The NFS client code (nfsrpc_readdir() and nfsrpc_readdirplus()) wasn't
filling in parts of the readdir reply, such as d_pad[01] and the bytes
at the end of d_name within d_reclen. As such, data left in a buffer cache
block could be leaked to userland in the readdir reply.
This patch makes sure all of the data is filled in.
Reported by: Thomas Barabosch, Fraunhofer FKIE
Reviewed by: kib, markj
MFC after: 2 weeks
Prior to this patch, nfs_advlock() did NFSVOPUNLOCK(); return (error);
in many places. This patch replaces these code sequenences with a "goto out;"
and does the NFSVOPUNLOCK(); return (error); at the end of the function
in order to make the vnode locking simpler.
This patch does not change the semantics of nfs_advlock().
Suggested by: kib
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D17853
Leave ptrace(2) alone for the moment as it's defined to take a caddr_t.
Reviewed by: kib
Obtained from: CheriBSD
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D17852
This will enable callers to take const paths as part of syscall
decleration improvements.
Where doing so is easy and non-distruptive carry the const through
implementations. In UFS the value is passed to an interface that must
take non-const values. In ZFS, const poisoning would touch code shared
with upstream and it's not worth adding diffs.
Bump __FreeBSD_version for external API consumers.
Reviewed by: kib (prior version)
Obtained from: CheriBSD
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D17805
A crash was reported where the crash occurred in nfs_advlock() when the
NFS_ISV4(vp) macro was being executed. This was caused by the vnode
being VI_DOOMED due to a forced dismount in progress.
This patch fixes the problem by locking the vnode before executing the
NFS_ISV4() macro.
Tested by: rlibby
PR: 232673
Reviewed by: kib
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D17757
Use bypass to catch any NFS VOP dispatch and route it through the
wrapper which does sigdeferstop() and then dispatches original
VOP. NFS does not need a bypass below it, which is not supported.
The vop offset in the vop_vector is added since otherwise it is
impossible to get vop_op_t from the internal table, and I did not
wanted to create the layered fs only to wrap NFS VOPs.
VFS_OP()s wrap is straightforward.
Requested and reviewed by: mjg (previous version)
Tested by: pho
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D17658
Newer versions of gcc generate "might not be initialized" warnings for
several variables in nfsrpc_doiods(). I have checked and all of these
variables are assigned values before they are used.
In the one case of "tdrpc", it could have passed garbage as an argument
to nfscl_dofflayoutio() when mirrorcnt is one. However nfscl_dofflayoutio() only
uses the argument when mirrorcnt > 1, so it wasn't actually broken.
This patch initializes "tdrpc" to avoid confusion and initializes the rest
to make the compiler happy.
Requested by: mmacy
Newer versions of gcc generate "set, but not used" warnings.
Add __unused macros to silence these warnings.
Although the variables are not being used, they are values parsed from
arguments to callback RPCs that might be needed in the future.
Requested by: mmacy
When a NFSv4.1 client mount using pNFS detects a failure trying to do a
Renew (actually just a Sequence operation), the code would simply try
again and again and again every 30sec.
This would tie up the "nfscl" thread, which should also be doing other
things like Renews on other DSs and the MDS.
This patch adds code which closes down the TCP connection and marks it
defunct when Renew detects an failure to communicate with the DS, so
further Renews will not be attempted until a new working TCP connection to
the DS is established.
It also makes the call to nfscl_cancelreqs() unconditional, since
nfscl_cancelreqs() checks the NFSCLDS_SAMECONN flag and does so while holding
the lock.
This fix only applies to the NFSv4.1 client whne using pNFS and without it
the only effect would have been an "nfscl" thread busy doing Renew attempts
on an unresponsive DS.
MFC after: 2 weeks
Without this patch, the client side NFSv4.1 pNFS code erroneously did writes
and commits to both DS mirrors using the TCP connection of the first one.
For my test setup this worked, since I have both DSs running on the same
machine, but it would have failed when the DSs are on separate machines.
This patch fixes the code to use the correct TCP connection for each DS.
This patch should only affect the NFSv4.1 client when using "pnfs" mounts
to mirrored DSs.
MFC after: 2 weeks
So long as the TCP connection to a pNFS DS isn't shared with other DSs,
it can be closed down when the DS is being disabled in the pNFS client.
This causes any RPCs in progress to fail.
This patch only affects the NFSv4.1 pNFS client when errors occur
while doing I/O on a DS.
MFC after: 2 weeks
an I/O attempt on a DS to the server via LayoutReturn.
The current FreeBSD client can generate these errors for an operational
DS while doing a recovery of a mirror after a mirrored DS has been repaired.
I am not sure why these errors occur, but my best current guess is a race
between the Layout Recall issued by the kernel code run from pnfsdscopymr(8)
and a Read operation on the DS for the file bing copied.
The errrors are not fatal, since the client falls back on doing I/O through
the MDS, which can do the I/O successfully as a proxy. (The fact that the
MDS can do this indicates that the file does still exist on the functioning
DS.)
This patch only affects behaviour of the pNFS client and only when using
Flexible File layouts.
MFC after: 2 weeks
Without this patch, the NFSv4.1 pNFS client shared a single TCP connection
for all DSs that resided on the same machine. This made disabling one of
the DSs impossible. Although unlikely, it is possible that the storage
subsystem has failed in such a way that the storage for one DS on a machine
is no longer functioning correctly, but the storage used by another DS on
the same machine is still ok. For this case, it would be nice if a system
can fail one of the DSs without failing them all.
This patch changes the default behaviour to use separate TCP connections
for each DS even if they reside on the same machine.
I do not believe that this will be a problem for extant pNFS servers, but
a sysctl can be set to restore the old behaviour if this change causes a
problem for an extant pNFS server.
This patch only affects the NFSv4.1 pNFS client.
MFC after: 2 weeks
When the NFSv4.1 pNFS client gets an error for a DS I/O operation using a
Flexible File layout, it returns the layout with an error.
This patch changes the code slightly, so that it returns the layout for all
errors except EACCES and lets the MDS decide what to do based on the error.
It also makes a couple of changes to nfscl_layoutrecall() to ensure that
the first layoutreturn(s) will have the error in the reply.
Plus, the patch adds a wakeup() so that the "nfscl" thread won't wait 1sec
before doing the LayoutReturn.
Tested against the pNFS service.
This patch should not affect non-pNFS use of the client.
The unused "dsp" argument will be used by a future patch that disables the
connection to the DS when possible.
MFC after: 2 weeks
The Flexible File layout LayoutReturn operation has argument fields where
an I/O error encountered when attempting I/O on a DS can be reported back
to the MDS.
This patch adds code to the client to do this for the Flexible File layout
mirrored case.
This patch should only affect mounts using the "pnfs" option against servers
that support the Flexible File layout.
MFC after: 2 weeks
Four functions nfscl_reqstart(), nfscl_fillsattr(), nfsm_stateidtom()
and nfsmnt_mdssession() are now called from within the nfsd.
As such, they needed to be moved from nfscl.ko to nfscommon.ko so that
nfsd.ko would load when nfscl.ko wasn't loaded.
Reported by: herbert@gojira.at
the old encodings for the lower 16 and 32 bits and only using the
higher 32 bits for unusually large major and minor numbers. This
change breaks compatibility with the previous encoding (which was only
used in -current).
Fix truncation to (essentially) 16-bit dev_t in newnfs v3.
Any encoding of device numbers gives an ABI, so it can't be changed
without translations for compatibility. Extra bits give the much
larger complication that the translations need to compress into fewer
bits. Fortunately, more than 32 bits are rarely needed, so
compression is rarely needed except for 16-bit linux dev_t where it
was always needed but never done.
The previous encoding moved the major number into the top 32 bits.
Almost no translation code handled this, so the major number was blindly
truncated away in most 32-bit encodings. E.g., for ffs, mknod(8) with
major = 1 and minor = 2 gave dev_t = 0x10000002; ffs cannot represent
this and blindly truncated it to 2. But if this mknod was run on any
released version of FreeBSD, it gives dev_t = 0x102. ffs can represent
this, but in the previous encoding it was not decoded, giving major = 0,
minor = 0x102.
The presence of bugs was most obvious for exporting dev_t's from an
old system to -current, since bugs in newnfs augment them. I fixed
oldnfs to support 32-bit dev_t in 1996 (r16634), but this regressed
to 16-bit dev_t in newnfs, first to the old 16-bit encoding and then
further in -current. E.g., old ad0 with major = 234, minor = 0x10002
had the correct (major, minor) number on the wire, but newnfs truncated
this to (234, 2) and then the previous encoding shifted the major
number into oblivion as seen by ffs or old applications.
I first tried to fix this by translating on every ABI/API boundary, but
there are too many boundaries and too many sloppy translations by blind
truncation. So use the old encoding for the low 32 bits so that sloppy
translations work no worse than before provided the high 32 bits are
not set. Add some error checking for when bits are lost. Keep not
doing any error checking for translations for almost everything in
compat/linux.
compat/freebsd32/freebsd32_misc.c:
Optionally check for losing bits after possibly-truncating assignments as
before.
compat/linux/linux_stats.c:
Depend on the representation being compatible with Linux's (or just with
itself for local use) and spell some of the translations as assignments in
a macro that hides the details.
fs/nfsclient/nfs_clcomsubs.c:
Essentially the same fix as in 1996, except there is now no possible
truncation in makedev() itself. Also fix nearby style bugs.
kern/vfs_syscalls.c:
As for freebsd32. Also update the sysctl description to include file
numbers, and change it to describe device ids as device numbers.
sys/types.h:
Use inline functions (wrapped by macros) since the expressions are now
a bit too complicated for plain macros. Describe the encoding and
some of the reasons for it. 16-bit compatibility didn't leave many
reasonable choices for the 32-bit encoding, and 32-bit compatibility
doesn't leave many reasonable choices for the 64-bit encoding. My
choice is to put the 8 new minor bits in the low 8 bits of the top 32
bits. This minimizes discontiguities.
Reviewed by: kib (except for rewrite of the comment in linux_stats.c)
This code merge adds a pNFS service to the NFSv4.1 server. Although it is
a large commit it should not affect behaviour for a non-pNFS NFS server.
Some documentation on how this works can be found at:
http://people.freebsd.org/~rmacklem/pnfs-planb-setup.txt
and will hopefully be turned into a proper document soon.
This is a merge of the kernel code. Userland and man page changes will
come soon, once the dust settles on this merge.
It has passed a "make universe", so I hope it will not cause build problems.
It also adds NFSv4.1 server support for the "current stateid".
Here is a brief overview of the pNFS service:
A pNFS service separates the Read/Write oeprations from all the other NFSv4.1
Metadata operations. It is hoped that this separation allows a pNFS service
to be configured that exceeds the limits of a single NFS server for either
storage capacity and/or I/O bandwidth.
It is possible to configure mirroring within the data servers (DSs) so that
the data storage file for an MDS file will be mirrored on two or more of
the DSs.
When this is used, failure of a DS will not stop the pNFS service and a
failed DS can be recovered once repaired while the pNFS service continues
to operate. Although two way mirroring would be the norm, it is possible
to set a mirroring level of up to four or the number of DSs, whichever is
less.
The Metadata server will always be a single point of failure,
just as a single NFS server is.
A Plan B pNFS service consists of a single MetaData Server (MDS) and K
Data Servers (DS), all of which are recent FreeBSD systems.
Clients will mount the MDS as they would a single NFS server.
When files are created, the MDS creates a file tree identical to what a
single NFS server creates, except that all the regular (VREG) files will
be empty. As such, if you look at the exported tree on the MDS directly
on the MDS server (not via an NFS mount), the files will all be of size 0.
Each of these files will also have two extended attributes in the system
attribute name space:
pnfsd.dsfile - This extended attrbute stores the information that
the MDS needs to find the data storage file(s) on DS(s) for this file.
pnfsd.dsattr - This extended attribute stores the Size, AccessTime, ModifyTime
and Change attributes for the file, so that the MDS doesn't need to
acquire the attributes from the DS for every Getattr operation.
For each regular (VREG) file, the MDS creates a data storage file on one
(or more if mirroring is enabled) of the DSs in one of the "dsNN"
subdirectories. The name of this file is the file handle
of the file on the MDS in hexadecimal so that the name is unique.
The DSs use subdirectories named "ds0" to "dsN" so that no one directory
gets too large. The value of "N" is set via the sysctl vfs.nfsd.dsdirsize
on the MDS, with the default being 20.
For production servers that will store a lot of files, this value should
probably be much larger.
It can be increased when the "nfsd" daemon is not running on the MDS,
once the "dsK" directories are created.
For pNFS aware NFSv4.1 clients, the FreeBSD server will return two pieces
of information to the client that allows it to do I/O directly to the DS.
DeviceInfo - This is relatively static information that defines what a DS
is. The critical bits of information returned by the FreeBSD
server is the IP address of the DS and, for the Flexible
File layout, that NFSv4.1 is to be used and that it is
"tightly coupled".
There is a "deviceid" which identifies the DeviceInfo.
Layout - This is per file and can be recalled by the server when it
is no longer valid. For the FreeBSD server, there is support
for two types of layout, call File and Flexible File layout.
Both allow the client to do I/O on the DS via NFSv4.1 I/O
operations. The Flexible File layout is a more recent variant
that allows specification of mirrors, where the client is
expected to do writes to all mirrors to maintain them in a
consistent state. The Flexible File layout also allows the
client to report I/O errors for a DS back to the MDS.
The Flexible File layout supports two variants referred to as
"tightly coupled" vs "loosely coupled". The FreeBSD server always
uses the "tightly coupled" variant where the client uses the
same credentials to do I/O on the DS as it would on the MDS.
For the "loosely coupled" variant, the layout specifies a
synthetic user/group that the client uses to do I/O on the DS.
The FreeBSD server does not do striping and always returns
layouts for the entire file. The critical information in a layout
is Read vs Read/Writea and DeviceID(s) that identify which
DS(s) the data is stored on.
At this time, the MDS generates File Layout layouts to NFSv4.1 clients
that know how to do pNFS for the non-mirrored DS case unless the sysctl
vfs.nfsd.default_flexfile is set non-zero, in which case Flexible File
layouts are generated.
The mirrored DS configuration always generates Flexible File layouts.
For NFS clients that do not support NFSv4.1 pNFS, all I/O operations
are done against the MDS which acts as a proxy for the appropriate DS(s).
When the MDS receives an I/O RPC, it will do the RPC on the DS as a proxy.
If the DS is on the same machine, the MDS/DS will do the RPC on the DS as
a proxy and so on, until the machine runs out of some resource, such as
session slots or mbufs.
As such, DSs must be separate systems from the MDS.
Tested by: james.rose@framestore.com
Relnotes: yes
There were a couple of cases in newnfs_request() that it assumed that it
was an NFSv4.1 mount with a session. This should always be the case when
a Sequence operation is in the reply or the server replies NFSERR_BADSESSION.
However, if a server was broken and sent an erroneous reply, these safety
belt checks should avoid trouble.
The one check required a small tweak to nfsmnt_mdssession() so that it
returns NULL when there is no session instead of the offset of the field
in the structure (0x8 for i386).
This patch should have no effect on normal operation of the client.
Found by inspection during pNFS server development.
MFC after: 2 weeks
The Flexible File layout case wasn't handled by LayoutRecall callbacks
because it just checked for File layout and returned NFSERR_NOMATCHLAYOUT
otherwise. This patch adds the Flexible File layout handling.
Found during testing of the pNFS server.
MFC after: 2 weeks
The intent was that the default would be based on number of CPUs, but the
code disabled using taskqueue() by default.
This code is only executed when mounting a NFSv4.1 server that supports the
Flexible File layout for pNFS and, since such servers are rare, this change
shouldn't result in a POLA violation.
(The FreeBSD pNFS server is still a project and the only other one that
uses Flexible File layout is being developed by Primary Data and I don't
know if they have even shipped any to customers yet.)
Found while testing the pNFS server.
The sleep for I/O completion during an NFSv4.1 pNFS layout recall used
the wrong event value and could result in the "[nfscl]" thread hung
for the mount.
This patch fixes the event to be the correct.
This bug will only affect NFSv4.1 pnfs mounts and only when the server
does a layout recall callback, so it won't affect many. Without the patch,
a mount without the "pnfs" option will avoid the problem.
Found during testing of the pNFS server.
MFC after: 1 week
Using a pointer after setting it NULL is probably not a good plan.
Spotted by inspection during changes for Flexible File Layout Ioerr handling.
This code path obviously isn't normally executed.
MFC after: 1 week
Mechanically replace uses of MALLOC/FREE with appropriate invocations of
malloc(9) / free(9) (a series of sed expressions). Something like:
* MALLOC(a, b, ... -> a = malloc(...
* FREE( -> free(
* free((caddr_t) -> free(
No functional change.
For now, punt on modifying contrib ipfilter code, leaving a definition of
the macro in its KMALLOC().
Reported by: jhb
Reviewed by: cy, imp, markj, rmacklem
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D14035
When allocating memory through malloc(9), we always expect the amount of
memory requested to be unsigned as a negative value would either stand for
an error or an overflow.
Unsign some values, found when considering the use of mallocarray(9), to
avoid unnecessary casting. Also consider that indexes should be of
at least the same size/type as the upper limit they pretend to index.
MFC after: 3 weeks
Uses of mallocarray(9).
The use of mallocarray(9) has rocketed the required swap to build FreeBSD.
This is likely caused by the allocation size attributes which put extra pressure
on the compiler.
Given that most of these checks are superfluous we have to choose better
where to use mallocarray(9). We still have more uses of mallocarray(9) but
hopefully this is enough to bring swap usage to a reasonable level.
Reported by: wosch
PR: 225197
Focus on code where we are doing multiplications within malloc(9). None of
these ire likely to overflow, however the change is still useful as some
static checkers can benefit from the allocation attributes we use for
mallocarray.
This initial sweep only covers malloc(9) calls with M_NOWAIT. No good
reason but I started doing the changes before r327796 and at that time it
was convenient to make sure the sorrounding code could handle NULL values.
X-Differential revision: https://reviews.freebsd.org/D13837
This reduces noise when kernel is compiled by newer GCC versions,
such as one used by external toolchain ports.
Reviewed by: kib, andrew(sys/arm and sys/arm64), emaste(partial), erj(partial)
Reviewed by: jhb (sys/dev/pci/* sys/kern/vfs_aio.c and sys/kern/kern_synch.c)
Differential Revision: https://reviews.freebsd.org/D10385
gcc complaints that the comparision is always false due to the value
range, and the cast does not prevent the analysis. Split the LP64
vs. ILP32 clamping as a workaround.
Sponsored by: The FreeBSD Foundation
On the one hand, FIFOs should respect other variables not supported by
the fifofs vnode operation (such as _PC_NAME_MAX, _PC_LINK_MAX, etc.).
These values are fs-specific and must come from a fs-specific method.
On the other hand, filesystems that support FIFOs are required to
support _PC_PIPE_BUF on directory vnodes that can contain FIFOs.
Given this latter requirement, once the fs-specific VOP_PATHCONF
method supports _PC_PIPE_BUF for directories, it is also suitable for
FIFOs permitting a single VOP_PATHCONF method to be used for both
FIFOs and non-FIFOs.
To that end, retire all of the FIFO-specific pathconf methods from
filesystems and change FIFO-specific vnode operation switches to use
the existing fs-specific VOP_PATHCONF method. For fifofs, set it's
VOP_PATHCONF to VOP_PANIC since it should no longer be used.
While here, move _PC_PIPE_BUF handling out of vop_stdpathconf() so that
only filesystems supporting FIFOs will report a value. In addition,
only report a valid _PC_PIPE_BUF for directories and FIFOs.
Discussed with: bde
Reviewed by: kib (part of a larger patch)
MFC after: 1 month
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D12572
- Define a NFS_LINK_MAX as UINT32_MAX to match the wire protocol.
- Use NFS_LINK_MAX instead of LINK_MAX as the fallback value reported
for a PATHCONF RPC by the NFS server.
- Use NFS_LINK_MAX instead of LINK_MAX as the default value reported
by the NFS client pathconf() if not overridden by the NFS server.
- When reading the link count out of an RPC reply, read the full 32
bits instead of the lower 16 bits.
Reviewed by: rmacklem (earlier version)
Sponsored by: Chelsio Communications
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
Mainly focus on files that use BSD 3-Clause license.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.
When the NFSv4.1 pNFS client is using a Flexible File Layout specifying
mirrored Data Servers, it must do the writes and commits to all mirrors.
This patch modifies the client to use a taskqueue to perform these writes
and commits concurrently.
The number of threads can't be changed for taskqueue(9), so it is set
to 4 * mp_ncpus by default, but this can be overridden by setting the
sysctl vfs.nfs.pnfsiothreads.
Differential Revision: https://reviews.freebsd.org/D12632
This patch adds support for the Flexible File Layout to the pNFS client.
Although the patch is rather large, it should only affect NFS mounts
using the "pnfs" option against pNFS servers that do not support File
Layout.
There are still a couple of things missing from the Flexible File Layout
client implementation:
- The code does not yet do a LayoutReturn with I/O error stats when
I/O error(s) occur when attempting to do I/O on a DS.
This will be fixed in a future commit, since it is important for the
MDS to know that I/O on a DS is failing.
- The current code does writes and commits to mirror DSs serially.
Making them happen concurrently will be done in a future commit,
after discussion on freebsd-current@ on the best way to do this.
- The code does not handle NFSv4.0 DSs. Since there is no extant pNFS
server that implements NFSv4.0 DSs and NFSv4.1 DSs makes more sense
now, I don't intend to implement this until there is a need for it.
There is support for NFSv4.1 and NFSv3 DSs.
This patch changes nfsv4_getipaddr() and nfsrpc_fillsa() to use
a sockaddr_in * and sockaddr_in6 * instead of sockaddr_storage, to
avoid allocating the latter on the stack. It also moves the nfsrpc_fillsa()
call to after the completion of parsing of the DeviceInfo reply from
the server. This patch is in preparation for addition of Flex File
Layout support in a future commit.
It only affects the "pnfs" NFSv4.1 client mount option and should not
have changed its semantics.
When a "pnfs" NFSv4.1 mount was unmounted, it didn't free up the layouts
and deviceinfo structures. This leak only affects "pnfs" mounts and only
when the mount is umounted.
Found while testing the pNFS Flexible File layout client code.
MFC after: 2 weeks
This patch adds "vers" and "minorvers" arguments to nfscl_reqstart().
The patch always passes them in as "0" and that implies no change
in semantics. These arguments will be used by a future commit that
adds support for the Flexible File Layout.
nfsm_uiombuflist() zero filled the mbuf list to a multiple of 4bytes
as required for XDR. Unfortunately that modified an mbuf list after
it was m_copym()'d and was broken. This patch removes the zero filling code.
Since nfsm_uiombuflist() is not yet used in head/current, this has no
effect on users.
The function will be used by a future commit of code that adds Flex
File Layout support.
Make the NFSv4 pNFS client function nfsrpc_layoutget() a static, since it
is only used in sys/fs/nfsclient/nfs_clrpcops.c.
This prepares the code for future patches that add Flex File layout
support.
This patch adds a new function called nfsm_uiombuflist(), which is
similar to nfsm_uiombuf(), but doesn't not use the fields in
struct nfsrv_descript. This new function will be used by the pNFS client
for writing to mirrors using Flex Files layout.
The function is not yet called anywhere.
Also, get rid of #ifndef APPLE, which is ancient cruft left over from
the Mac OSX port of the NFSv4 client.
Simplify nfsrpc_layoutreturn() args. in preparation for the addition
of Flex File layout support, since File layout uses a 0 length field.
Flex Files does use a longer field, but that will be added in a
subsequent commit.
The code in nfscl_doflayoutio() bogusly used FREAD instead of
NFSV4OPEN_ACCESSREAD. Since both happen to be defined as "1", this
worked and the patch doesn't result in a functional change.
Found by inspection during development of Flex File Layout support.
MFC after: 2 weeks
