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The save of the write offset was removed some time ago, so that
part of the comment is bogus.
The remainder is pretty self-evident.
So off with it!
Signed-off-by: Tom Haynes <Thomas.Haynes@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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The addition of lockdep code to write_seqcount_begin/end has lead to
a bunch of false positive claims of ABBA deadlocks with the so_lock
spinlock. Audits show that this simply cannot happen because the
read side code does not spin while holding so_lock.
Cc: <stable@vger.kernel.org> # 3.13.x
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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into linux-next
Pull NFS client side changes for RDMA from Anna Schumaker
These patches are mostly cleanups and bugfixes for using RDMA as an
over-the-wire transport.
Highlights include:
- Remove obsolete memory registration modes.
- Removing BUG_ON()s to keep client's running.
- Fix deadlocks, NULL-pointer dereferences, and memory leaks.
* tag 'nfs-rdma-3.16' of git://git.linux-nfs.org/projects/anna/nfs-rdma: (24 commits)
xprtrdma: Disconnect on registration failure
xprtrdma: Remove BUG_ON() call sites
xprtrdma: Avoid deadlock when credit window is reset
SUNRPC: Move congestion window constants to header file
xprtrdma: Reset connection timeout after successful reconnect
xprtrdma: Use macros for reconnection timeout constants
xprtrdma: Allocate missing pagelist
xprtrdma: Remove Tavor MTU setting
xprtrdma: Ensure ia->ri_id->qp is not NULL when reconnecting
xprtrdma: Reduce the number of hardway buffer allocations
xprtrdma: Limit work done by completion handler
xprtrmda: Reduce calls to ib_poll_cq() in completion handlers
xprtrmda: Reduce lock contention in completion handlers
xprtrdma: Split the completion queue
xprtrdma: Make rpcrdma_ep_destroy() return void
xprtrdma: Simplify rpcrdma_deregister_external() synopsis
xprtrdma: mount reports "Invalid mount option" if memreg mode not supported
xprtrdma: Fall back to MTHCAFMR when FRMR is not supported
xprtrdma: Remove REGISTER memory registration mode
xprtrdma: Remove MEMWINDOWS registration modes
...
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If rpcrdma_register_external() fails during request marshaling, the
current RPC request is killed. Instead, this RPC should be retried
after reconnecting the transport instance.
The most likely reason for registration failure with FRMR is a
failed post_send, which would be due to a remote transport
disconnect or memory exhaustion. These issues can be recovered
by a retry.
Problems encountered in the marshaling logic itself will not be
corrected by trying again, so these should still kill a request.
Now that we've added a clean exit for marshaling errors, take the
opportunity to defang some BUG_ON's.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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If an error occurs in the marshaling logic, fail the RPC request
being processed, but leave the client running.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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Update the cwnd while processing the server's reply. Otherwise the
next task on the xprt_sending queue is still subject to the old
credit window. Currently, no task is awoken if the old congestion
window is still exceeded, even if the new window is larger, and a
deadlock results.
This is an issue during a transport reconnect. Servers don't
normally shrink the credit window, but the client does reset it to
1 when reconnecting so the server can safely grow it again.
As a minor optimization, remove the hack of grabbing the initial
cwnd size (which happens to be RPC_CWNDSCALE) and using that value
as the congestion scaling factor. The scaling value is invariant,
and we are better off without the multiplication operation.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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I would like to use one of the RPC client's congestion algorithm
constants in transport-specific code.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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If the new connection is able to make forward progress, reset the
re-establish timeout. Otherwise it keeps growing even if disconnect
events are rare.
The same behavior as TCP is adopted: reconnect immediately if the
transport instance has been able to make some forward progress.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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Clean up: Ensure the same max and min constant values are used
everywhere when setting reconnect timeouts.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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GETACL relies on transport layer to alloc memory for reply buffer.
However xprtrdma assumes that the reply buffer (pagelist) has been
pre-allocated in upper layer. This problem was reported by IOL OFA lab
test on PPC.
Signed-off-by: Shirley Ma <shirley.ma@oracle.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Edward Mossman <emossman@iol.unh.edu>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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Clean up. Remove HCA-specific clutter in xprtrdma, which is
supposed to be device-independent.
Hal Rosenstock <hal@dev.mellanox.co.il> observes:
> Note that there is OpenSM option (enable_quirks) to return 1K MTU
> in SA PathRecord responses for Tavor so that can be used for this.
> The default setting for enable_quirks is FALSE so that would need
> changing.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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Devesh Sharma <Devesh.Sharma@Emulex.Com> reports that after a
disconnect, his HCA is failing to create a fresh QP, leaving
ia_ri->ri_id->qp set to NULL. But xprtrdma still allows RPCs to
wake up and post LOCAL_INV as they exit, causing an oops.
rpcrdma_ep_connect() is allowing the wake-up by leaking the QP
creation error code (-EPERM in this case) to the RPC client's
generic layer. xprt_connect_status() does not recognize -EPERM, so
it kills pending RPC tasks immediately rather than retrying the
connect.
Re-arrange the QP creation logic so that when it fails on reconnect,
it leaves ->qp with the old QP rather than NULL. If pending RPC
tasks wake and exit, LOCAL_INV work requests will flush rather than
oops.
On initial connect, leaving ->qp == NULL is OK, since there are no
pending RPCs that might use ->qp. But be sure not to try to destroy
a NULL QP when rpcrdma_ep_connect() is retried.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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While marshaling an RPC/RDMA request, the inline_{rsize,wsize}
settings determine whether an inline request is used, or whether
read or write chunks lists are built. The current default value of
these settings is 1024. Any RPC request smaller than 1024 bytes is
sent to the NFS server completely inline.
rpcrdma_buffer_create() allocates and pre-registers a set of RPC
buffers for each transport instance, also based on the inline rsize
and wsize settings.
RPC/RDMA requests and replies are built in these buffers. However,
if an RPC/RDMA request is expected to be larger than 1024, a buffer
has to be allocated and registered for that RPC, and deregistered
and released when the RPC is complete. This is known has a
"hardway allocation."
Since the introduction of NFSv4, the size of RPC requests has become
larger, and hardway allocations are thus more frequent. Hardway
allocations are significant overhead, and they waste the existing
RPC buffers pre-allocated by rpcrdma_buffer_create().
We'd like fewer hardway allocations.
Increasing the size of the pre-registered buffers is the most direct
way to do this. However, a blanket increase of the inline thresholds
has interoperability consequences.
On my 64-bit system, rpcrdma_buffer_create() requests roughly 7000
bytes for each RPC request buffer, using kmalloc(). Due to internal
fragmentation, this wastes nearly 1200 bytes because kmalloc()
already returns an 8192-byte piece of memory for a 7000-byte
allocation request, though the extra space remains unused.
So let's round up the size of the pre-allocated buffers, and make
use of the unused space in the kmalloc'd memory.
This change reduces the amount of hardway allocated memory for an
NFSv4 general connectathon run from 1322092 to 9472 bytes (99%).
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>
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Sagi Grimberg <sagig@dev.mellanox.co.il> points out that a steady
stream of CQ events could starve other work because of the boundless
loop pooling in rpcrdma_{send,recv}_poll().
Instead of a (potentially infinite) while loop, return after
collecting a budgeted number of completions.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Acked-by: Sagi Grimberg <sagig@dev.mellanox.co.il>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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Change the completion handlers to grab up to 16 items per
ib_poll_cq() call. No extra ib_poll_cq() is needed if fewer than 16
items are returned.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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Skip the ib_poll_cq() after re-arming, if the provider knows there
are no additional items waiting. (Have a look at commit ed23a727 for
more details).
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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The current CQ handler uses the ib_wc.opcode field to distinguish
between event types. However, the contents of that field are not
reliable if the completion status is not IB_WC_SUCCESS.
When an error completion occurs on a send event, the CQ handler
schedules a tasklet with something that is not a struct rpcrdma_rep.
This is never correct behavior, and sometimes it results in a panic.
To resolve this issue, split the completion queue into a send CQ and
a receive CQ. The send CQ handler now handles only struct rpcrdma_mw
wr_id's, and the receive CQ handler now handles only struct
rpcrdma_rep wr_id's.
Fix suggested by Shirley Ma <shirley.ma@oracle.com>
Reported-by: Rafael Reiter <rafael.reiter@ims.co.at>
Fixes: 5c635e09cec0feeeb310968e51dad01040244851
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=73211
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Klemens Senn <klemens.senn@ims.co.at>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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Clean up: rpcrdma_ep_destroy() returns a value that is used
only to print a debugging message. rpcrdma_ep_destroy() already
prints debugging messages in all error cases.
Make rpcrdma_ep_destroy() return void instead.
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>
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Clean up: All remaining callers of rpcrdma_deregister_external()
pass NULL as the last argument, so remove that argument.
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>
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If the selected memory registration mode is not supported by the
underlying provider/HCA, the NFS mount command reports that there was
an invalid mount option, and fails. This is misleading.
Reporting a problem allocating memory is a lot closer to the truth.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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An audit of in-kernel RDMA providers that do not support the FRMR
memory registration shows that several of them support MTHCAFMR.
Prefer MTHCAFMR when FRMR is not supported.
If MTHCAFMR is not supported, only then choose ALLPHYSICAL.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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All kernel RDMA providers except amso1100 support either MTHCAFMR
or FRMR, both of which are faster than REGISTER. amso1100 can
continue to use ALLPHYSICAL.
The only other ULP consumer in the kernel that uses the reg_phys_mr
verb is Lustre.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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The MEMWINDOWS and MEMWINDOWS_ASYNC memory registration modes were
intended as stop-gap modes before the introduction of FRMR. They
are now considered obsolete.
MEMWINDOWS_ASYNC is also considered unsafe because it can leave
client memory registered and exposed for an indeterminant time after
each I/O.
At this point, the MEMWINDOWS modes add needless complexity, so
remove them.
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>
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Clean up: This memory registration mode is slow and was never
meant for use in production environments. Remove it to reduce
implementation complexity.
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>
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An IB provider can invoke rpcrdma_conn_func() in an IRQ context,
thus rpcrdma_conn_func() cannot be allowed to directly invoke
generic RPC functions like xprt_wake_pending_tasks().
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>
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Two memory region leaks were found during testing:
1. rpcrdma_buffer_create: While allocating RPCRDMA_FRMR's
ib_alloc_fast_reg_mr is called and then ib_alloc_fast_reg_page_list is
called. If ib_alloc_fast_reg_page_list returns an error it bails out of
the routine dropping the last ib_alloc_fast_reg_mr frmr region creating a
memory leak. Added code to dereg the last frmr if
ib_alloc_fast_reg_page_list fails.
2. rpcrdma_buffer_destroy: While cleaning up, the routine will only free
the MR's on the rb_mws list if there are rb_send_bufs present. However, in
rpcrdma_buffer_create while the rb_mws list is being built if one of the MR
allocation requests fail after some MR's have been allocated on the rb_mws
list the routine never gets to create any rb_send_bufs but instead jumps to
the rpcrdma_buffer_destroy routine which will never free the MR's on rb_mws
list because the rb_send_bufs were never created. This leaks all the MR's
on the rb_mws list that were created prior to one of the MR allocations
failing.
Issue(2) was seen during testing. Our adapter had a finite number of MR's
available and we created enough connections to where we saw an MR
allocation failure on our Nth NFS connection request. After the kernel
cleaned up the resources it had allocated for the Nth connection we noticed
that FMR's had been leaked due to the coding error described above.
Issue(1) was seen during a code review while debugging issue(2).
Signed-off-by: Allen Andrews <allen.andrews@emulex.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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Some rdma devices don't support a fast register page list depth of
at least RPCRDMA_MAX_DATA_SEGS. So xprtrdma needs to chunk its fast
register regions according to the minimum of the device max supported
depth or RPCRDMA_MAX_DATA_SEGS.
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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The object and block layouts already exist in their own
subdirectories. This patch completes the set!
Note that as a layout denotes nfs4 already, I stripped
that prefix out of the file names.
Signed-off-by: Tom Haynes <Thomas.Haynes@primarydata.com>
Acked-by: Jeff Layton <jlayton@poochiereds.net>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Return the NULL pointer when the allocation fails.
Cc: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Return the NULL pointer when the allocation fails.
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: <stable@vger.kernel.org> # 3.5.x
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Those flags are obsolete and checking them can incorrectly cause
remount operations to fail.
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Place the call to resend the failed GETATTR under the error handler so that
when appropriate, the GETATTR is retried more than once.
The server can fail the GETATTR op in the OPEN compound with a recoverable
error such as NFS4ERR_DELAY. In the case of an O_EXCL open, the server has
created the file, so a retrans of the OPEN call will fail with NFS4ERR_EXIST.
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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We cannot allow nfs_page_group_lock to use TASK_KILLABLE here, since
the loop would cause a busy wait if somebody kills the task.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Handle the case where nfs_create_request() returns an error.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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rpc_malloc() allocates with GFP_NOWAIT without making any attempt at
reclaim so it easily fails when low on memory. This ends up spamming the
kernel log:
SLAB: Unable to allocate memory on node 0 (gfp=0x4000)
cache: kmalloc-8192, object size: 8192, order: 1
node 0: slabs: 207/207, objs: 207/207, free: 0
rekonq: page allocation failure: order:1, mode:0x204000
CPU: 2 PID: 14321 Comm: rekonq Tainted: G O 3.15.0-rc3-12.gfc9498b-desktop+ #6
Hardware name: System manufacturer System Product Name/M4A785TD-V EVO, BIOS 2105 07/23/2010
0000000000000000 ffff880010ff17d0 ffffffff815e693c 0000000000204000
ffff880010ff1858 ffffffff81137bd2 0000000000000000 0000001000000000
ffff88011ffebc38 0000000000000001 0000000000204000 ffff88011ffea000
Call Trace:
[<ffffffff815e693c>] dump_stack+0x4d/0x6f
[<ffffffff81137bd2>] warn_alloc_failed+0xd2/0x140
[<ffffffff8113be19>] __alloc_pages_nodemask+0x7e9/0xa30
[<ffffffff811824a8>] kmem_getpages+0x58/0x140
[<ffffffff81183de6>] fallback_alloc+0x1d6/0x210
[<ffffffff81183be3>] ____cache_alloc_node+0x123/0x150
[<ffffffff81185953>] __kmalloc+0x203/0x490
[<ffffffffa06b0ee2>] rpc_malloc+0x32/0xa0 [sunrpc]
[<ffffffffa06a6999>] call_allocate+0xb9/0x170 [sunrpc]
[<ffffffffa06b19d8>] __rpc_execute+0x88/0x460 [sunrpc]
[<ffffffffa06b2da9>] rpc_execute+0x59/0xc0 [sunrpc]
[<ffffffffa06a932b>] rpc_run_task+0x6b/0x90 [sunrpc]
[<ffffffffa077b5c1>] nfs4_call_sync_sequence+0x51/0x80 [nfsv4]
[<ffffffffa077d45d>] _nfs4_do_setattr+0x1ed/0x280 [nfsv4]
[<ffffffffa0782a72>] nfs4_do_setattr+0x72/0x180 [nfsv4]
[<ffffffffa078334c>] nfs4_proc_setattr+0xbc/0x140 [nfsv4]
[<ffffffffa074a7e8>] nfs_setattr+0xd8/0x240 [nfs]
[<ffffffff811baa71>] notify_change+0x231/0x380
[<ffffffff8119cf5c>] chmod_common+0xfc/0x120
[<ffffffff8119df80>] SyS_chmod+0x40/0x90
[<ffffffff815f4cfd>] system_call_fastpath+0x1a/0x1f
...
If the allocation fails, simply return NULL and avoid spamming the kernel
log.
Reported-by: Marc Dietrich <marvin24@gmx.de>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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nfs_read_completion relied on the fact that there was a 1:1 mapping
of page to nfs_request, but this has now changed.
Regions not covered by a request have already been zeroed elsewhere.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Use the new pg_test interface to adjust requests to fit in the current
stripe / segment.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Remove alignment checks that would revert to MDS and change pg_test
to return the max ammount left in the segment (or other pg_test call)
up to size of passed request, or 0 if no space is left.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Support direct requests that span multiple pnfs data servers by
comparing nfs_pgio_header->verf to a cached verf in pnfs_commit_bucket.
Continue to use dreq->verf if the MDS is used / non-pNFS.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Since the ability to split pages into subpage requests has been added,
nfs_pgio_header->rpc_list only ever has one pgio data.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Use the newly added support for multiple requests per page for
rsize/wsize < PAGE_SIZE, instead of having multiple read / write
data structures per pageio header.
This allows us to get rid of nfs_pgio_multi.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Now that pg_test can change the size of the request (by returning a non-zero
size smaller than the request), pg_test functions that call other
pg_test functions must return the minimum of the result - or 0 if any fail.
Also clean up the logic of some pg_test functions so that all checks are
for contitions where coalescing is not possible.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Remove check that the request covers a whole page.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Remove unneeded else statement and clean up how commit info
dataserver buckets are replaced.
Suggested-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Change how nfs_mark_uptodate checks to see if writes cover a whole page.
This patch should have no effect yet since all page groups currently
have one request, but will come into play when pg_test functions are
modified to split pages into sub-page regions.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Operations that modify state for a whole page must be syncronized across
all requests within a page group. In the write path, this is calling
end_page_writeback and removing the head request from an inode.
Both of these operations should not be called until all requests
in a page group have reached the point where they would call them.
This patch should have no effect yet since all page groups currently
have one request, but will come into play when pg_test functions are
modified to split pages into sub-page regions.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Operations that modify state for a whole page must be syncronized across
all requests within a page group. In the read path, this is calling
unlock_page and SetPageUptodate. Both of these functions should not be
called until all requests in a page group have reached the point where
they would call them.
This patch should have no effect yet since all page groups currently
have one request, but will come into play when pg_test functions are
modified to split pages into sub-page regions.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Add "page groups" - a circular list of nfs requests (struct nfs_page)
that all reference the same page. This gives nfs read and write paths
the ability to account for sub-page regions independently. This
somewhat follows the design of struct buffer_head's sub-page
accounting.
Only "head" requests are ever added/removed from the inode list in
the buffered write path. "head" and "sub" requests are treated the
same through the read path and the rest of the write/commit path.
Requests are given an extra reference across the life of the list.
Page groups are never rejoined after being split. If the read/write
request fails and the client falls back to another path (ie revert
to MDS in PNFS case), the already split requests are pushed through
the recoalescing code again, which may split them further and then
coalesce them into properly sized requests on the wire. Fragmentation
shouldn't be a problem with the current design, because we flush all
requests in page group when a non-contiguous request is added, so
the only time resplitting should occur is on a resend of a read or
write.
This patch lays the groundwork for sub-page splitting, but does not
actually do any splitting. For now all page groups have one request
as pg_test functions don't yet split pages. There are several related
patches that are needed support multiple requests per page group.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Call nfs_can_coalesce_requests for every request, even the first one.
This is needed for future patches to give pg_test a way to inform
add_request to reduce the size of the request.
Now @prev can be null in nfs_can_coalesce_requests and pg_test functions.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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This is a step toward allowing pg_test to inform the the
coalescing code to reduce the size of requests so they may fit in
whatever scheme the pg_test callback wants to define.
For now, just return the size of the request if there is space, or 0
if there is not. This shouldn't change any behavior as it acts
the same as when the pg_test functions returned bool.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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