summaryrefslogtreecommitdiff
path: root/net/sunrpc/xprtrdma/verbs.c
AgeCommit message (Collapse)Author
2018-06-04Merge tag 'nfs-rdma-for-4.18-1' of ↵Trond Myklebust
git://git.linux-nfs.org/projects/anna/linux-nfs NFS-over-RDMA client updates for Linux 4.18 Stable patches: - xprtrdma: Return -ENOBUFS when no pages are available New features: - Add ->alloc_slot() and ->free_slot() functions Bugfixes and cleanups: - Add missing SPDX tags to some files - Try to fail mount quickly if client has no RDMA devices - Create transport IDs in the correct network namespace - Fix max_send_wr computation - Clean up receive tracepoints - Refactor receive handling - Remove unused functions
2018-06-01xprtrdma: Wait on empty sendctx queueChuck Lever
Currently, when the sendctx queue is exhausted during marshaling, the RPC/RDMA transport places the RPC task on the delayq, which forces a wait for HZ >> 2 before the marshal and send is retried. With this change, the transport now places such an RPC task on the pending queue, and wakes it just as soon as more sendctxs become available. This typically takes less than a millisecond, and the write_space waking mechanism is less deadlock-prone. Moreover, the waiting RPC task is holding the transport's write lock, which blocks the transport from sending RPCs. Therefore faster recovery from sendctx queue exhaustion is desirable. Cf. commit 5804891455d5 ("xprtrdma: ->send_request returns -EAGAIN when there are no free MRs"). Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-05-11xprtrdma: Prepare RPC/RDMA includes for server-side trace pointsChuck Lever
Clean up: Move #include <trace/events/rpcrdma.h> into source files, similar to how it is done with trace/events/sunrpc.h. Server-side trace points will be part of the rpcrdma subsystem, just like the client-side trace points. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2018-05-07xprtrdma: Make rpcrdma_sendctx_put_locked() a static functionChuck Lever
Clean up: The only call site is in the same file as the function's definition. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-05-07xprtrdma: Remove rpcrdma_buffer_get_rep_locked()Chuck Lever
Clean up: There is only one remaining call site for this helper. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-05-07xprtrdma: Remove rpcrdma_buffer_get_req_locked()Chuck Lever
Clean up. There is only one call-site for this helper, and it can be simplified by using list_first_entry_or_null(). Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-05-07xprtrdma: Remove rpcrdma_ep_{post_recv, post_extra_recv}Chuck Lever
Clean up: These functions are no longer used. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-05-07xprtrdma: Move Receive posting to Receive handlerChuck Lever
Receive completion and Reply handling are done by a BOUND workqueue, meaning they run on only one CPU. Posting receives is currently done in the send_request path, which on large systems is typically done on a different CPU than the one handling Receive completions. This results in movement of Receive-related cachelines between the sending and receiving CPUs. More importantly, it means that currently Receives are posted while the transport's write lock is held, which is unnecessary and costly. Finally, allocation of Receive buffers is performed on-demand in the Receive completion handler. This helps guarantee that they are allocated on the same NUMA node as the CPU that handles Receive completions. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-05-07xprtrdma: Clean up Receive trace pointsChuck Lever
For clarity, report the posting and completion of Receive CQEs. Also, the wc->byte_len field contains garbage if wc->status is non-zero, and the vendor error field contains garbage if wc->status is zero. For readability, don't save those fields in those cases. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-05-07xprtrdma: Fix max_send_wr computationChuck Lever
For FRWR, the computation of max_send_wr is split between frwr_op_open and rpcrdma_ep_create, which makes it difficult to tell that the max_send_wr result is currently incorrect if frwr_op_open has to reduce the credit limit to accommodate a small max_qp_wr. This is a problem now that extra WRs are needed for backchannel operations and a drain CQE. So, refactor the computation so that it is all done in ->ro_open, and fix the FRWR version of this computation so that it accommodates HCAs with small max_qp_wr correctly. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-05-07xprtrdma: Create transport's CM ID in the correct network namespaceChuck Lever
Set up RPC/RDMA transport in mount.nfs's network namespace. This passes the correct namespace information to the RDMA core, similar to how RPC sockets are created (see xs_create_sock). Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-05-07xprtrdma: Try to fail quickly if proto=rdmaChuck Lever
rdma_resolve_addr(3) says: > This call is used to map a given destination IP address to a > usable RDMA address. The IP to RDMA address mapping is done > using the local routing tables, or via ARP. If this can't be done, there's no local device that can be used to establish an RDMA-capable network path to the remote. In this case, the RDMA CM very quickly posts an RDMA_CM_EVENT_ADDR_ERROR upcall. Currently rpcrdma_conn_upcall() converts RDMA_CM_EVENT_ADDR_ERROR to EHOSTUNREACH. mount.nfs seems to want to retry EHOSTUNREACH forever, thinking that this is a temporary situation. This makes mount.nfs appear to hang if I try to mount with proto=rdma through, say, a conventional Ethernet device. If the admin has specified proto=rdma along with a server IP address that requires a network path that does not support RDMA, instead let's fail with a permanent error. -EPROTONOSUPPORT is returned when NFSv4 or one of its minor versions is not supported. -EPROTO is not (currently) retried by mount.nfs. There are potentially other similar cases where -EPROTO is an appropriate return code. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Tested-by: Olga Kornievskaia <kolga@netapp.com> Tested-by: Anna Schumaker <Anna.Schumaker@netapp.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-05-07xprtrdma: Add proper SPDX tags for NetApp-contributed sourceChuck Lever
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-05-01xprtrdma: Fix list corruption / DMAR errors during MR recoveryChuck Lever
The ro_release_mr methods check whether mr->mr_list is empty. Therefore, be sure to always use list_del_init when removing an MR linked into a list using that field. Otherwise, when recovering from transport failures or device removal, list corruption can result, or MRs can get mapped or unmapped an odd number of times, resulting in IOMMU-related failures. In general this fix is appropriate back to v4.8. However, code changes since then make it impossible to apply this patch directly to stable kernels. The fix would have to be applied by hand or reworked for kernels earlier than v4.16. Backport guidance -- there are several cases: - When creating an MR, initialize mr_list so that using list_empty on an as-yet-unused MR is safe. - When an MR is being handled by the remote invalidation path, ensure that mr_list is reinitialized when it is removed from rl_registered. - When an MR is being handled by rpcrdma_destroy_mrs, it is removed from mr_all, but it may still be on an rl_registered list. In that case, the MR needs to be removed from that list before being released. - Other cases are covered by using list_del_init in rpcrdma_mr_pop. Fixes: 9d6b04097882 ('xprtrdma: Place registered MWs on a ... ') Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-04-10xprtrdma: Fix corner cases when handling device removalChuck Lever
Michal Kalderon has found some corner cases around device unload with active NFS mounts that I didn't have the imagination to test when xprtrdma device removal was added last year. - The ULP device removal handler is responsible for deallocating the PD. That wasn't clear to me initially, and my own testing suggested it was not necessary, but that is incorrect. - The transport destruction path can no longer assume that there is a valid ID. - When destroying a transport, ensure that ib_free_cq() is not invoked on a CQ that was already released. Reported-by: Michal Kalderon <Michal.Kalderon@cavium.com> Fixes: bebd031866ca ("xprtrdma: Support unplugging an HCA from ...") Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Cc: stable@vger.kernel.org # v4.12+ Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-04-10xprtrdma: Move creation of rl_rdmabuf to rpcrdma_create_reqChuck Lever
Refactor: Both rpcrdma_create_req call sites have to allocate the buffer where the transport header is built, so just move that allocation into rpcrdma_create_req. This buffer is a fixed size. There's no needed information available in call_allocate that is not also available when the transport is created. The original purpose for allocating these buffers on demand was to reduce the possibility that an allocation failure during transport creation will hork the mount operation during low memory scenarios. Some relief for this rare possibility is coming up in the next few patches. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-04-10xprtrdma: Chain Send to FastReg WRsChuck Lever
With FRWR, the client transport can perform memory registration and post a Send with just a single ib_post_send. This reduces contention between the send_request path and the Send Completion handlers, and reduces the overhead of registering a chunk that has multiple segments. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-04-10xprtrdma: Reduce number of MRs created by rpcrdma_mrs_createChuck Lever
Create fewer MRs on average. Many workloads don't need as many as 32 MRs, and the transport can now quickly restock the MR free list. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-04-10xprtrdma: ->send_request returns -EAGAIN when there are no free MRsChuck Lever
Currently, when the MR free list is exhausted during marshaling, the RPC/RDMA transport places the RPC task on the delayq, which forces a wait for HZ >> 2 before the marshal and send is retried. With this change, the transport now places such an RPC task on the pending queue, and wakes it just as soon as more MRs have been created. Creating more MRs typically takes less than a millisecond, and this waking mechanism is less deadlock-prone. Moreover, the waiting RPC task is holding the transport's write lock, which blocks the transport from sending RPCs. Therefore faster recovery from MR exhaustion is desirable. This is the same mechanism that the TCP transport utilizes when handling write buffer space exhaustion. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-04-10xprtrdma: Remove xprt-specific connect cookieChuck Lever
Clean up: The generic rq_connect_cookie is sufficient to detect RPC Call retransmission. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-04-10xprtrdma: Remove arbitrary limit on initiator depthChuck Lever
Clean up: We need to check only that the value does not exceed the range of the u8 field it's going into. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-02-02xprtrdma: Fix BUG after a device removalChuck Lever
Michal Kalderon reports a BUG that occurs just after device removal: [ 169.112490] rpcrdma: removing device qedr0 for 192.168.110.146:20049 [ 169.143909] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010 [ 169.181837] IP: rpcrdma_dma_unmap_regbuf+0xa/0x60 [rpcrdma] The RPC/RDMA client transport attempts to allocate some resources on demand. Registered buffers are one such resource. These are allocated (or re-allocated) by xprt_rdma_allocate to hold RPC Call and Reply messages. A hardware resource is associated with each of these buffers, as they can be used for a Send or Receive Work Request. If a device is removed from under an NFS/RDMA mount, the transport layer is responsible for releasing all hardware resources before the device can be finally unplugged. A BUG results when the NFS mount hasn't yet seen much activity: the transport tries to release resources that haven't yet been allocated. rpcrdma_free_regbuf() already checks for this case, so just move that check to cover the DEVICE_REMOVAL case as well. Reported-by: Michal Kalderon <Michal.Kalderon@cavium.com> Fixes: bebd031866ca ("xprtrdma: Support unplugging an HCA ...") Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Tested-by: Michal Kalderon <Michal.Kalderon@cavium.com> Cc: stable@vger.kernel.org # v4.12+ Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-02-02xprtrdma: Fix calculation of ri_max_send_sgesChuck Lever
Commit 16f906d66cd7 ("xprtrdma: Reduce required number of send SGEs") introduced the rpcrdma_ia::ri_max_send_sges field. This fixes a problem where xprtrdma would not work if the device's max_sge capability was small (low single digits). At least RPCRDMA_MIN_SEND_SGES are needed for the inline parts of each RPC. ri_max_send_sges is set to this value: ia->ri_max_send_sges = max_sge - RPCRDMA_MIN_SEND_SGES; Then when marshaling each RPC, rpcrdma_args_inline uses that value to determine whether the device has enough Send SGEs to convey an NFS WRITE payload inline, or whether instead a Read chunk is required. More recently, commit ae72950abf99 ("xprtrdma: Add data structure to manage RDMA Send arguments") used the ri_max_send_sges value to calculate the size of an array, but that commit erroneously assumed ri_max_send_sges contains a value similar to the device's max_sge, and not one that was reduced by the minimum SGE count. This assumption results in the calculated size of the sendctx's Send SGE array to be too small. When the array is used to marshal an RPC, the code can write Send SGEs into the following sendctx element in that array, corrupting it. When the device's max_sge is large, this issue is entirely harmless; but it results in an oops in the provider's post_send method, if dev.attrs.max_sge is small. So let's straighten this out: ri_max_send_sges will now contain a value with the same meaning as dev.attrs.max_sge, which makes the code easier to understand, and enables rpcrdma_sendctx_create to calculate the size of the SGE array correctly. Reported-by: Michal Kalderon <Michal.Kalderon@cavium.com> Fixes: 16f906d66cd7 ("xprtrdma: Reduce required number of send SGEs") Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Tested-by: Michal Kalderon <Michal.Kalderon@cavium.com> Cc: stable@vger.kernel.org # v4.10+ Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-01-23xprtrdma: Correct some documenting commentsChuck Lever
Fix kernel-doc warnings in net/sunrpc/xprtrdma/ . net/sunrpc/xprtrdma/verbs.c:1575: warning: No description found for parameter 'count' net/sunrpc/xprtrdma/verbs.c:1575: warning: Excess function parameter 'min_reqs' description in 'rpcrdma_ep_post_extra_recv' net/sunrpc/xprtrdma/backchannel.c:288: warning: No description found for parameter 'r_xprt' net/sunrpc/xprtrdma/backchannel.c:288: warning: Excess function parameter 'xprt' description in 'rpcrdma_bc_receive_call' Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-01-23xprtrdma: Instrument allocation/release of rpcrdma_req/rep objectsChuck Lever
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-01-23xprtrdma: Add trace points to instrument QP and CQ access upcallsChuck Lever
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-01-23xprtrdma: Add trace points for connect eventsChuck Lever
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-01-23xprtrdma: Add trace points to instrument MR allocation and recoveryChuck Lever
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-01-23xprtrdma: Add trace points to instrument memory invalidationChuck Lever
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-01-23xprtrdma: Add trace points in the RPC Reply handler pathsChuck Lever
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-01-23xprtrdma: Add trace points in RPC Call transmit pathsChuck Lever
Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-01-16xprtrdma: Introduce rpcrdma_mw_unmap_and_putChuck Lever
Clean up: Code review suggested that a common bit of code can be placed into a helper function, and this gives us fewer places to stick an "I DMA unmapped something" trace point. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-01-16xprtrdma: Remove usage of "mw"Chuck Lever
Clean up: struct rpcrdma_mw was named after Memory Windows, but xprtrdma no longer supports a Memory Window registration mode. Rename rpcrdma_mw and its fields to reduce confusion and make the code more sensible to read. Renaming "mw" was suggested by Tom Talpey, the author of the original xprtrdma implementation. It's a good idea, but I haven't done this until now because it's a huge diffstat for no benefit other than code readability. However, I'm about to introduce static trace points that expose a few of xprtrdma's internal data structures. They should make sense in the trace report, and it's reasonable to treat trace points as a kernel API contract which might be difficult to change later. While I'm churning things up, two additional changes: - rename variables unhelpfully called "r" to "mr", to improve code clarity, and - rename the MR-related helper functions using the form "rpcrdma_mr_<verb>", to be consistent with other areas of the code. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-01-16xprtrdma: Replace all usage of "frmr" with "frwr"Chuck Lever
Clean up: Over time, the industry has adopted the term "frwr" instead of "frmr". The term "frwr" is now more widely recognized. For the past couple of years I've attempted to add new code using "frwr" , but there still remains plenty of older code that still uses "frmr". Replace all usage of "frmr" to avoid confusion. While we're churning code, rename variables unhelpfully called "f" to "frwr", to improve code clarity. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-01-16xprtrdma: Remove another sockaddr_storage field (cdata::addr)Chuck Lever
Save more space in struct rpcrdma_xprt by removing the redundant "addr" field from struct rpcrdma_create_data_internal. Wherever we have rpcrdma_xprt, we also have the rpc_xprt, which has a sockaddr_storage field with the same content. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-01-16xprtrdma: Initialize the xprt address string array earlierChuck Lever
This makes the address strings available for debugging messages in earlier stages of transport set up. The first benefit is to get rid of the single-use rep_remote_addr field, saving 128+ bytes in struct rpcrdma_ep. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-01-16xprtrdma: Remove ri_reminv_expectedChuck Lever
Clean up. Commit b5f0afbea4f2 ("xprtrdma: Per-connection pad optimization") should have removed this. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-01-16xprtrdma: Per-mode handling for Remote InvalidationChuck Lever
Refactoring change: Remote Invalidation is particular to the memory registration mode that is use. Use a callout instead of a generic function to handle Remote Invalidation. This gets rid of the 8-byte flags field in struct rpcrdma_mw, of which only a single bit flag has been allocated. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-01-16xprtrdma: Fix backchannel allocation of extra rpcrdma_repsChuck Lever
The backchannel code uses rpcrdma_recv_buffer_put to add new reps to the free rep list. This also decrements rb_recv_count, which spoofs the receive overrun logic in rpcrdma_buffer_get_rep. Commit 9b06688bc3b9 ("xprtrdma: Fix additional uses of spin_lock_irqsave(rb_lock)") replaced the original open-coded list_add with a call to rpcrdma_recv_buffer_put(), but then a year later, commit 05c974669ece ("xprtrdma: Fix receive buffer accounting") added rep accounting to rpcrdma_recv_buffer_put. It was an oversight to let the backchannel continue to use this function. The fix this, let's combine the "add to free list" logic with rpcrdma_create_rep. Also, do not allocate RPCRDMA_MAX_BC_REQUESTS rpcrdma_reps in rpcrdma_buffer_create and then allocate additional rpcrdma_reps in rpcrdma_bc_setup_reps. Allocating the extra reps during backchannel set-up is sufficient. Fixes: 05c974669ece ("xprtrdma: Fix receive buffer accounting") Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2017-12-15xprtrdma: Spread reply processing over more CPUsChuck Lever
Commit d8f532d20ee4 ("xprtrdma: Invoke rpcrdma_reply_handler directly from RECV completion") introduced a performance regression for NFS I/O small enough to not need memory registration. In multi- threaded benchmarks that generate primarily small I/O requests, IOPS throughput is reduced by nearly a third. This patch restores the previous level of throughput. Because workqueues are typically BOUND (in particular ib_comp_wq, nfsiod_workqueue, and rpciod_workqueue), NFS/RDMA workloads tend to aggregate on the CPU that is handling Receive completions. The usual approach to addressing this problem is to create a QP and CQ for each CPU, and then schedule transactions on the QP for the CPU where you want the transaction to complete. The transaction then does not require an extra context switch during completion to end up on the same CPU where the transaction was started. This approach doesn't work for the Linux NFS/RDMA client because currently the Linux NFS client does not support multiple connections per client-server pair, and the RDMA core API does not make it straightforward for ULPs to determine which CPU is responsible for handling Receive completions for a CQ. So for the moment, record the CPU number in the rpcrdma_req before the transport sends each RPC Call. Then during Receive completion, queue the RPC completion on that same CPU. Additionally, move all RPC completion processing to the deferred handler so that even RPCs with simple small replies complete on the CPU that sent the corresponding RPC Call. Fixes: d8f532d20ee4 ("xprtrdma: Invoke rpcrdma_reply_handler ...") Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2017-11-17xprtrdma: Update copyright noticesChuck Lever
Credit work contributed by Oracle engineers since 2014. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2017-11-17xprtrdma: Remove include for linux/prefetch.hChuck Lever
Clean up. This include should have been removed by commit 23826c7aeac7 ("xprtrdma: Serialize credit accounting again"). Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Reviewed-by: Devesh Sharma <devesh.sharma@broadcom.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2017-11-17xprtrdma: Put Send CQ in IB_POLL_WORKQUEUE modeChuck Lever
Lift the Send and LocalInv completion handlers out of soft IRQ mode to make room for other work. Also, move the Send CQ to a different CPU than the CPU where the Receive CQ is running, for improved scalability. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Reviewed-by: Devesh Sharma <devesh.sharma@broadcom.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2017-11-17xprtrdma: Remove atomic send completion countingChuck Lever
The sendctx circular queue now guarantees that xprtrdma cannot overflow the Send Queue, so remove the remaining bits of the original Send WQE counting mechanism. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2017-11-17xprtrdma: RPC completion should wait for Send completionChuck Lever
When an RPC Call includes a file data payload, that payload can come from pages in the page cache, or a user buffer (for direct I/O). If the payload can fit inline, xprtrdma includes it in the Send using a scatter-gather technique. xprtrdma mustn't allow the RPC consumer to re-use the memory where that payload resides before the Send completes. Otherwise, the new contents of that memory would be exposed by an HCA retransmit of the Send operation. So, block RPC completion on Send completion, but only in the case where a separate file data payload is part of the Send. This prevents the reuse of that memory while it is still part of a Send operation without an undue cost to other cases. Waiting is avoided in the common case because typically the Send will have completed long before the RPC Reply arrives. These days, an RPC timeout will trigger a disconnect, which tears down the QP. The disconnect flushes all waiting Sends. This bounds the amount of time the reply handler has to wait for a Send completion. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2017-11-17xprtrdma: Add a field of bit flags to struct rpcrdma_reqChuck Lever
We have one boolean flag in rpcrdma_req today. I'd like to add more flags, so convert that boolean to a bit flag. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2017-11-17xprtrdma: Add data structure to manage RDMA Send argumentsChuck Lever
Problem statement: Recently Sagi Grimberg <sagi@grimberg.me> observed that kernel RDMA- enabled storage initiators don't handle delayed Send completion correctly. If Send completion is delayed beyond the end of a ULP transaction, the ULP may release resources that are still being used by the HCA to complete a long-running Send operation. This is a common design trait amongst our initiators. Most Send operations are faster than the ULP transaction they are part of. Waiting for a completion for these is typically unnecessary. Infrequently, a network partition or some other problem crops up where an ordering problem can occur. In NFS parlance, the RPC Reply arrives and completes the RPC, but the HCA is still retrying the Send WR that conveyed the RPC Call. In this case, the HCA can try to use memory that has been invalidated or DMA unmapped, and the connection is lost. If that memory has been re-used for something else (possibly not related to NFS), and the Send retransmission exposes that data on the wire. Thus we cannot assume that it is safe to release Send-related resources just because a ULP reply has arrived. After some analysis, we have determined that the completion housekeeping will not be difficult for xprtrdma: - Inline Send buffers are registered via the local DMA key, and are already left DMA mapped for the lifetime of a transport connection, thus no additional handling is necessary for those - Gathered Sends involving page cache pages _will_ need to DMA unmap those pages after the Send completes. But like inline send buffers, they are registered via the local DMA key, and thus will not need to be invalidated In addition, RPC completion will need to wait for Send completion in the latter case. However, nearly always, the Send that conveys the RPC Call will have completed long before the RPC Reply arrives, and thus no additional latency will be accrued. Design notes: In this patch, the rpcrdma_sendctx object is introduced, and a lock-free circular queue is added to manage a set of them per transport. The RPC client's send path already prevents sending more than one RPC Call at the same time. This allows us to treat the consumer side of the queue (rpcrdma_sendctx_get_locked) as if there is a single consumer thread. The producer side of the queue (rpcrdma_sendctx_put_locked) is invoked only from the Send completion handler, which is a single thread of execution (soft IRQ). The only care that needs to be taken is with the tail index, which is shared between the producer and consumer. Only the producer updates the tail index. The consumer compares the head with the tail to ensure that the a sendctx that is in use is never handed out again (or, expressed more conventionally, the queue is empty). When the sendctx queue empties completely, there are enough Sends outstanding that posting more Send operations can result in a Send Queue overflow. In this case, the ULP is told to wait and try again. This introduces strong Send Queue accounting to xprtrdma. As a final touch, Jason Gunthorpe <jgunthorpe@obsidianresearch.com> suggested a mechanism that does not require signaling every Send. We signal once every N Sends, and perform SGE unmapping of N Send operations during that one completion. Reported-by: Sagi Grimberg <sagi@grimberg.me> Suggested-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com> Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2017-11-17xprtrdma: Decode credits field in rpcrdma_reply_handlerChuck Lever
We need to decode and save the incoming rdma_credits field _after_ we know that the direction of the message is "forward direction Reply". Otherwise, the credits value in reverse direction Calls is also used to update the forward direction credits. It is safe to decode the rdma_credits field in rpcrdma_reply_handler now that rpcrdma_reply_handler is single-threaded. Receives complete in the same order as they were sent on the NFS server. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2017-11-17xprtrdma: Invoke rpcrdma_reply_handler directly from RECV completionChuck Lever
I noticed that the soft IRQ thread looked pretty busy under heavy I/O workloads. perf suggested one area that was expensive was the queue_work() call in rpcrdma_wc_receive. That gave me some ideas. Instead of scheduling a separate worker to process RPC Replies, promote the Receive completion handler to IB_POLL_WORKQUEUE, and invoke rpcrdma_reply_handler directly. Note that the poll workqueue is single-threaded. In order to keep memory invalidation from serializing all RPC Replies, handle any necessary invalidation tasks in a separate multi-threaded workqueue. This provides a two-tier scheme, similar to OS I/O interrupt handlers: A fast interrupt handler that schedules the slow handler and re-enables the interrupt, and a slower handler that is invoked for any needed heavy lifting. Benefits include: - One less context switch for RPCs that don't register memory - Receive completion handling is moved out of soft IRQ context to make room for other users of soft IRQ - The same CPU core now DMA syncs and XDR decodes the Receive buffer Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2017-09-05xprtrdma: Use xprt_pin_rqst in rpcrdma_reply_handlerChuck Lever
Adopt the use of xprt_pin_rqst to eliminate contention between Call-side users of rb_lock and the use of rb_lock in rpcrdma_reply_handler. This replaces the mechanism introduced in 431af645cf66 ("xprtrdma: Fix client lock-up after application signal fires"). Use recv_lock to quickly find the completing rqst, pin it, then drop the lock. At that point invalidation and pull-up of the Reply XDR can be done. Both are often expensive operations. Finally, take recv_lock again to signal completion to the RPC layer. It also protects adjustment of "cwnd". This greatly reduces the amount of time a lock is held by the reply handler. Comparing lock_stat results shows a marked decrease in contention on rb_lock and recv_lock. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> [trond.myklebust@primarydata.com: Remove call to rpcrdma_buffer_put() from the "out_norqst:" path in rpcrdma_reply_handler.] Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>