1
0
Fork 0
Commit Graph

38 Commits (7a05293af39fc716d0f51c0164cbb727302396a2)

Author SHA1 Message Date
Linus Torvalds 24717cfbbb The one new feature this time, from Anna Schumaker, is READ_PLUS, which
has the same arguments as READ but allows the server to return an array
 of data and hole extents.
 
 Otherwise it's a lot of cleanup and bugfixes.
 -----BEGIN PGP SIGNATURE-----
 
 iQJJBAABCAAzFiEEYtFWavXG9hZotryuJ5vNeUKO4b4FAl+Q5vsVHGJmaWVsZHNA
 ZmllbGRzZXMub3JnAAoJECebzXlCjuG+DUAP/RlALnXbaoWi8YCcEcc9U1LoQKbD
 CJpDR+FqCOyGwRuzWung/5pvkOO50fGEeAroos+2rF/NgRkQq8EFr9AuBhNOYUFE
 IZhWEOfu/r2ukXyBmcu21HGcWLwPnyJehvjuzTQW2wOHlBi/sdoL5Ap1sVlwVLj5
 EZ5kqJLD+ioG2sufW99Spi55l1Cy+3Y0IhLSWl4ZAE6s8hmFSYAJZFsOeI0Afx57
 USPTDRaeqjyEULkb+f8IhD0eRApOUo4evDn9dwQx+of7HPa1CiygctTKYwA3hnlc
 gXp2KpVA1REaiYVgOPwYlnqBmJ2K9X0wCRzcWy2razqEcVAX/2j7QCe9M2mn4DC8
 xZ2q4SxgXu9yf0qfUSVnDxWmP6ipqq7OmsG0JXTFseGKBdpjJY1qHhyqanVAGvEg
 I+xHnnWfGwNCftwyA3mt3RfSFPsbLlSBIMZxvN4kn8aVlqszGITOQvTdQcLYA6kT
 xWllBf4XKVXMqF0PzerxPDmfzBfhx6b1VPWOIVcu7VLBg3IXoEB2G5xG8MUJiSch
 OUTCt41LUQkerQlnzaZYqwmFdSBfXJefmcE/x/vps4VtQ/fPHX1jQyD7iTu3HfSP
 bRlkKHvNVeTodlBDe/HTPiTA99MShhBJyvtV5wfzIqwjc1cNreed+ePppxn8mxJi
 SmQ2uZk/MpUl7/V0
 =rcOj
 -----END PGP SIGNATURE-----

Merge tag 'nfsd-5.10' of git://linux-nfs.org/~bfields/linux

Pull nfsd updates from Bruce Fields:
 "The one new feature this time, from Anna Schumaker, is READ_PLUS,
  which has the same arguments as READ but allows the server to return
  an array of data and hole extents.

  Otherwise it's a lot of cleanup and bugfixes"

* tag 'nfsd-5.10' of git://linux-nfs.org/~bfields/linux: (43 commits)
  NFSv4.2: Fix NFS4ERR_STALE error when doing inter server copy
  SUNRPC: fix copying of multiple pages in gss_read_proxy_verf()
  sunrpc: raise kernel RPC channel buffer size
  svcrdma: fix bounce buffers for unaligned offsets and multiple pages
  nfsd: remove unneeded break
  net/sunrpc: Fix return value for sysctl sunrpc.transports
  NFSD: Encode a full READ_PLUS reply
  NFSD: Return both a hole and a data segment
  NFSD: Add READ_PLUS hole segment encoding
  NFSD: Add READ_PLUS data support
  NFSD: Hoist status code encoding into XDR encoder functions
  NFSD: Map nfserr_wrongsec outside of nfsd_dispatch
  NFSD: Remove the RETURN_STATUS() macro
  NFSD: Call NFSv2 encoders on error returns
  NFSD: Fix .pc_release method for NFSv2
  NFSD: Remove vestigial typedefs
  NFSD: Refactor nfsd_dispatch() error paths
  NFSD: Clean up nfsd_dispatch() variables
  NFSD: Clean up stale comments in nfsd_dispatch()
  NFSD: Clean up switch statement in nfsd_dispatch()
  ...
2020-10-22 09:44:27 -07:00
Randy Dunlap 1cc5213baa net: sunrpc: delete repeated words
Drop duplicate words in net/sunrpc/.
Also fix "Anyone" to be "Any one".

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: linux-nfs@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2020-09-25 18:01:26 -04:00
Alexander A. Klimov 0bdd4cea12 Replace HTTP links with HTTPS ones: NFS, SUNRPC, and LOCKD clients
Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.

Deterministic algorithm:
For each file:
  If not .svg:
    For each line:
      If doesn't contain `\bxmlns\b`:
        For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`:
          If both the HTTP and HTTPS versions
          return 200 OK and serve the same content:
            Replace HTTP with HTTPS.

Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2020-09-21 10:21:10 -04:00
Trond Myklebust 669996add4 SUNRPC: Destroy the back channel when we destroy the host transport
When we're destroying the host transport mechanism, we should ensure
that we do not leak memory by failing to release any back channel
slots that might still exist.

Reported-by: Neil Brown <neilb@suse.de>
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2019-10-30 12:04:35 -04:00
Trond Myklebust 875f0706ac SUNRPC: The TCP back channel mustn't disappear while requests are outstanding
If there are TCP back channel requests being processed by the
server threads, then we should hold a reference to the transport
to ensure it doesn't get freed from underneath us.

Reported-by: Neil Brown <neilb@suse.de>
Fixes: 2ea24497a1 ("SUNRPC: RPC callbacks may be split across several..")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2019-10-30 12:04:35 -04:00
Trond Myklebust 7402a4fedc SUNRPC: Fix up backchannel slot table accounting
Add a per-transport maximum limit in the socket case, and add
helpers to allow the NFSv4 code to discover that limit.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2019-07-18 01:12:59 -04:00
Trond Myklebust 0d1bf3407c SUNRPC: Allow dynamic allocation of back channel slots
Now that the reads happen in a process context rather than a softirq,
it is safe to allocate back channel slots using a reclaiming
allocation.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2019-03-02 16:25:26 -05:00
Trond Myklebust b9779a54bb SUNRPC: Ensure rq_bytes_sent is reset before request transmission
When we resend a request, ensure that the 'rq_bytes_sent' is reset
to zero.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2019-02-20 17:33:55 -05:00
Chuck Lever acf0a39f4f SUNRPC: Fix some kernel doc complaints
Clean up some warnings observed when building with "make W=1".

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2019-01-02 12:05:18 -05:00
Trond Myklebust edc81dcd5b SUNRPC: Refactor xprt_transmit() to remove the reply queue code
Separate out the action of adding a request to the reply queue so that the
backchannel code can simply skip calling it altogether.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2018-09-30 15:35:14 -04:00
Stephen Hemminger 8fdee4cc95 sunrpc: whitespace fixes
Remove trailing whitespace and blank line at EOF

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2018-07-31 12:53:40 -04:00
Trond Myklebust c89091c88d SUNRPC: Don't hold the transport lock when receiving backchannel data
The backchannel request has no associated task, so it is going nowhere
until we call xprt_complete_bc_request().

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2017-08-16 15:10:16 -04:00
Chuck Lever b9c5bc03be SUNRPC: Refactor rpc_xdr_buf_init()
Clean up: there is some XDR initialization logic that is common
to the forward channel and backchannel. Move it to an XDR header
so it can be shared.

rpc_rqst::rq_buffer points to a buffer containing big-endian data.
Update its annotation as part of the clean up.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2016-09-19 13:08:37 -04:00
Trond Myklebust 756b9b37cf SUNRPC: Fix callback channel
The NFSv4.1 callback channel is currently broken because the receive
message will keep shrinking because the backchannel receive buffer size
never gets reset.
The easiest solution to this problem is instead of changing the receive
buffer, to rather adjust the copied request.

Fixes: 38b7631fbe ("nfs4: limit callback decoding to received bytes")
Cc: Benjamin Coddington <bcodding@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-12-07 13:04:59 -08:00
Benjamin Coddington 38b7631fbe nfs4: limit callback decoding to received bytes
A truncated cb_compound request will cause the client to decode null or
data from a previous callback for nfs4.1 backchannel case, or uninitialized
data for the nfs4.0 case. This is because the path through
svc_process_common() advances the request's iov_base and decrements iov_len
without adjusting the overall xdr_buf's len field.  That causes
xdr_init_decode() to set up the xdr_stream with an incorrect length in
nfs4_callback_compound().

Fixing this for the nfs4.1 backchannel case first requires setting the
correct iov_len and page_len based on the length of received data in the
same manner as the nfs4.0 case.

Then the request's xdr_buf length can be adjusted for both cases based upon
the remaining iov_len and page_len.

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-11-23 22:03:15 -05:00
Chuck Lever 42e5c3e272 SUNRPC: Abstract backchannel operations
xprt_{setup,destroy}_backchannel() won't be adequate for RPC/RMDA
bi-direction. In particular, receive buffers have to be pre-
registered and posted in order to receive incoming backchannel
requests.

Add a virtual function call to allow the insertion of appropriate
backchannel setup and destruction methods for each transport.

In addition, freeing a backchannel request is a little different
for RPC/RDMA. Introduce an rpc_xprt_op to handle the difference.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Tested-By: Devesh Sharma <devesh.sharma@avagotech.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2015-11-02 13:45:15 -05:00
Trond Myklebust 1980bd4d82 SUNRPC: xprt_complete_bc_request must also decrement the free slot count
Calling xprt_complete_bc_request() effectively causes the slot to be allocated,
so it needs to decrement the backchannel free slot count as well.

Fixes: 0d2a970d0a ("SUNRPC: Fix a backchannel race")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-07-22 17:10:50 -04:00
Trond Myklebust 68514471ce SUNRPC: Fix a backchannel deadlock
xprt_alloc_bc_request() cannot call xprt_free_bc_request() without
deadlocking, since it already holds the xprt->bc_pa_lock.

Reported-by: Chuck Lever <chuck.lever@oracle.com>
Fixes: 0d2a970d0a ("SUNRPC: Fix a backchannel race")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-07-22 16:33:59 -04:00
Trond Myklebust 0d2a970d0a SUNRPC: Fix a backchannel race
We need to allow the server to send a new request immediately after we've
replied to the previous one. Right now, there is a window between the
send and the release of the old request in rpc_put_task(), where the
server could send us a new backchannel RPC call, and we have no
request to service it.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-06-05 11:15:43 -04:00
Trond Myklebust 1dddda86c0 SUNRPC: Clean up allocation and freeing of back channel requests
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-06-05 11:15:43 -04:00
Trond Myklebust 88de6af24f SUNRPC: Fix a memory leak in the backchannel code
req->rq_private_buf isn't initialised when xprt_setup_backchannel calls
xprt_free_allocation.

Fixes: fb7a0b9add ("nfs41: New backchannel helper routines")
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-06-02 08:55:28 -04:00
Chuck Lever 813b00d63f SUNRPC: Always manipulate rpc_rqst::rq_bc_pa_list under xprt->bc_pa_lock
Other code that accesses rq_bc_pa_list holds xprt->bc_pa_lock.
xprt_complete_bc_request() should do the same.

Fixes: 2ea24497a1 ("SUNRPC: RPC callbacks may be split . . .")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-02-13 17:41:10 -05:00
Jeff Layton f895b252d4 sunrpc: eliminate RPC_DEBUG
It's always set to whatever CONFIG_SUNRPC_DEBUG is, so just use that.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-11-24 17:31:46 -05:00
Peter Zijlstra 4e857c58ef arch: Mass conversion of smp_mb__*()
Mostly scripted conversion of the smp_mb__* barriers.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/n/tip-55dhyhocezdw1dg7u19hmh1u@git.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-arch@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-04-18 14:20:48 +02:00
Trond Myklebust 2ea24497a1 SUNRPC: RPC callbacks may be split across several TCP segments
Since TCP is a stream protocol, our callback read code needs to take into
account the fact that RPC callbacks are not always confined to a single
TCP segment.
This patch adds support for multiple TCP segments by ensuring that we
only remove the rpc_rqst structure from the 'free backchannel requests'
list once the data has been completely received. We rely on the fact
that TCP data is ordered for the duration of the connection.

Reported-by: shaobingqing <shaobingqing@bwstor.com.cn>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-02-11 14:01:20 -05:00
Trond Myklebust 628356791b SUNRPC: Fix potential memory scribble in xprt_free_bc_request()
The call to xprt_free_allocation() will call list_del() on
req->rq_bc_pa_list, which is not attached to a list.
This patch moves the list_del() out of xprt_free_allocation()
and into those callers that need it.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-02-11 13:56:54 -05:00
Weston Andros Adamson f30dfbba16 SUNRPC: remove two BUG_ON asserts
Replace two BUG_ON() calls checking the RPC_BC_PA_IN_USE flag with
WARN_ON_ONCE().

Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-11-04 14:43:41 -05:00
Weston Andros Adamson c4ded8d977 SUNRPC: remove BUG_ON from xprt_destroy_backchannel
If max_reqs is 0, do nothing besides the usual dprintks.

Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-11-04 14:43:40 -05:00
Weston Andros Adamson d24bab93e4 SUNRPC: return proper errno from backchannel_rqst
The one and only caller (in fs/nfs/nfs4client.c) uses the result
as an errno and would have interpreted an error as EPERM.

Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-11-01 11:50:53 -04:00
Ben Hutchings 2c53040f01 net: Fix (nearly-)kernel-doc comments for various functions
Fix incorrect start markers, wrapped summary lines, missing section
breaks, incorrect separators, and some name mismatches.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-07-10 23:13:45 -07:00
Trond Myklebust 09acfea5d8 SUNRPC: Fix a few sparse warnings
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>
2012-03-11 19:30:02 -04:00
Paul Gortmaker bc3b2d7fb9 net: Add export.h for EXPORT_SYMBOL/THIS_MODULE to non-modules
These files are non modular, but need to export symbols using
the macros now living in export.h -- call out the include so
that things won't break when we remove the implicit presence
of module.h from everywhere.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2011-10-31 19:30:30 -04:00
Trond Myklebust 0d961aa934 SUNRPC: Convert the backchannel exports to EXPORT_SYMBOL_GPL
Ensure that the backchannel exports conform to the existing sunrpc
practice.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-07-15 09:12:23 -04:00
Trond Myklebust 9e00abc3c2 SUNRPC: sunrpc should not explicitly depend on NFS config options
Change explicit references to CONFIG_NFS_V4_1 to implicit ones
Get rid of the unnecessary defines in backchannel_rqst.c and
bc_svc.c: the Makefile takes care of those dependency.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-07-15 09:12:23 -04:00
Tejun Heo 5a0e3ad6af include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-30 22:02:32 +09:00
Ricardo Labiaga e9f0298558 nfs41: sunrpc: xprt_alloc_bc_request() should not use spin_lock_bh()
xprt_alloc_bc_request() is always called in soft interrupt context.
Grab the spin_lock instead of the bottom half spin_lock.  Softirqs
do not preempt other softirqs running on the same processor, so there
is no need to disable bottom halves.

Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-06-20 14:55:39 -04:00
Ricardo Labiaga dd2b63d049 nfs41: Rename rq_received to rq_reply_bytes_recvd
The 'rq_received' member of 'struct rpc_rqst' is used to track when we
have received a reply to our request.  With v4.1, the backchannel
can now accept callback requests over the existing connection.  Rename
this field to make it clear that it is only used for tracking reply bytes
and not all bytes received on the connection.

Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
2009-06-17 14:11:40 -07:00
Ricardo Labiaga fb7a0b9add nfs41: New backchannel helper routines
This patch introduces support to setup the callback xprt on the client side.
It allocates/ destroys the preallocated memory structures used to process
backchannel requests.

At setup time, xprt_setup_backchannel() is invoked to allocate one or
more rpc_rqst structures and substructures.  This ensures that they
are available when an RPC callback arrives.  The rpc_rqst structures
are maintained in a linked list attached to the rpc_xprt structure.
We keep track of the number of allocations so that they can be correctly
removed when the channel is destroyed.

When an RPC callback arrives, xprt_alloc_bc_request() is invoked to
obtain a preallocated rpc_rqst structure.  An rpc_xprt structure is
returned, and its RPC_BC_PREALLOC_IN_USE bit is set in
rpc_xprt->bc_flags.  The structure is removed from the the list
since it is now in use, and it will be later added back when its
user is done with it.

After the RPC callback replies, the rpc_rqst structure is returned
by invoking xprt_free_bc_request().  This clears the
RPC_BC_PREALLOC_IN_USE bit and adds it back to the list, allowing it
to be reused by a subsequent RPC callback request.

To be consistent with the reception of RPC messages, the backchannel requests
should be placed into the 'struct rpc_rqst' rq_rcv_buf, which is then in turn
copied to the 'struct rpc_rqst' rq_private_buf.

[nfs41: Preallocate rpc_rqst receive buffer for handling callbacks]
Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[Update copyright notice and explain page allocation]
Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
2009-06-17 13:06:14 -07:00