Commit Graph

122 Commits

Author SHA1 Message Date
Chuck Lever
d96962e6d0 svcrdma: Use the new parsed chunk list when pulling Read chunks
As a pre-requisite for handling multiple Read chunks in each Read
list, convert svc_rdma_recv_read_chunk() to use the new parsed Read
chunk list.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-11-30 13:00:23 -05:00
Chuck Lever
7954c8503b svcrdma: Remove chunk list pointers
Clean up: These pointers are no longer used.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-11-30 13:00:23 -05:00
Chuck Lever
9d0b09d5ef svcrdma: Support multiple write chunks when pulling up
When counting the number of SGEs needed to construct a Send request,
do not count result payloads. And, when copying the Reply message
into the pull-up buffer, result payloads are not to be copied to the
Send buffer.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-11-30 13:00:22 -05:00
Chuck Lever
7a1cbfa180 svcrdma: Use parsed chunk lists to construct RDMA Writes
Refactor: Instead of re-parsing the ingress RPC Call transport
header when constructing RDMA Writes, use the new parsed chunk lists
for the Write list and Reply chunk, which are version-agnostic and
already XDR-decoded.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-11-30 13:00:22 -05:00
Chuck Lever
58b2e0fefa svcrdma: Use parsed chunk lists to detect reverse direction replies
Refactor: Don't duplicate header decoding smarts here. Instead, use
the new parsed chunk lists.

Note that the XID sanity test is also removed. The XID is already
looked up by the cb handler, and is rejected if it's not recognized.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-11-30 13:00:22 -05:00
Chuck Lever
eb3de6a49d svcrdma: Use parsed chunk lists to derive the inv_rkey
Refactor: Don't duplicate header decoding smarts here. Instead, use
the new parsed chunk lists.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-11-30 13:00:22 -05:00
Chuck Lever
78147ca8b4 svcrdma: Add a "parsed chunk list" data structure
This simple data structure binds the location of each data payload
inside of an RPC message to the chunk that will be used to push it
to or pull it from the client.

There are several benefits to this small additional overhead:

 * It enables support for more than one chunk in incoming Read and
   Write lists.

 * It translates the version-specific on-the-wire format into a
   generic in-memory structure, enabling support for multiple
   versions of the RPC/RDMA transport protocol.

 * It enables the server to re-organize a chunk list if it needs to
   adjust where Read chunk data lands in server memory without
   altering the contents of the XDR-encoded Receive buffer.

Construction of these lists is done while sanity checking each
incoming RPC/RDMA header. Subsequent patches will make use of the
generated data structures.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-11-30 13:00:22 -05:00
Chuck Lever
365e9992b9 svcrdma: Remove transport reference counting
Jason tells me that a ULP cannot rely on getting an ESTABLISHED
and DISCONNECTED event pair for each connection, so transport
reference counting in the CM event handler will never be reliable.

Now that we have ib_drain_qp(), svcrdma should no longer need to
hold transport references while Sends and Receives are posted. So
remove the get/put call sites in the CM event handlers.

This eliminates a significant source of locked memory bus traffic.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-07-28 10:18:14 -04:00
Chuck Lever
64d2642251 svcrdma: Fix another Receive buffer leak
During a connection tear down, the Receive queue is flushed before
the device resources are freed. Typically, all the Receives flush
with IB_WR_FLUSH_ERR.

However, any pending successful Receives flush with IB_WR_SUCCESS,
and the server automatically posts a fresh Receive to replace the
completing one. This happens even after the connection has closed
and the RQ is drained. Receives that are posted after the RQ is
drained appear never to complete, causing a Receive resource leak.
The leaked Receive buffer is left DMA-mapped.

To prevent these late-posted recv_ctxt's from leaking, block new
Receive posting after XPT_CLOSE is set.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-07-28 10:18:13 -04:00
Chuck Lever
007140ee9b svcrdma: Record Receive completion ID in svc_rdma_decode_rqst
When recording a trace event in the Receive path, tie decoding
results and errors to an incoming Receive completion.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-07-13 17:28:24 -04:00
Chuck Lever
9b3bcf8c5c svcrdma: Introduce Receive completion IDs
Set up a completion ID in each svc_rdma_recv_ctxt. The ID is used
to match an incoming Receive completion to a transport and to a
previous ib_post_recv().

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-07-13 17:28:24 -04:00
Chuck Lever
f60a08697d svcrdma: Add common XDR decoders for RDMA and Read segments
Clean up: De-duplicate some code.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-07-13 17:28:24 -04:00
Chuck Lever
07e9a6325a SUNRPC: Add helpers for decoding list discriminators symbolically
Use these helpers in a few spots to demonstrate their use.

The remaining open-coded discriminator checks in rpcrdma will be
addressed in subsequent patches.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-07-13 17:28:24 -04:00
Chuck Lever
ba6cc97738 svcrdma: Consolidate send_error helper functions
Final refactor: Replace internals of svc_rdma_send_error() with a
simple call to svc_rdma_send_error_msg().

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-07-13 17:28:24 -04:00
Chuck Lever
d1f6e2369c svcrdma: Add @rctxt parameter to svc_rdma_send_error() functions
Another step towards making svc_rdma_send_error_msg() and
svc_rdma_send_error() similar enough to eliminate one of them.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-07-13 17:28:24 -04:00
Chuck Lever
27ce629444 svcrdma: Rename tracepoints that record header decoding errors
Clean up: Use a consistent naming convention so that these trace
points can be enabled quickly via a glob.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-05-18 10:21:21 -04:00
Chuck Lever
ea740bd5f5 svcrdma: Fix backchannel return code
Way back when I was writing the RPC/RDMA server-side backchannel
code, I misread the TCP backchannel reply handler logic. When
svc_tcp_recvfrom() successfully receives a backchannel reply, it
does not return -EAGAIN. It sets XPT_DATA and returns zero.

Update svc_rdma_recvfrom() to return zero. Here, XPT_DATA doesn't
need to be set again: it is set whenever a new message is received,
behind a spin lock in a single threaded context.

Also, if handling the cb reply is not successful, the message is
simply dropped. There's no special message framing to deal with as
there is in the TCP case.

Now that the handle_bc_reply() return value is ignored, I've removed
the dprintk call sites in the error exit of handle_bc_reply() in
favor of trace points in other areas that already report the error
cases.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-05-18 10:21:21 -04:00
Chuck Lever
23cf1ee1f1 svcrdma: Fix leak of svc_rdma_recv_ctxt objects
Utilize the xpo_release_rqst transport method to ensure that each
rqstp's svc_rdma_recv_ctxt object is released even when the server
cannot return a Reply for that rqstp.

Without this fix, each RPC whose Reply cannot be sent leaks one
svc_rdma_recv_ctxt. This is a 2.5KB structure, a 4KB DMA-mapped
Receive buffer, and any pages that might be part of the Reply
message.

The leak is infrequent unless the network fabric is unreliable or
Kerberos is in use, as GSS sequence window overruns, which result
in connection loss, are more common on fast transports.

Fixes: 3a88092ee3 ("svcrdma: Preserve Receive buffer until svc_rdma_sendto")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-04-17 12:40:38 -04:00
Chuck Lever
aee4b74a3f svcrdma: Fix double sync of transport header buffer
Performance optimization: Avoid syncing the transport buffer twice
when Reply buffer pull-up is necessary.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-03-16 12:04:33 -04:00
Chuck Lever
6fd5034db4 svcrdma: Refactor chunk list encoders
Same idea as the receive-side changes I did a while back: use
xdr_stream helpers rather than open-coding the XDR chunk list
encoders. This builds the Reply transport header from beginning to
end without backtracking.

As additional clean-ups, fill in documenting comments for the XDR
encoders and sprinkle some trace points in the new encoding
functions.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-03-16 12:04:33 -04:00
Chuck Lever
2fe8c44633 svcrdma: De-duplicate code that locates Write and Reply chunks
Cache the locations of the Requester-provided Write list and Reply
chunk so that the Send path doesn't need to parse the Call header
again.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-03-16 12:04:32 -04:00
Chuck Lever
e604aad2ca svcrdma: Use struct xdr_stream to decode ingress transport headers
The logic that checks incoming network headers has to be scrupulous.

De-duplicate: replace open-coded buffer overflow checks with the use
of xdr_stream helpers that are used most everywhere else XDR
decoding is done.

One minor change to the sanity checks: instead of checking the
length of individual segments, cap the length of the whole chunk
to be sure it can fit in the set of pages available in rq_pages.
This should be a better test of whether the server can handle the
chunks in each request.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-03-16 12:04:32 -04:00
Chuck Lever
412055398b nfsd: Fix NFSv4 READ on RDMA when using readv
svcrdma expects that the payload falls precisely into the xdr_buf
page vector. This does not seem to be the case for
nfsd4_encode_readv().

This code is called only when fops->splice_read is missing or when
RQ_SPLICE_OK is clear, so it's not a noticeable problem in many
common cases.

Add new transport method: ->xpo_read_payload so that when a READ
payload does not fit exactly in rq_res's page vector, the XDR
encoder can inform the RPC transport exactly where that payload is,
without the payload's XDR pad.

That way, when a Write chunk is present, the transport knows what
byte range in the Reply message is supposed to be matched with the
chunk.

Note that the Linux NFS server implementation of NFS/RDMA can
currently handle only one Write chunk per RPC-over-RDMA message.
This simplifies the implementation of this fix.

Fixes: b042098063 ("nfsd4: allow exotic read compounds")
Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=198053
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-03-16 12:04:31 -04:00
Chuck Lever
4866073e6d svcrdma: Use llist for managing cache of recv_ctxts
Use a wait-free mechanism for managing the svc_rdma_recv_ctxts free
list. Subsequently, sc_recv_lock can be eliminated.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2019-08-19 10:59:28 -04:00
Chuck Lever
8820bcaa5b svcrdma: Remove syslog warnings in work completion handlers
These can result in a lot of log noise, and are able to be triggered
by client misbehavior. Since there are trace points in these
handlers now, there's no need to spam the log.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2019-02-06 15:37:15 -05:00
J. Bruce Fields
95503d295a svcrpc: fix unlikely races preventing queueing of sockets
In the rpc server, When something happens that might be reason to wake
up a thread to do something, what we do is

	- modify xpt_flags, sk_sock->flags, xpt_reserved, or
	  xpt_nr_rqsts to indicate the new situation
	- call svc_xprt_enqueue() to decide whether to wake up a thread.

svc_xprt_enqueue may require multiple conditions to be true before
queueing up a thread to handle the xprt.  In the SMP case, one of the
other CPU's may have set another required condition, and in that case,
although both CPUs run svc_xprt_enqueue(), it's possible that neither
call sees the writes done by the other CPU in time, and neither one
recognizes that all the required conditions have been set.  A socket
could therefore be ignored indefinitely.

Add memory barries to ensure that any svc_xprt_enqueue() call will
always see the conditions changed by other CPUs before deciding to
ignore a socket.

I've never seen this race reported.  In the unlikely event it happens,
another event will usually come along and the problem will fix itself.
So I don't think this is worth backporting to stable.

Chuck tried this patch and said "I don't see any performance
regressions, but my server has only a single last-level CPU cache."

Tested-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2019-02-06 15:37:14 -05:00
Chuck Lever
97bce63408 svcrdma: Optimize the logic that selects the R_key to invalidate
o Select the R_key to invalidate while the CPU cache still contains
  the received RPC Call transport header, rather than waiting until
  we're about to send the RPC Reply.

o Choose Send With Invalidate if there is exactly one distinct R_key
  in the received transport header. If there's more than one, the
  client will have to perform local invalidation after it has
  already waited for remote invalidation.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2018-11-28 18:36:03 -05:00
Linus Torvalds
9157141c95 A mistake on my part caused me to tag my branch 6 commits too early,
missing Chuck's fixes for the problem with callbacks over GSS from
 multi-homed servers, and a smaller fix from Laura Abbott.
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Merge tag 'nfsd-4.19-1' of git://linux-nfs.org/~bfields/linux

Pull nfsd updates from Bruce Fields:
 "Chuck Lever fixed a problem with NFSv4.0 callbacks over GSS from
  multi-homed servers.

  The only new feature is a minor bit of protocol (change_attr_type)
  which the client doesn't even use yet.

  Other than that, various bugfixes and cleanup"

* tag 'nfsd-4.19-1' of git://linux-nfs.org/~bfields/linux: (27 commits)
  sunrpc: Add comment defining gssd upcall API keywords
  nfsd: Remove callback_cred
  nfsd: Use correct credential for NFSv4.0 callback with GSS
  sunrpc: Extract target name into svc_cred
  sunrpc: Enable the kernel to specify the hostname part of service principals
  sunrpc: Don't use stack buffer with scatterlist
  rpc: remove unneeded variable 'ret' in rdma_listen_handler
  nfsd: use true and false for boolean values
  nfsd: constify write_op[]
  fs/nfsd: Delete invalid assignment statements in nfsd4_decode_exchange_id
  NFSD: Handle full-length symlinks
  NFSD: Refactor the generic write vector fill helper
  svcrdma: Clean up Read chunk path
  svcrdma: Avoid releasing a page in svc_xprt_release()
  nfsd: Mark expected switch fall-through
  sunrpc: remove redundant variables 'checksumlen','blocksize' and 'data'
  nfsd: fix leaked file lock with nfs exported overlayfs
  nfsd: don't advertise a SCSI layout for an unsupported request_queue
  nfsd: fix corrupted reply to badly ordered compound
  nfsd: clarify check_op_ordering
  ...
2018-08-23 16:00:10 -07:00
Chuck Lever
a53d5cb064 svcrdma: Avoid releasing a page in svc_xprt_release()
svc_xprt_release() invokes svc_free_res_pages(), which releases
pages between rq_respages and rq_next_page.

Historically, the RPC/RDMA transport has set these two pointers to
be different by one, which means:

- one page gets released when svc_recv returns 0. This normally
happens whenever one or more RDMA Reads need to be dispatched to
complete construction of an RPC Call.

- one page gets released after every call to svc_send.

In both cases, this released page is immediately refilled by
svc_alloc_arg. There does not seem to be a reason for releasing this
page.

To avoid this unnecessary memory allocator traffic, set rq_next_page
more carefully.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2018-08-09 16:11:21 -04:00
Bart Van Assche
ed288d74a9 net/xprtrdma: Simplify ib_post_(send|recv|srq_recv)() calls
Instead of declaring and passing a dummy 'bad_wr' pointer, pass NULL
as third argument to ib_post_(send|recv|srq_recv)().

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Acked-by: Anna Schumaker <Anna.Schumaker@netapp.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
2018-07-24 16:06:37 -06:00
Chuck Lever
af7fd74ec2 svcrdma: Fix incorrect return value/type in svc_rdma_post_recvs
This crept in during the development process and wasn't caught
before I posted the "final" version.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 0b2613c5883f ('svcrdma: Allocate recv_ctxt's on CPU ... ')
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2018-06-08 16:28:55 -04:00
Chuck Lever
99722fe4d5 svcrdma: Persistently allocate and DMA-map Send buffers
While sending each RPC Reply, svc_rdma_sendto allocates and DMA-
maps a separate buffer where the RPC/RDMA transport header is
constructed. The buffer is unmapped and released in the Send
completion handler. This is significant per-RPC overhead,
especially for small RPCs.

Instead, allocate and DMA-map a buffer, and cache it in each
svc_rdma_send_ctxt. This buffer and its mapping can be re-used
for each RPC, saving the cost of memory allocation and DMA
mapping.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2018-05-11 15:48:57 -04:00
Chuck Lever
986b78894b svcrdma: Remove post_send_wr
Clean up: Now that the send_wr is part of the svc_rdma_send_ctxt,
svc_rdma_post_send_wr is nearly empty.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2018-05-11 15:48:57 -04:00
Chuck Lever
4201c74647 svcrdma: Introduce svc_rdma_send_ctxt
svc_rdma_op_ctxt's are pre-allocated and maintained on a per-xprt
free list. This eliminates the overhead of calling kmalloc / kfree,
both of which grab a globally shared lock that disables interrupts.
Introduce a replacement to svc_rdma_op_ctxt's that is built
especially for the svcrdma Send path.

Subsequent patches will take advantage of this new structure by
allocating real resources which are then cached in these objects.
The allocations are freed when the transport is torn down.

I've renamed the structure so that static type checking can be used
to ensure that uses of op_ctxt and send_ctxt are not confused. As an
additional clean up, structure fields are renamed to conform with
kernel coding conventions.

Additional clean ups:
- Handle svc_rdma_send_ctxt_get allocation failure at each call
  site, rather than pre-allocating and hoping we guessed correctly
- All send_ctxt_put call-sites request page freeing, so remove
  the @free_pages argument
- All send_ctxt_put call-sites unmap SGEs, so fold that into
  svc_rdma_send_ctxt_put

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2018-05-11 15:48:57 -04:00
Chuck Lever
232627905f svcrdma: Clean up Send SGE accounting
Clean up: Since there's already a svc_rdma_op_ctxt being passed
around with the running count of mapped SGEs, drop unneeded
parameters to svc_rdma_post_send_wr().

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2018-05-11 15:48:57 -04:00
Chuck Lever
eb5d7a622e svcrdma: Allocate recv_ctxt's on CPU handling Receives
There is a significant latency penalty when processing an ingress
Receive if the Receive buffer resides in memory that is not on the
same NUMA node as the the CPU handling completions for a CQ.

The system administrator and the device driver determine which CPU
handles completions. This CPU does not change during life of the CQ.
Further the Upper Layer does not have any visibility of which CPU it
is.

Allocating Receive buffers in the Receive completion handler
guarantees that Receive buffers are allocated on the preferred NUMA
node for that CQ.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2018-05-11 15:48:57 -04:00
Chuck Lever
3316f06311 svcrdma: Persistently allocate and DMA-map Receive buffers
The current Receive path uses an array of pages which are allocated
and DMA mapped when each Receive WR is posted, and then handed off
to the upper layer in rqstp::rq_arg. The page flip releases unused
pages in the rq_pages pagelist. This mechanism introduces a
significant amount of overhead.

So instead, kmalloc the Receive buffer, and leave it DMA-mapped
while the transport remains connected. This confers a number of
benefits:

* Each Receive WR requires only one receive SGE, no matter how large
  the inline threshold is. This helps the server-side NFS/RDMA
  transport operate on less capable RDMA devices.

* The Receive buffer is left allocated and mapped all the time. This
  relieves svc_rdma_post_recv from the overhead of allocating and
  DMA-mapping a fresh buffer.

* svc_rdma_wc_receive no longer has to DMA unmap the Receive buffer.
  It has to DMA sync only the number of bytes that were received.

* svc_rdma_build_arg_xdr no longer has to free a page in rq_pages
  for each page in the Receive buffer, making it a constant-time
  function.

* The Receive buffer is now plugged directly into the rq_arg's
  head[0].iov_vec, and can be larger than a page without spilling
  over into rq_arg's page list. This enables simplification of
  the RDMA Read path in subsequent patches.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2018-05-11 15:48:57 -04:00
Chuck Lever
3a88092ee3 svcrdma: Preserve Receive buffer until svc_rdma_sendto
Rather than releasing the incoming svc_rdma_recv_ctxt at the end of
svc_rdma_recvfrom, hold onto it until svc_rdma_sendto.

This permits the contents of the Receive buffer to be preserved
through svc_process and then referenced directly in sendto as it
constructs Write and Reply chunks to return to the client.

The real changes will come in subsequent patches.

Note: I cannot use ->xpo_release_rqst for this purpose because that
is called _before_ ->xpo_sendto. svc_rdma_sendto uses information in
the received Call transport header to construct the Reply transport
header, which is preserved in the RPC's Receive buffer.

The historical comment in svc_send() isn't helpful: it is already
obvious that ->xpo_release_rqst is being called before ->xpo_sendto,
but there is no explanation for this ordering going back to the
beginning of the git era.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2018-05-11 15:48:57 -04:00
Chuck Lever
1e5f416074 svcrdma: Simplify svc_rdma_recv_ctxt_put
Currently svc_rdma_recv_ctxt_put's callers have to know whether they
want to free the ctxt's pages or not. This means the human
developers have to know when and why to set that free_pages
argument.

Instead, the ctxt should carry that information with it so that
svc_rdma_recv_ctxt_put does the right thing no matter who is
calling.

We want to keep track of the number of pages in the Receive buffer
separately from the number of pages pulled over by RDMA Read. This
is so that the correct number of pages can be freed properly and
that number is well-documented.

So now, rc_hdr_count is the number of pages consumed by head[0]
(ie., the page index where the Read chunk should start); and
rc_page_count is always the number of pages that need to be released
when the ctxt is put.

The @free_pages argument is no longer needed.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2018-05-11 15:48:57 -04:00
Chuck Lever
ecf85b2384 svcrdma: Introduce svc_rdma_recv_ctxt
svc_rdma_op_ctxt's are pre-allocated and maintained on a per-xprt
free list. This eliminates the overhead of calling kmalloc / kfree,
both of which grab a globally shared lock that disables interrupts.
To reduce contention further, separate the use of these objects in
the Receive and Send paths in svcrdma.

Subsequent patches will take advantage of this separation by
allocating real resources which are then cached in these objects.
The allocations are freed when the transport is torn down.

I've renamed the structure so that static type checking can be used
to ensure that uses of op_ctxt and recv_ctxt are not confused. As an
additional clean up, structure fields are renamed to conform with
kernel coding conventions.

As a final clean up, helpers related to recv_ctxt are moved closer
to the functions that use them.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2018-05-11 15:48:57 -04:00
Chuck Lever
bd2abef333 svcrdma: Trace key RDMA API events
This includes:
  * Posting on the Send and Receive queues
  * Send, Receive, Read, and Write completion
  * Connect upcalls
  * QP errors

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2018-05-11 15:48:57 -04:00
Chuck Lever
98895edbe3 svcrdma: Trace key RPC/RDMA protocol events
This includes:
  * Transport accept and tear-down
  * Decisions about using Write and Reply chunks
  * Each RDMA segment that is handled
  * Whenever an RDMA_ERR is sent

As a clean-up, I've standardized the order of the includes, and
removed some now redundant dprintk call sites.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2018-05-11 15:48:57 -04:00
Chuck Lever
bcf3ffd405 svcrdma: Add proper SPDX tags for NetApp-contributed source
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2018-05-11 15:48:57 -04:00
Chuck Lever
6f29d07ca4 svcrdma: Clean up rdma_build_arg_xdr
Clean up: The value of the byte_count parameter is already passed
to rdma_build_arg_xdr as part of the svc_rdma_op_ctxt structure.

Further, without the parameter called "byte_count" there is no need
to have the abbreviated "bc" automatic variable. "bc" can now be
called something more intuitive.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2018-03-20 17:32:13 -04:00
Chuck Lever
482725027f svcrdma: Post Receives in the Receive completion handler
This change improves Receive efficiency by posting Receives only
on the same CPU that handles Receive completion. Improved latency
and throughput has been noted with this change.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2018-01-18 11:52:51 -05:00
Chuck Lever
71641d99ce svcrdma: Properly compute .len and .buflen for received RPC Calls
When an RPC-over-RDMA request is received, the Receive buffer
contains a Transport Header possibly followed by an RPC message.

Even though rq_arg.head[0] (as passed to NFSD) does not contain the
Transport Header header, currently rq_arg.len includes the size of
the Transport Header.

That violates the intent of the xdr_buf API contract. .buflen should
include everything, but .len should be exactly the length of the RPC
message in the buffer.

The rq_arg fields are summed together at the end of
svc_rdma_recvfrom to obtain the correct return value. rq_arg.len
really ought to contain the correct number of bytes already, but it
currently doesn't due to the above misbehavior.

Let's instead ensure that .buflen includes the length of the
transport header, and that .len is always equal to head.iov_len +
.page_len + tail.iov_len .

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2017-07-12 15:54:57 -04:00
Chuck Lever
cafc739892 svcrdma: Use generic RDMA R/W API in RPC Call path
The current svcrdma recvfrom code path has a lot of detail about
registration mode and the type of port (iWARP, IB, etc).

Instead, use the RDMA core's generic R/W API. This shares code with
other RDMA-enabled ULPs that manages the gory details of buffer
registration and the posting of RDMA Read Work Requests.

Since the Read list marshaling code is being replaced, I took the
opportunity to replace C structure-based XDR encoding code with more
portable code that uses pointer arithmetic.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2017-07-12 15:54:56 -04:00
Chuck Lever
2d6491a56c svcrdma: Don't account for Receive queue "starvation"
>From what I can tell, calling ->recvfrom when there is no work to do
is a normal part of operation. This is the only way svc_recv can
tell when there is no more data ready to receive on the transport.

Neither the TCP nor the UDP transport implementations have a
"starve" metric.

The cost of receive starvation accounting is bumping an atomic, which
results in extra (IMO unnecessary) bus traffic between CPU sockets,
while holding a spin lock.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2017-06-28 14:21:44 -04:00
Chuck Lever
ca5c76aba7 svcrdma: Improve Reply chunk sanity checking
Identify malformed transport headers and unsupported chunk
combinations as early as possible.

- Ensure that segment lengths are not crazy.

- Ensure that the Reply chunk's segment count is not crazy.

With a 1KB inline threshold, the largest number of Write segments
that can be conveyed is about 60 (for a RDMA_NOMSG Reply message).

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2017-06-28 14:21:44 -04:00
Chuck Lever
3c22f32607 svcrdma: Improve Write chunk sanity checking
Identify malformed transport headers and unsupported chunk
combinations as early as possible.

- Reject RPC-over-RDMA messages that contain more than one Write
chunk, since this implementation does not support more than one per
message.

- Ensure that segment lengths are not crazy.

- Ensure that the chunk's segment count is not crazy.

With a 1KB inline threshold, the largest number of Write segments
that can be conveyed is about 60 (for a RDMA_NOMSG Reply message).

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2017-06-28 14:21:44 -04:00