xprt_lookup_rqst() and bc_send_request() display a byte-swapped XID,
but receive_cb_reply() does not.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
We really do not want to do ioctls in the server's fast path. Instead, let's
use the fact that we managed to read a full record as the indicator that
we should try to read the socket again.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
If requests are queued in the socket inbuffer waiting for an
svc_tcp_has_wspace() requirement to be satisfied, then we do not want
to clear the SOCK_NOSPACE flag until we've satisfied that requirement.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
The current code always selects XPRT_TRANSPORT_BC_TCP for the back
channel, even when the forward channel was not TCP (eg, RDMA). When
a 4.1 mount is attempted with RDMA, the server panics in the TCP BC
code when trying to send CB_NULL.
Instead, construct the transport protocol number from the forward
channel transport or'd with XPRT_TRANSPORT_BC. Transports that do
not support bi-directional RPC will not have registered a "BC"
transport, causing create_backchannel_client() to fail immediately.
Fixes: https://bugzilla.linux-nfs.org/show_bug.cgi?id=265
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
When debugging, rpc prints messages from dprintk(KERN_WARNING ...)
with "^A4" prefixed,
[ 2780.339988] ^A4nfsd: connect from unprivileged port: 127.0.0.1, port=35316
Trond tells,
> dprintk != printk. We have NEVER supported dprintk(KERN_WARNING...)
This patch removes using of dprintk with KERN_WARNING.
Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
If an incoming NFS request is coming from the local host, then
nfsd will need to perform some special handling. So detect that
possibility and make the source visible in rq_local.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
An NFS/RDMA client's source port is meaningless for RDMA transports.
The transport layer typically sets the source port value on the
connection to a random ephemeral port.
Currently, NFS server administrators must specify the "insecure"
export option to enable clients to access exports via RDMA.
But this means NFS clients can access such an export via IP using an
ephemeral port, which may not be desirable.
This patch eliminates the need to specify the "insecure" export
option to allow NFS/RDMA clients access to an export.
BugLink: https://bugzilla.linux-nfs.org/show_bug.cgi?id=250
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Pull yet more networking updates from David Miller:
1) Various fixes to the new Redpine Signals wireless driver, from
Fariya Fatima.
2) L2TP PPP connect code takes PMTU from the wrong socket, fix from
Dmitry Petukhov.
3) UFO and TSO packets differ in whether they include the protocol
header in gso_size, account for that in skb_gso_transport_seglen().
From Florian Westphal.
4) If VLAN untagging fails, we double free the SKB in the bridging
output path. From Toshiaki Makita.
5) Several call sites of sk->sk_data_ready() were referencing an SKB
just added to the socket receive queue in order to calculate the
second argument via skb->len. This is dangerous because the moment
the skb is added to the receive queue it can be consumed in another
context and freed up.
It turns out also that none of the sk->sk_data_ready()
implementations even care about this second argument.
So just kill it off and thus fix all these use-after-free bugs as a
side effect.
6) Fix inverted test in tcp_v6_send_response(), from Lorenzo Colitti.
7) pktgen needs to do locking properly for LLTX devices, from Daniel
Borkmann.
8) xen-netfront driver initializes TX array entries in RX loop :-) From
Vincenzo Maffione.
9) After refactoring, some tunnel drivers allow a tunnel to be
configured on top itself. Fix from Nicolas Dichtel.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (46 commits)
vti: don't allow to add the same tunnel twice
gre: don't allow to add the same tunnel twice
drivers: net: xen-netfront: fix array initialization bug
pktgen: be friendly to LLTX devices
r8152: check RTL8152_UNPLUG
net: sun4i-emac: add promiscuous support
net/apne: replace IS_ERR and PTR_ERR with PTR_ERR_OR_ZERO
net: ipv6: Fix oif in TCP SYN+ACK route lookup.
drivers: net: cpsw: enable interrupts after napi enable and clearing previous interrupts
drivers: net: cpsw: discard all packets received when interface is down
net: Fix use after free by removing length arg from sk_data_ready callbacks.
Drivers: net: hyperv: Address UDP checksum issues
Drivers: net: hyperv: Negotiate suitable ndis version for offload support
Drivers: net: hyperv: Allocate memory for all possible per-pecket information
bridge: Fix double free and memory leak around br_allowed_ingress
bonding: Remove debug_fs files when module init fails
i40evf: program RSS LUT correctly
i40evf: remove open-coded skb_cow_head
ixgb: remove open-coded skb_cow_head
igbvf: remove open-coded skb_cow_head
...
Several spots in the kernel perform a sequence like:
skb_queue_tail(&sk->s_receive_queue, skb);
sk->sk_data_ready(sk, skb->len);
But at the moment we place the SKB onto the socket receive queue it
can be consumed and freed up. So this skb->len access is potentially
to freed up memory.
Furthermore, the skb->len can be modified by the consumer so it is
possible that the value isn't accurate.
And finally, no actual implementation of this callback actually uses
the length argument. And since nobody actually cared about it's
value, lots of call sites pass arbitrary values in such as '0' and
even '1'.
So just remove the length argument from the callback, that way there
is no confusion whatsoever and all of these use-after-free cases get
fixed as a side effect.
Based upon a patch by Eric Dumazet and his suggestion to audit this
issue tree-wide.
Signed-off-by: David S. Miller <davem@davemloft.net>
There could be a case, when NFSd file system is mounted in network, different
to socket's one, like below:
"ip netns exec" creates new network and mount namespace, which duplicates NFSd
mount point, created in init_net context. And thus NFS server stop in nested
network context leads to RPCBIND client destruction in init_net.
Then, on NFSd start in nested network context, rpc.nfsd process creates socket
in nested net and passes it into "write_ports", which leads to RPCBIND sockets
creation in init_net context because of the same reason (NFSd monut point was
created in init_net context). An attempt to register passed socket in nested
net leads to panic, because no RPCBIND client present in nexted network
namespace.
This patch add check that passed socket's net matches NFSd superblock's one.
And returns -EINVAL error to user psace otherwise.
v2: Put socket on exit.
Reported-by: Weng Meiling <wengmeiling.weng@huawei.com>
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
CONFIG_IPV6=n is still a valid choice ;)
It appears we can remove dead code.
Reported-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
TCP listener refactoring, part 4 :
To speed up inet lookups, we moved IPv4 addresses from inet to struct
sock_common
Now is time to do the same for IPv6, because it permits us to have fast
lookups for all kind of sockets, including upcoming SYN_RECV.
Getting IPv6 addresses in TCP lookups currently requires two extra cache
lines, plus a dereference (and memory stall).
inet6_sk(sk) does the dereference of inet_sk(__sk)->pinet6
This patch is way bigger than its IPv4 counter part, because for IPv4,
we could add aliases (inet_daddr, inet_rcv_saddr), while on IPv6,
it's not doable easily.
inet6_sk(sk)->daddr becomes sk->sk_v6_daddr
inet6_sk(sk)->rcv_saddr becomes sk->sk_v6_rcv_saddr
And timewait socket also have tw->tw_v6_daddr & tw->tw_v6_rcv_saddr
at the same offset.
We get rid of INET6_TW_MATCH() as INET6_MATCH() is now the generic
macro.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Since we enabled auto-tuning for sunrpc TCP connections we do not
guarantee that there is enough write-space on each connection to
queue a reply.
If memory pressure causes the window to shrink too small, the request
throttling in sunrpc/svc will not accept any requests so no more requests
will be handled. Even when pressure decreases the window will not
grow again until data is sent on the connection.
This means we get a deadlock: no requests will be handled until there
is more space, and no space will be allocated until a request is
handled.
This can be simulated by modifying svc_tcp_has_wspace to inflate the
number of byte required and removing the 'svc_sock_setbufsize' calls
in svc_setup_socket.
I found that multiplying by 16 was enough to make the requirement
exceed the default allocation. With this modification in place:
mount -o vers=3,proto=tcp 127.0.0.1:/home /mnt
would block and eventually time out because the nfs server could not
accept any requests.
This patch relaxes the request throttling to always allow at least one
request through per connection. It does this by checking both
sk_stream_min_wspace() and xprt->xpt_reserved
are zero.
The first is zero when the TCP transmit queue is empty.
The second is zero when there are no RPC requests being processed.
When both of these are zero the socket is idle and so one more
request can safely be allowed through.
Applying this patch allows the above mount command to succeed cleanly.
Tracing shows that the allocated write buffer space quickly grows and
after a few requests are handled, the extra tests are no longer needed
to permit further requests to be processed.
The main purpose of request throttling is to handle the case when one
client is slow at collecting replies and the send queue gets full of
replies that the client hasn't acknowledged (at the TCP level) yet.
As we only change behaviour when the send queue is empty this main
purpose is still preserved.
Reported-by: Ben Myers <bpm@sgi.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Several call sites use the hardcoded following condition :
sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)
Lets use a helper because TCP_NOTSENT_LOWAT support will change this
condition for TCP sockets.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Though clients we care about mostly don't do this, it is possible for
rpc requests to be sent in multiple fragments. Here we have a sanity
check to ensure that the final received rpc isn't too small--except that
the number we're actually checking is the length of just the final
fragment, not of the whole rpc. So a perfectly legal rpc that's
unluckily fragmented could cause the server to close the connection
here.
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
If we detect that an rpc is too short, we abort and close the
connection. Except, there's a bug here: we're leaving sk_datalen
nonzero without leaving any pages in the sk_pages array. The most
likely result of the inconsistency is a subsequent crash in
svc_tcp_clear_pages.
Also demote the BUG_ON in svc_tcp_clear_pages to a WARN.
Cc: stable@kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
The datagram_*_ctl functions in net/ipv6/datagram.c are IPv6-specific. Since
datagram_send_ctl is publicly exported it should be appropriately named to
reflect the fact that it's for IPv6 only.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull nfsd update from Bruce Fields:
"Included this time:
- more nfsd containerization work from Stanislav Kinsbursky: we're
not quite there yet, but should be by 3.9.
- NFSv4.1 progress: implementation of basic backchannel security
negotiation and the mandatory BACKCHANNEL_CTL operation. See
http://wiki.linux-nfs.org/wiki/index.php/Server_4.0_and_4.1_issues
for remaining TODO's
- Fixes for some bugs that could be triggered by unusual compounds.
Our xdr code wasn't designed with v4 compounds in mind, and it
shows. A more thorough rewrite is still a todo.
- If you've ever seen "RPC: multiple fragments per record not
supported" logged while using some sort of odd userland NFS client,
that should now be fixed.
- Further work from Jeff Layton on our mechanism for storing
information about NFSv4 clients across reboots.
- Further work from Bryan Schumaker on his fault-injection mechanism
(which allows us to discard selective NFSv4 state, to excercise
rarely-taken recovery code paths in the client.)
- The usual mix of miscellaneous bugs and cleanup.
Thanks to everyone who tested or contributed this cycle."
* 'for-3.8' of git://linux-nfs.org/~bfields/linux: (111 commits)
nfsd4: don't leave freed stateid hashed
nfsd4: free_stateid can use the current stateid
nfsd4: cleanup: replace rq_resused count by rq_next_page pointer
nfsd: warn on odd reply state in nfsd_vfs_read
nfsd4: fix oops on unusual readlike compound
nfsd4: disable zero-copy on non-final read ops
svcrpc: fix some printks
NFSD: Correct the size calculation in fault_inject_write
NFSD: Pass correct buffer size to rpc_ntop
nfsd: pass proper net to nfsd_destroy() from NFSd kthreads
nfsd: simplify service shutdown
nfsd: replace boolean nfsd_up flag by users counter
nfsd: simplify NFSv4 state init and shutdown
nfsd: introduce helpers for generic resources init and shutdown
nfsd: make NFSd service structure allocated per net
nfsd: make NFSd service boot time per-net
nfsd: per-net NFSd up flag introduced
nfsd: move per-net startup code to separated function
nfsd: pass net to __write_ports() and down
nfsd: pass net to nfsd_set_nrthreads()
...
Over TCP, RPC's are preceded by a single 4-byte field telling you how
long the rpc is (in bytes). The spec also allows you to send an RPC in
multiple such records (the high bit of the length field is used to tell
you whether this is the final record).
We've survived for years without supporting this because in practice the
clients we care about don't use it. But the userland rpc libraries do,
and every now and then an experimental client will run into this. (Most
recently I noticed it while trying to write a pynfs check.) And we're
really on the wrong side of the spec here--let's fix this.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Keep a separate field, sk_datalen, that tracks only the data contained
in a fragment, not including the fragment header.
For now, this is always just max(0, sk_tcplen - 4), but after we allow
multiple fragments sk_datalen will accumulate the total rpc data size
while sk_tcplen only tracks progress receiving the current fragment.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
The full reclen doesn't include the fragment header, but sk_tcplen does.
Fix this to make it an apples-to-apples comparison.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Soon we want to support multiple fragments, in which case it may be
legal for a single fragment to be smaller than 8 bytes, so we'll want to
delay this check till we've reached the last fragment.
Also fix an outdated comment.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Byte-swapping in place is always a little dubious.
Let's instead define this field to always be big-endian, and do the
swapping on demand where we need it.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Replace multiple BUG_ON() calls with WARN_ON_ONCE() and early return when
sanity checking socket ownership (lock). The bind call will fail if the
socket was unsuccessfully reclassified.
Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
You can use nfsd/portlist to give nfsd additional sockets to listen on.
In theory you can also remove listening sockets this way. But nobody's
ever done that as far as I can tell.
Also this was partially broken in 2.6.25, by
a217813f90 "knfsd: Support adding
transports by writing portlist file".
(Note that we decide whether to take the "delfd" case by checking for a
digit--but what's actually expected in that case is something made by
svc_one_sock_name(), which won't begin with a digit.)
So, let's just rip out this stuff.
Acked-by: NeilBrown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
The only errors returned from xpo_recvfrom have been -EAGAIN and
-EAFNOSUPPORT. The latter was removed by a previous patch. That leaves
only -EAGAIN, which is treated just like 0 by the caller (svc_recv).
So, just ditch -EAGAIN and return 0 instead.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
None of the callers should see an unsupported address family (only one
of them even bothers to check for that case), so just check for the
buggy case in svc_addr_len and don't bother elsewhere.
Acked-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Mainly, use the kernel standard
err = -ERROR;
if (something_bad)
goto out;
normal case;
rather than
if (something_bad)
err = -ERROR
else {
normal case;
}
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Examination of svc_tcp_clear_pages shows that it assumes sk_tcplen is
consistent with sk_pages[] (in particular, sk_pages[n] can't be NULL if
sk_tcplen would lead us to expect n pages of data).
svc_tcp_restore_pages zeroes out sk_pages[] while leaving sk_tcplen.
This is OK, since both functions are serialized by XPT_BUSY. However,
that means the inconsistency must be repaired before dropping XPT_BUSY.
Therefore we should be ensuring that svc_tcp_save_pages repairs the
problem before exiting svc_tcp_recv_record on error.
Symptoms were a BUG() in svc_tcp_clear_pages.
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
dropwatch wrongly diagnose all received UDP packets as drops.
This patch removes trace_kfree_skb() done in skb_free_datagram_locked().
Locations calling skb_free_datagram_locked() should do it on their own.
As a result, drops are accounted on the right function.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Standardize the net core ratelimited logging functions.
Coalesce formats, align arguments.
Change a printk then vprintk sequence to use printf extension %pV.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Name them in a "backward compatible" manner, i.e. reuse or not
are still 1 and 0 respectively. The reuse value of 2 means that
the socket with it will forcibly reuse everyone else's port.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/sunrpc/svcsock.c:412:22: warning: incorrect type in assignment
(different address spaces)
- svc_partial_recvfrom now takes a struct kvec, so the variable
save_iovbase needs to be an ordinary (void *)
Make a bunch of variables in net/sunrpc/xprtsock.c static
Fix a couple of "warning: symbol 'foo' was not declared. Should it be
static?" reports.
Fix a couple of conflicting function declarations.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This is a cleanup patch.
Service temporary sockets can be TCP or RDMA only. But XPT_CHNGBUF service
socket flag is checked only for UDP sockets on receive.
Thus (if I don't miss something non-obvious) this bit raising for temporary
sockets can be removed.
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Fixes this build error when CONFIG_NET_NS is not set:
net/sunrpc/svcsock.c: In function 'svc_setup_socket':
net/sunrpc/svcsock.c:1412:40: error: 'struct sock_common' has no member named 'skc_net'
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Lockd and NFSd services will handle requests from and to many network
nsamespaces. And thus have to be registered and unregistered per network
namespace.
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
* 'for-3.3' of git://linux-nfs.org/~bfields/linux: (31 commits)
nfsd4: nfsd4_create_clid_dir return value is unused
NFSD: Change name of extended attribute containing junction
svcrpc: don't revert to SVC_POOL_DEFAULT on nfsd shutdown
svcrpc: fix double-free on shutdown of nfsd after changing pool mode
nfsd4: be forgiving in the absence of the recovery directory
nfsd4: fix spurious 4.1 post-reboot failures
NFSD: forget_delegations should use list_for_each_entry_safe
NFSD: Only reinitilize the recall_lru list under the recall lock
nfsd4: initialize special stateid's at compile time
NFSd: use network-namespace-aware cache registering routines
SUNRPC: create svc_xprt in proper network namespace
svcrpc: update outdated BKL comment
nfsd41: allow non-reclaim open-by-fh's in 4.1
svcrpc: avoid memory-corruption on pool shutdown
svcrpc: destroy server sockets all at once
svcrpc: make svc_delete_xprt static
nfsd: Fix oops when parsing a 0 length export
nfsd4: Use kmemdup rather than duplicating its implementation
nfsd4: add a separate (lockowner, inode) lookup
nfsd4: fix CONFIG_NFSD_FAULT_INJECTION compile error
...
This patch makes svc_xprt inherit network namespace link from its socket.
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
C assignment can handle struct in6_addr copying.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
With calls to modular infrastructure, these files really
needs the full module.h header. Call it out so some of the
cleanups of implicit and unrequired includes elsewhere can be
cleaned up.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
For IPv6 local address, lockd can not callback to client for
missing scope id when binding address at inet6_bind:
324 if (addr_type & IPV6_ADDR_LINKLOCAL) {
325 if (addr_len >= sizeof(struct sockaddr_in6) &&
326 addr->sin6_scope_id) {
327 /* Override any existing binding, if another one
328 * is supplied by user.
329 */
330 sk->sk_bound_dev_if = addr->sin6_scope_id;
331 }
332
333 /* Binding to link-local address requires an interface */
334 if (!sk->sk_bound_dev_if) {
335 err = -EINVAL;
336 goto out_unlock;
337 }
Replacing svc_addr_u by sockaddr_storage, let rqstp->rq_daddr contains more info
besides address.
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Mi Jinlong <mijinlong@cn.fujitsu.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
* 'nfs-for-3.1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (44 commits)
NFSv4: Don't use the delegation->inode in nfs_mark_return_delegation()
nfs: don't use d_move in nfs_async_rename_done
RDMA: Increasing RPCRDMA_MAX_DATA_SEGS
SUNRPC: Replace xprt->resend and xprt->sending with a priority queue
SUNRPC: Allow caller of rpc_sleep_on() to select priority levels
SUNRPC: Support dynamic slot allocation for TCP connections
SUNRPC: Clean up the slot table allocation
SUNRPC: Initalise the struct xprt upon allocation
SUNRPC: Ensure that we grab the XPRT_LOCK before calling xprt_alloc_slot
pnfs: simplify pnfs files module autoloading
nfs: document nfsv4 sillyrename issues
NFS: Convert nfs4_set_ds_client to EXPORT_SYMBOL_GPL
SUNRPC: Convert the backchannel exports to EXPORT_SYMBOL_GPL
SUNRPC: sunrpc should not explicitly depend on NFS config options
NFS: Clean up - simplify the switch to read/write-through-MDS
NFS: Move the pnfs write code into pnfs.c
NFS: Move the pnfs read code into pnfs.c
NFS: Allow the nfs_pageio_descriptor to signal that a re-coalesce is needed
NFS: Use the nfs_pageio_descriptor->pg_bsize in the read/write request
NFS: Cache rpc_ops in struct nfs_pageio_descriptor
...
