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

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

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

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

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

This removes some code duplication, since both functions were doing the
same thing.
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

We need to use the custom rpc_task_setup here to set the
RPC_TASK_NO_ROUND_ROBIN flag on the RPC call.
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

An async call followed by an rpc_wait_for_completion() is basically the
same as a synchronous call, so we can use nfs4_call_sync_custom() to
keep our custom callback ops and the RPC_TASK_NO_ROUND_ROBIN flag.
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

We do this to set the RPC_TASK_NO_ROUND_ROBIN flag in the task_setup
structure
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

Rather than running the task manually
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

There are a few cases where we need to manually configure the
rpc_task_setup structure to get the behavior we want.
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

In nfs4_try_migration(), if nfs4_begin_drain_session() fails, the
previously allocated 'page' and 'locations' are not deallocated, leading to
memory leaks. To fix this issue, go to the 'out' label to free 'page' and
'locations' before returning the error.
Signed-off-by: Wenwen Wang <wenwen@cs.uga.edu>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Found via code review.

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

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

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

I've heard rumors of an NFS/RDMA server implementation that has a
default credit limit of 1024. The client's default setting remains
at 128.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

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

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

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

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

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

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

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

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

Micro-optimization: For xdr_commit_encode call sites in
net/sunrpc/xdr.c, eliminate the extra calling sequence.  On my
client, this change saves about a microsecond for every 30 calls
to xdr_reserve_space().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

Clean up: commit c544577d ("SUNRPC: Clean up transport write
space handling") appears to have removed the last caller of
rpc_wake_up_queued_task_on_wq().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

In encode_attrs(), there is an if statement on line 1145 to check
whether label is NULL:
    if (label && (attrmask[2] & FATTR4_WORD2_SECURITY_LABEL))

When label is NULL, it is used on lines 1178-1181:
    *p++ = cpu_to_be32(label->lfs);
    *p++ = cpu_to_be32(label->pi);
    *p++ = cpu_to_be32(label->len);
    p = xdr_encode_opaque_fixed(p, label->label, label->len);

To fix these bugs, label is checked before being used.

These bugs are found by a static analysis tool STCheck written by us.
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

Pull MTD fix from Richard Weinberger:
 "A single fix for MTD to correctly set the spi-nor WP pin"

* tag 'fixes-for-5.3-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux:
  mtd: spi-nor: Fix the disabling of write protection at init

Pull btrfs fixes from David Sterba:
 "Two fixes that popped up during testing:

   - fix for sysfs-related code that adds/removes block groups, warnings
     appear during several fstests in connection with sysfs updates in
     5.3, the fix essentially replaces a workaround with scope NOFS and
     applies to 5.2-based branch too

   - add sanity check of trim range"

* tag 'for-5.3-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: trim: Check the range passed into to prevent overflow
  Btrfs: fix sysfs warning and missing raid sysfs directories

Pull x86 fixes from Thomas Gleixner:
 "A set of fixes for x86:

   - Fix the inconsistent error handling in the umwait init code

   - Rework the boot param zeroing so gcc9 stops complaining about out
     of bound memset. The resulting source code is actually more sane to
     read than the smart solution we had

   - Maintainers update so Tony gets involved when Intel models are
     added

   - Some more fallthrough fixes"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/boot: Save fields explicitly, zero out everything else
  MAINTAINERS, x86/CPU: Tony Luck will maintain asm/intel-family.h
  x86/fpu/math-emu: Address fallthrough warnings
  x86/apic/32: Fix yet another implicit fallthrough warning
  x86/umwait: Fix error handling in umwait_init()

Pull EFI fix from Thomas Gleixner:
 "A single fix for a EFI mixed mode regression caused by recent rework
  which did not take the firmware bitwidth into account"

* 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  efi-stub: Fix get_efi_config_table on mixed-mode setups

Pull SPDX fixes from Greg KH:
 "Here are four small SPDX fixes for 5.3-rc5.

  A few style fixes for some SPDX comments, added an SPDX tag for one
  file, and fix up some GPL boilerplate for another file.

  All of these have been in linux-next for a few weeks with no reported
  issues (they are comment changes only, so that's to be expected...)"

* tag 'spdx-5.3-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx:
  i2c: stm32: Use the correct style for SPDX License Identifier
  intel_th: Use the correct style for SPDX License Identifier
  coccinelle: api/atomic_as_refcounter: add SPDX License Identifier
  kernel/configs: Replace GPL boilerplate code with SPDX identifier

Pull char/misc driver fixes from Greg KH:
 "Here are some small char and misc driver fixes for 5.3-rc5.

  These are two different subsystems needing some fixes, the habanalabs
  driver which is has some more big endian fixes for problems found. The
  other are some small soundwire fixes, including some Kconfig
  dependencies needed to resolve reported build errors.

  All of these have been in linux-next this week with no reported
  issues"

* tag 'char-misc-5.3-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  misc: xilinx-sdfec: fix dependency and build error
  habanalabs: fix device IRQ unmasking for BE host
  habanalabs: fix endianness handling for internal QMAN submission
  habanalabs: fix completion queue handling when host is BE
  habanalabs: fix endianness handling for packets from user
  habanalabs: fix DRAM usage accounting on context tear down
  habanalabs: Avoid double free in error flow
  soundwire: fix regmap dependencies and align with other serial links
  soundwire: cadence_master: fix definitions for INTSTAT0/1
  soundwire: cadence_master: fix register definition for SLAVE_STATE

Pull staging/IIO fixes from Greg KH:
 "Here are four small staging and iio driver fixes for 5.3-rc5

  Two are for the dt3000 comedi driver for some reported problems found
  in that codebase, and two are some small iio fixes.

  All of these have been in linux-next this week with no reported
  issues"

* tag 'staging-5.3-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  staging: comedi: dt3000: Fix rounding up of timer divisor
  staging: comedi: dt3000: Fix signed integer overflow 'divider * base'
  iio: adc: max9611: Fix temperature reading in probe
  iio: frequency: adf4371: Fix output frequency setting