An RPC can terminate before its reply arrives, if a credential
problem or a soft timeout occurs. After this happens, xprtrdma
reports it is out of Receive buffers.
A Receive buffer is posted before each RPC is sent, and returned to
the buffer pool when a reply is received. If no reply is received
for an RPC, that Receive buffer remains posted. But xprtrdma tries
to post another when the next RPC is sent.
If this happens a few dozen times, there are no receive buffers left
to be posted at send time. I don't see a way for a transport
connection to recover at that point, and it will spit warnings and
unnecessarily delay RPCs on occasion for its remaining lifetime.
Commit 1e465fd4ff ("xprtrdma: Replace send and receive arrays")
removed a little bit of logic to detect this case and not provide
a Receive buffer so no more buffers are posted, and then transport
operation continues correctly. We didn't understand what that logic
did, and it wasn't commented, so it was removed as part of the
overhaul to support backchannel requests.
Restore it, but be wary of the need to keep extra Receives posted
to deal with backchannel requests.
Fixes: 1e465fd4ff ("xprtrdma: Replace send and receive arrays")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Receive buffer exhaustion, if it were to actually occur, would be
catastrophic. However, when there are no reply buffers to post, that
means all of them have already been posted and are waiting for
incoming replies. By design, there can never be more RPCs in flight
than there are available receive buffers.
A receive buffer can be left posted after an RPC exits without a
received reply; say, due to a credential problem or a soft timeout.
This does not result in fewer posted receive buffers than there are
pending RPCs, and there is already logic in xprtrdma to deal
appropriately with this case.
It also looks like the "+ 2" that was removed was accidentally
accommodating the number of extra receive buffers needed for
receiving backchannel requests. That will need to be addressed by
another patch.
Fixes: 3d4cf35bd4 ("xprtrdma: Reply buffer exhaustion can be...")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Direct data placement is not allowed when using flavors that
guarantee integrity or privacy. When such security flavors are in
effect, don't allow the use of Read and Write chunks for moving
individual data items. All messages larger than the inline threshold
are sent via Long Call or Long Reply.
On my systems (CX-3 Pro on FDR), for small I/O operations, the use
of Long messages adds only around 5 usecs of latency in each
direction.
Note that when integrity or encryption is used, the host CPU touches
every byte in these messages. Even if it could be used, data
movement offload doesn't buy much in this case.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
fixup_copy_count should count only the number of bytes copied to the
page list. The head and tail are now always handled without a data
copy.
And the debugging at the end of rpcrdma_inline_fixup() is also no
longer necessary, since copy_len will be non-zero when there is reply
data in the tail (a normal and valid case).
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Now that rpcrdma_inline_fixup() updates only two fields in
rq_rcv_buf, a full memcpy of that structure to rq_private_buf is
unwarranted. Updating rq_private_buf fields only where needed also
better documents what is going on.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
While trying NFSv4.0/RDMA with sec=krb5p, I noticed small NFS READ
operations failed. After the client unwrapped the NFS READ reply
message, the NFS READ XDR decoder was not able to decode the reply.
The message was "Server cheating in reply", with the reported
number of received payload bytes being zero. Applications reported
a read(2) that returned -1/EIO.
The problem is rpcrdma_inline_fixup() sets the tail.iov_len to zero
when the incoming reply fits entirely in the head iovec. The zero
tail.iov_len confused xdr_buf_trim(), which then mangled the actual
reply data instead of simply removing the trailing GSS checksum.
As near as I can tell, RPC transports are not supposed to update the
head.iov_len, page_len, or tail.iov_len fields in the receive XDR
buffer when handling an incoming RPC reply message. These fields
contain the length of each component of the XDR buffer, and hence
the maximum number of bytes of reply data that can be stored in each
XDR buffer component. I've concluded this because:
- This is how xdr_partial_copy_from_skb() appears to behave
- rpcrdma_inline_fixup() already does not alter page_len
- call_decode() compares rq_private_buf and rq_rcv_buf and WARNs
if they are not exactly the same
Unfortunately, as soon as I tried the simple fix to just remove the
line that sets tail.iov_len to zero, I saw that the logic that
appends the implicit Write chunk pad inline depends on inline_fixup
setting tail.iov_len to zero.
To address this, re-organize the tail iovec handling logic to use
the same approach as with the head iovec: simply point tail.iov_base
to the correct bytes in the receive buffer.
While I remember all this, write down the conclusion in documenting
comments.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
When the remaining length of an incoming reply is longer than the
XDR buf's page_len, switch over to the tail iovec instead of
copying more than page_len bytes into the page list.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Currently, all three chunk list encoders each use a portion of the
one rl_segments array in rpcrdma_req. This is because the MWs for
each chunk list were preserved in rl_segments so that ro_unmap could
find and invalidate them after the RPC was complete.
However, now that MWs are placed on a per-req linked list as they
are registered, there is no longer any information in rpcrdma_mr_seg
that is shared between ro_map and ro_unmap_{sync,safe}, and thus
nothing in rl_segments needs to be preserved after
rpcrdma_marshal_req is complete.
Thus the rl_segments array can be used now just for the needs of
each rpcrdma_convert_iovs call. Once each chunk list is encoded, the
next chunk list encoder is free to re-use all of rl_segments.
This means all three chunk lists in one RPC request can now each
encode a full size data payload with no increase in the size of
rl_segments.
This is a key requirement for Kerberos support, since both the Call
and Reply for a single RPC transaction are conveyed via Long
messages (RDMA Read/Write). Both can be large.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Instead of placing registered MWs sparsely into the rl_segments
array, place these MWs on a per-req list.
ro_unmap_{sync,safe} can then simply pull those MWs off the list
instead of walking through the array.
This change significantly reduces the size of struct rpcrdma_req
by removing nsegs and rl_mw from every array element.
As an additional clean-up, chunk co-ordinates are returned in the
"*mw" output argument so they are no longer needed in every
array element.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Instead of leaving orphaned MRs to be released when the transport
is destroyed, release them immediately. The MR free list can now be
replenished if it becomes exhausted.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Frequent MR list exhaustion can impact I/O throughput, so enough MRs
are always created during transport set-up to prevent running out.
This means more MRs are created than most workloads need.
Commit 94f58c58c0 ("xprtrdma: Allow Read list and Reply chunk
simultaneously") introduced support for sending two chunk lists per
RPC, which consumes more MRs per RPC.
Instead of trying to provision more MRs, introduce a mechanism for
allocating MRs on demand. A few MRs are allocated during transport
set-up to kick things off.
This significantly reduces the average number of MRs per transport
while allowing the MR count to grow for workloads or devices that
need more MRs.
FRWR with mlx4 allocated almost 400 MRs per transport before this
patch. Now it starts with 32.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Clean up, based on code audit: Remove the possibility that the
chunk list XDR encoders can return zero, which would be interpreted
as a NULL.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Commit c93c62231c ("xprtrdma: Disconnect on registration failure")
added a disconnect for some RPC marshaling failures. This is needed
only in a handful of cases, but it was triggering for simple stuff
like temporary resource shortages. Try to straighten this out.
Fix up the lower layers so they don't return -ENOMEM or other error
codes that the RPC client's FSM doesn't explicitly recognize.
Also fix up the places in the send_request path that do want a
disconnect. For example, when ib_post_send or ib_post_recv fail,
this is a sign that there is a send or receive queue resource
miscalculation. That should be rare, and is a sign of a software
bug. But xprtrdma can recover: disconnect to reset the transport and
start over.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Not having an rpcrdma_rep at call_allocate time can be a problem.
It means that send_request can't post a receive buffer to catch
the RPC's reply. Possible consequences are RPC timeouts or even
transport deadlock.
Instead of allowing an RPC to proceed if an rpcrdma_rep is
not available, return NULL to force call_allocate to wait and
try again.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Clean up: ALLPHYSICAL is gone and FMR has been converted to use
scatterlists. There are no more users of these functions.
This patch shrinks the size of struct rpcrdma_req by about 3500
bytes on x86_64. There is one of these structs for each RPC credit
(128 credits per transport connection).
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
No HCA or RNIC in the kernel tree requires the use of ALLPHYSICAL.
ALLPHYSICAL advertises in the clear on the network fabric an R_key
that is good for all of the client's memory. No known exploit
exists, but theoretically any user on the server can use that R_key
on the client's QP to read or update any part of the client's memory.
ALLPHYSICAL exposes the client to server bugs, including:
o base/bounds errors causing data outside the i/o buffer to be
accessed
o RDMA access after reply causing data corruption and/or integrity
fail
ALLPHYSICAL can't protect application memory regions from server
update after a local signal or soft timeout has terminated an RPC.
ALLPHYSICAL chunks are no larger than a page. Special cases to
handle small chunks and long chunk lists have been a source of
implementation complexity and bugs.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Based on code audit.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
I found that commit ead3f26e35 ("xprtrdma: Add ro_unmap_safe
memreg method"), which introduces ro_unmap_safe, never wired up the
FMR recovery worker.
The FMR and FRWR recovery work queues both do the same thing.
Instead of setting up separate individual work queues for this,
schedule a delayed worker to deal with them, since recovering MRs is
not performance-critical.
Fixes: ead3f26e35 ("xprtrdma: Add ro_unmap_safe memreg method")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
The use of a scatterlist for handling DMA mapping and unmapping
was recently introduced in frwr_ops.c in commit 4143f34e01
("xprtrdma: Port to new memory registration API"). That commit did
not make a similar update to xprtrdma's FMR support because the
core ib_map_phys_fmr() and ib_unmap_fmr() APIs have not been changed
to take a scatterlist argument.
However, FMR still needs to do DMA mapping and unmapping. It appears
that RDS, for example, uses a scatterlist for this, then builds the
DMA addr array for the ib_map_phys_fmr call separately. I see that
SRP also utilizes a scatterlist for DMA mapping. xprtrdma can do
something similar.
This modernization is used immediately to properly defer DMA
unmapping during fmr_unmap_safe (a FIXME). It separates the DMA
unmapping coordinates from the rl_segments array. This array, being
part of an rpcrdma_req, is always re-used immediately when an RPC
exits. A scatterlist is allocated in memory independent of the
rl_segments array, so it can be preserved indefinitely (ie, until
the MR invalidation and DMA unmapping can actually be done by a
worker thread).
The FRWR and FMR DMA mapping code are slightly different from each
other now, and will diverge further when the "Check for holes" logic
can be removed from FRWR (support for SG_GAP MRs). So I chose not to
create helpers for the common-looking code.
Fixes: ead3f26e35 ("xprtrdma: Add ro_unmap_safe memreg method")
Suggested-by: Sagi Grimberg <sagi@lightbits.io>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Clean up: Use the same naming convention used in other
RPC/RDMA-related data structures.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Clean up: Moving these helpers in a separate patch makes later
patches more readable.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Clean up: FMR is about to replace the rpcrdma_map_one code with
scatterlists. Move the scatterlist fields out of the FRWR-specific
union and into the generic part of rpcrdma_mw.
One minor change: -EIO is now returned if FRWR registration fails.
The RPC is terminated immediately, since the problem is likely due
to a software bug, thus retrying likely won't help.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
ib_unmap_fmr() takes a list of FMRs to unmap. However, it does not
remove the FMRs from this list as it processes them. Other
ib_unmap_fmr() call sites are careful to remove FMRs from the list
after ib_unmap_fmr() returns.
Since commit 7c7a5390dc ("xprtrdma: Add ro_unmap_sync method for FMR")
fmr_op_unmap_sync passes more than one FMR to ib_unmap_fmr(), but
it didn't bother to remove the FMRs from that list once the call was
complete.
I've noticed some instability that could be related to list
tangling by the new fmr_op_unmap_sync() logic. In an abundance
of caution, add some defensive logic to clean up properly after
ib_unmap_fmr().
Fixes: 7c7a5390dc ("xprtrdma: Add ro_unmap_sync method for FMR")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Highlights include:
Features:
- Add support for the NFS v4.2 COPY operation
- Add support for NFS/RDMA over IPv6
Bugfixes and cleanups:
- Avoid race that crashes nfs_init_commit()
- Fix oops in callback path
- Fix LOCK/OPEN race when unlinking an open file
- Choose correct stateids when using delegations in setattr, read and write
- Don't send empty SETATTR after OPEN_CREATE
- xprtrdma: Prevent server from writing a reply into memory client has released
- xprtrdma: Support using Read list and Reply chunk in one RPC call
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Merge tag 'nfs-for-4.7-1' of git://git.linux-nfs.org/projects/anna/linux-nfs
Pull NFS client updates from Anna Schumaker:
"Highlights include:
Features:
- Add support for the NFS v4.2 COPY operation
- Add support for NFS/RDMA over IPv6
Bugfixes and cleanups:
- Avoid race that crashes nfs_init_commit()
- Fix oops in callback path
- Fix LOCK/OPEN race when unlinking an open file
- Choose correct stateids when using delegations in setattr, read and
write
- Don't send empty SETATTR after OPEN_CREATE
- xprtrdma: Prevent server from writing a reply into memory client
has released
- xprtrdma: Support using Read list and Reply chunk in one RPC call"
* tag 'nfs-for-4.7-1' of git://git.linux-nfs.org/projects/anna/linux-nfs: (61 commits)
pnfs: pnfs_update_layout needs to consider if strict iomode checking is on
nfs/flexfiles: Use the layout segment for reading unless it a IOMODE_RW and reading is disabled
nfs/flexfiles: Helper function to detect FF_FLAGS_NO_READ_IO
nfs: avoid race that crashes nfs_init_commit
NFS: checking for NULL instead of IS_ERR() in nfs_commit_file()
pnfs: make pnfs_layout_process more robust
pnfs: rework LAYOUTGET retry handling
pnfs: lift retry logic from send_layoutget to pnfs_update_layout
pnfs: fix bad error handling in send_layoutget
flexfiles: add kerneldoc header to nfs4_ff_layout_prepare_ds
flexfiles: remove pointless setting of NFS_LAYOUT_RETURN_REQUESTED
pnfs: only tear down lsegs that precede seqid in LAYOUTRETURN args
pnfs: keep track of the return sequence number in pnfs_layout_hdr
pnfs: record sequence in pnfs_layout_segment when it's created
pnfs: don't merge new ff lsegs with ones that have LAYOUTRETURN bit set
pNFS/flexfiles: When initing reads or writes, we might have to retry connecting to DSes
pNFS/flexfiles: When checking for available DSes, conditionally check for MDS io
pNFS/flexfile: Fix erroneous fall back to read/write through the MDS
NFS: Reclaim writes via writepage are opportunistic
NFSv4: Use the right stateid for delegations in setattr, read and write
...
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Merge tag 'nfsd-4.7' of git://linux-nfs.org/~bfields/linux
Pull nfsd updates from Bruce Fields:
"A very quiet cycle for nfsd, mainly just an RDMA update from Chuck
Lever"
* tag 'nfsd-4.7' of git://linux-nfs.org/~bfields/linux:
sunrpc: fix stripping of padded MIC tokens
svcrpc: autoload rdma module
svcrdma: Generalize svc_rdma_xdr_decode_req()
svcrdma: Eliminate code duplication in svc_rdma_recvfrom()
svcrdma: Drain QP before freeing svcrdma_xprt
svcrdma: Post Receives only for forward channel requests
svcrdma: Remove superfluous line from rdma_read_chunks()
svcrdma: svc_rdma_put_context() is invoked twice in Send error path
svcrdma: Do not add XDR padding to xdr_buf page vector
svcrdma: Support IPv6 with NFS/RDMA
nfsd: handle seqid wraparound in nfsd4_preprocess_layout_stateid
Remove unnecessary allocation
Clean up.
After "xprtrdma: Remove ro_unmap() from all registration modes",
there are no longer any sites that take rpcrdma_ia::qplock for read.
The one site that takes it for write is always single-threaded. It
is safe to remove it.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
In a cluster failover scenario, it is desirable for the client to
attempt to reconnect quickly, as an alternate NFS server is already
waiting to take over for the down server. The client can't see that
a server IP address has moved to a new server until the existing
connection is gone.
For fabrics and devices where it is meaningful, set a definite upper
bound on the amount of time before it is determined that a
connection is no longer valid. This allows the RPC client to detect
connection loss in a timely matter, then perform a fresh resolution
of the server GUID in case it has changed (cluster failover).
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Clean up: The ro_unmap method is no longer used.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
There needs to be a safe method of releasing registered memory
resources when an RPC terminates. Safe can mean a number of things:
+ Doesn't have to sleep
+ Doesn't rely on having a QP in RTS
ro_unmap_safe will be that safe method. It can be used in cases
where synchronous memory invalidation can deadlock, or needs to have
an active QP.
The important case is fencing an RPC's memory regions after it is
signaled (^C) and before it exits. If this is not done, there is a
window where the server can write an RPC reply into memory that the
client has released and re-used for some other purpose.
Note that this is a full solution for FRWR, but FMR and physical
still have some gaps where a particularly bad server can wreak
some havoc on the client. These gaps are not made worse by this
patch and are expected to be exceptionally rare and timing-based.
They are noted in documenting comments.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Separate the DMA unmap operation from freeing the MW. In a
subsequent patch they will not always be done at the same time,
and they are not related operations (except by order; freeing
the MW must be the last step during invalidation).
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
In a subsequent patch, the fr_xprt and fr_worker fields will be
needed by another memory registration mode. Move them into the
generic rpcrdma_mw structure that wraps struct rpcrdma_frmr.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Maintain the order of invalidation and DMA unmapping when doing
a background MR reset.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
frwr_op_unmap_sync() is now invoked in a workqueue context, the same
as __frwr_queue_recovery(). There's no need to defer MR reset if
posting LOCAL_INV MRs fails.
This means that even when ib_post_send() fails (which should occur
very rarely) the invalidation and DMA unmapping steps are still done
in the correct order.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Move the the I/O direction field from rpcrdma_mr_seg into the
rpcrdma_frmr.
This makes it possible to DMA-unmap the frwr long after an RPC has
exited and its rpcrdma_mr_seg array has been released and re-used.
This might occur if an RPC times out while waiting for a new
connection to be established.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Clean up: Follow same naming convention as other fields in struct
rpcrdma_frwr.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Clean up: Replace rpcrdma_flush_cqs() and rpcrdma_clean_cqs() with
the new ib_drain_qp() API.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-By: Leon Romanovsky <leonro@mellanox.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
rpcrdma_create_chunks() has been replaced, and can be removed.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
rpcrdma_marshal_req() makes a simplifying assumption: that NFS
operations with large Call messages have small Reply messages, and
vice versa. Therefore with RPC-over-RDMA, only one chunk type is
ever needed for each Call/Reply pair, because one direction needs
chunks, the other direction will always fit inline.
In fact, this assumption is asserted in the code:
if (rtype != rpcrdma_noch && wtype != rpcrdma_noch) {
dprintk("RPC: %s: cannot marshal multiple chunk lists\n",
__func__);
return -EIO;
}
But RPCGSS_SEC breaks this assumption. Because krb5i and krb5p
perform data transformation on RPC messages before they are
transmitted, direct data placement techniques cannot be used, thus
RPC messages must be sent via a Long call in both directions.
All such calls are sent with a Position Zero Read chunk, and all
such replies are handled with a Reply chunk. Thus the client must
provide every Call/Reply pair with both a Read list and a Reply
chunk.
Without any special security in effect, NFSv4 WRITEs may now also
use the Read list and provide a Reply chunk. The marshal_req
logic was preventing that, meaning an NFSv4 WRITE with a large
payload that included a GETATTR result larger than the inline
threshold would fail.
The code that encodes each chunk list is now completely contained in
its own function. There is some code duplication, but the trade-off
is that the overall logic should be more clear.
Note that all three chunk lists now share the rl_segments array.
Some additional per-req accounting is necessary to track this
usage. For the same reasons that the above simplifying assumption
has held true for so long, I don't expect more array elements are
needed at this time.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Update documenting comments to reflect code changes over the past
year.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Avoid the latency and interrupt overhead of registering a Write
chunk when handling NFS READ requests of a few hundred bytes or
less.
This change does not interoperate with Linux NFS/RDMA servers
that do not have commit 9d11b51ce7 ('svcrdma: Fix send_reply()
scatter/gather set-up'). Commit 9d11b51ce7 was introduced in v4.3,
and is included in 4.2.y, 4.1.y, and 3.18.y.
Oracle bug 22925946 has been filed to request that the above fix
be included in the Oracle Linux UEK4 NFS/RDMA server.
Red Hat bugzillas 1327280 and 1327554 have been filed to request
that RHEL NFS/RDMA server backports include the above fix.
Workaround: Replace the "proto=rdma,port=20049" mount options
with "proto=tcp" until commit 9d11b51ce7 is applied to your
NFS server.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
When deciding whether to send a Call inline, rpcrdma_marshal_req
doesn't take into account header bytes consumed by chunk lists.
This results in Call messages on the wire that are sometimes larger
than the inline threshold.
Likewise, when a Write list or Reply chunk is in play, the server's
reply has to emit an RDMA Send that includes a larger-than-minimal
RPC-over-RDMA header.
The actual size of a Call message cannot be estimated until after
the chunk lists have been registered. Thus the size of each
RPC-over-RDMA header can be estimated only after chunks are
registered; but the decision to register chunks is based on the size
of that header. Chicken, meet egg.
The best a client can do is estimate header size based on the
largest header that might occur, and then ensure that inline content
is always smaller than that.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Send buffer space is shared between the RPC-over-RDMA header and
an RPC message. A large RPC-over-RDMA header means less space is
available for the associated RPC message, which then has to be
moved via an RDMA Read or Write.
As more segments are added to the chunk lists, the header increases
in size. Typical modern hardware needs only a few segments to
convey the maximum payload size, but some devices and registration
modes may need a lot of segments to convey data payload. Sometimes
so many are needed that the remaining space in the Send buffer is
not enough for the RPC message. Sending such a message usually
fails.
To ensure a transport can always make forward progress, cap the
number of RDMA segments that are allowed in chunk lists. This
prevents less-capable devices and memory registrations from
consuming a large portion of the Send buffer by reducing the
maximum data payload that can be conveyed with such devices.
For now I choose an arbitrary maximum of 8 RDMA segments. This
allows a maximum size RPC-over-RDMA header to fit nicely in the
current 1024 byte inline threshold with over 700 bytes remaining
for an inline RPC message.
The current maximum data payload of NFS READ or WRITE requests is
one megabyte. To convey that payload on a client with 4KB pages,
each chunk segment would need to handle 32 or more data pages. This
is well within the capabilities of FMR. For physical registration,
the maximum payload size on platforms with 4KB pages is reduced to
32KB.
For FRWR, a device's maximum page list depth would need to be at
least 34 to support the maximum 1MB payload. A device with a smaller
maximum page list depth means the maximum data payload is reduced
when using that device.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Currently the sysctls that allow setting the inline threshold allow
any value to be set.
Small values only make the transport run slower. The default 1KB
setting is as low as is reasonable. And the logic that decides how
to divide a Send buffer between RPC-over-RDMA header and RPC message
assumes (but does not check) that the lower bound is not crazy (say,
57 bytes).
Send and receive buffers share a page with some control information.
Values larger than about 3KB can't be supported, currently.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
RPC-over-RDMA transports have a limit on how large a backward
direction (backchannel) RPC message can be. Ensure that the NFSv4.x
CREATE_SESSION operation advertises this limit to servers.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Clean up: Pass in just the piece of the svc_rqst that is needed
here.
While we're in the area, add an informative documenting comment.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
If the server has forced a disconnect, the associated QP has not
been moved to the Error state, and thus Receives are still posted.
Ensure Receives (and any other outstanding WRs) are drained to
release resources that can be freed during teardown of the
svcrdma_xprt.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Since backward direction support was added, the rq_depth was
increased to accommodate both forward and backward Receives.
But only forward Receives need to be posted after a connection
has been accepted. Receives for backward replies are posted as
needed by svc_rdma_bc_sendto().
This doesn't break anything, but it means some resources are
wasted.
Fixes: 03fe993153 ('svcrdma: Define maximum number of ...')
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
