.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Instead of a globally-contended MR free list, cache MRs in each
rpcrdma_req as they are released. This means acquiring and releasing
an MR will be lock-free in the common case, even outside the
transport send lock.

The original idea of per-rpcrdma_req MR free lists was suggested by
Shirley Ma <shirley.ma@oracle.com> several years ago. I just now
figured out how to make that idea work with on-demand MR allocation.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Probably would be good to also pass GFP flags to ib_alloc_mr.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Refactor: Retrieve an MR and handle error recovery entirely in
rpc_rdma.c, as this is not a device-specific function.

Note that since commit 89f90fe1 ("SUNRPC: Allow calls to
xprt_transmit() to drain the entire transmit queue"), the
xprt_transmit function handles the cond_resched. The transport no
longer has to do this itself.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Clean up. There is only one remaining rpcrdma_mr_put call site, and
it can be directly replaced with unmap_and_put because mr->mr_dir is
set to DMA_NONE just before the call.

Now all the call sites do a DMA unmap, and we can just rename
mr_unmap_and_put to mr_put, which nicely matches mr_get.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Clean up: rpcrdma_mr_pop call sites check if the list is empty
first. Let's replace the list_empty with less costly logic.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Commit 48be539d ("xprtrdma: Introduce ->alloc_slot call-out for
xprtrdma") added a separate alloc_slot and free_slot to the RPC/RDMA
transport. Later, commit 75891f50 ("SUNRPC: Support for
congestion control when queuing is enabled") modified the generic
alloc/free_slot methods, but neglected the methods in xprtrdma.

Found via code review.

Fixes: 75891f50 ("SUNRPC: Support for congestion control ... ")
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Clean up: There are other "all" list heads. For code clarity
distinguish this one as for use only for MRs by renaming it.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Make the field name the same for all trace points that handle
pointers to struct rpcrdma_rep. That makes it easy to grep for
matching rep points in trace output.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Although I haven't seen any performance results that justify it,
I've received several complaints that NFS/RDMA no longer supports
a maximum rsize and wsize of 1MB. These days it is somewhat smaller.

To simplify the logic that determines whether a chunk list is
necessary, the implementation uses a fixed maximum size of the
transport header. Currently that maximum size is 256 bytes, one
quarter of the default inline threshold size for RPC/RDMA v1.

Since commit a7886849 ("xprtrdma: Reduce max_frwr_depth"), the
size of chunks is also smaller to take advantage of inline page
lists in device internal MR data structures.

The combination of these two design choices has reduced the maximum
NFS rsize and wsize that can be used for most RNIC/HCAs. Increasing
the maximum transport header size and the maximum number of RDMA
segments it can contain increases the negotiated maximum rsize/wsize
on common RNIC/HCAs.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Commit 302d3deb ("xprtrdma: Prevent inline overflow") added this
calculation back in 2016, but got it wrong. I tested only the lower
bound, which is why there is a max_t there. The upper bound should be
rounded up too.

Now, when using DIV_ROUND_UP, that takes care of the lower bound as
well.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Comment was made obsolete by commit 8cec3dba ("xprtrdma:
rpcrdma_regbuf alignment").
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Things have changed since this comment was written. In particular,
the reworking of connection closing, on-demand creation of MRs, and
the removal of fr_state all mean that deferring MR recovery to
frwr_map is no longer needed. The description is obsolete.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Use a wait-free mechanism for managing the svc_rdma_recv_ctxts free
list. Subsequently, sc_recv_lock can be eliminated.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Clean up: the system workqueue will work just as well.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Send and Receive completion is handled on a single CPU selected at
the time each Completion Queue is allocated. Typically this is when
an initiator instantiates an RDMA transport, or when a target
accepts an RDMA connection.

Some ULPs cannot open a connection per CPU to spread completion
workload across available CPUs and MSI vectors. For such ULPs,
provide an API that allows the RDMA core to select a completion
vector based on the device's complement of available comp_vecs.

ULPs that invoke ib_alloc_cq() with only comp_vector 0 are converted
to use the new API so that their completion workloads interfere less
with each other.
Suggested-by: NHåkon Bugge <haakon.bugge@oracle.com>
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Reviewed-by: NLeon Romanovsky <leonro@mellanox.com>
Cc: <linux-cifs@vger.kernel.org>
Cc: <v9fs-developer@lists.sourceforge.net>
Link: https://lore.kernel.org/r/20190729171923.13428.52555.stgit@manet.1015granger.netSigned-off-by: NDoug Ledford <dledford@redhat.com>

In the sysctl code the proc_dointvec_minmax() function is often used to
validate the user supplied value between an allowed range.  This
function uses the extra1 and extra2 members from struct ctl_table as
minimum and maximum allowed value.

On sysctl handler declaration, in every source file there are some
readonly variables containing just an integer which address is assigned
to the extra1 and extra2 members, so the sysctl range is enforced.

The special values 0, 1 and INT_MAX are very often used as range
boundary, leading duplication of variables like zero=0, one=1,
int_max=INT_MAX in different source files:

    $ git grep -E '\.extra[12].*&(zero|one|int_max)' |wc -l
    248

Add a const int array containing the most commonly used values, some
macros to refer more easily to the correct array member, and use them
instead of creating a local one for every object file.

This is the bloat-o-meter output comparing the old and new binary
compiled with the default Fedora config:

    # scripts/bloat-o-meter -d vmlinux.o.old vmlinux.o
    add/remove: 2/2 grow/shrink: 0/2 up/down: 24/-188 (-164)
    Data                                         old     new   delta
    sysctl_vals                                    -      12     +12
    __kstrtab_sysctl_vals                          -      12     +12
    max                                           14      10      -4
    int_max                                       16       -     -16
    one                                           68       -     -68
    zero                                         128      28    -100
    Total: Before=20583249, After=20583085, chg -0.00%

[mcroce@redhat.com: tipc: remove two unused variables]
  Link: http://lkml.kernel.org/r/20190530091952.4108-1-mcroce@redhat.com
[akpm@linux-foundation.org: fix net/ipv6/sysctl_net_ipv6.c]
[arnd@arndb.de: proc/sysctl: make firmware loader table conditional]
  Link: http://lkml.kernel.org/r/20190617130014.1713870-1-arnd@arndb.de
[akpm@linux-foundation.org: fix fs/eventpoll.c]
Link: http://lkml.kernel.org/r/20190430180111.10688-1-mcroce@redhat.comSigned-off-by: NMatteo Croce <mcroce@redhat.com>
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NKees Cook <keescook@chromium.org>
Reviewed-by: NAaron Tomlin <atomlin@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add a per-transport maximum limit in the socket case, and add
helpers to allow the NFSv4 code to discover that limit.
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>

Adapt and apply changes that were made to the TCP socket connect
code. See the following commits for details on the purpose of
these changes:

Commit 7196dbb0 ("SUNRPC: Allow changing of the TCP timeout parameters on the fly")
Commit 3851f1cd ("SUNRPC: Limit the reconnect backoff timer to the max RPC message timeout")
Commit 02910177 ("SUNRPC: Fix reconnection timeouts")

Some common transport code is moved to xprt.c to satisfy the code
duplication police.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Clean up.

There is only one remaining function, rpcrdma_buffer_put(), that
uses this field. Its caller can supply a pointer to the correct
rpcrdma_buffer, enabling the removal of an 8-byte pointer field
from a frequently-allocated shared data structure.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Clean up.

Move the "not present" case into the individual chunk encoders. This
improves code organization and readability.

The reason for the original organization was to optimize for the
case where there there are no chunks. The optimization turned out to
be inconsequential, so let's err on the side of code readability.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

rb_lock is contended between rpcrdma_buffer_create,
rpcrdma_buffer_put, and rpcrdma_post_recvs.

Commit e340c2d6 ("xprtrdma: Reduce the doorbell rate (Receive)")
causes rpcrdma_post_recvs to take the rb_lock repeatedly when it
determines more Receives are needed. Streamline this code path so
it takes the lock just once in most cases to build the Receive
chain that is about to be posted.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Clean up.

Commit 7c8d9e7c ("xprtrdma: Move Receive posting to Receive
handler") reduced the number of rpcrdma_rep_create call sites to
one. After that commit, the backchannel code no longer invokes it.

Therefore the free list logic added by commit d698c4a0
("xprtrdma: Fix backchannel allocation of extra rpcrdma_reps") is
no longer necessary, and in fact adds some extra overhead that we
can do without.

Simply post any newly created reps. They will get added back to
the rb_recv_bufs list when they subsequently complete.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>