Commit graph

78 commits

Author SHA1 Message Date
Tom Talpey
b3cd8d45a7 RPC/RDMA: optionally emit useful transport info upon connect/disconnect.
Signed-off-by: Tom Talpey <talpey@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2008-10-10 15:13:59 -04:00
Tom Talpey
5f37d561e0 RPC/RDMA: reformat a debug printk to keep lines together.
The send marshaling code split a particular dprintk across two
lines, which makes it hard to extract from logfiles.

Signed-off-by: Tom Talpey <talpey@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2008-10-10 15:13:42 -04:00
Tom Talpey
5675add36e RPC/RDMA: harden connection logic against missing/late rdma_cm upcalls.
Add defensive timeouts to wait_for_completion() calls in RDMA
address resolution, and make them interruptible. Fix the timeout
units to milliseconds (formerly jiffies) and move to private header.

Signed-off-by: Tom Talpey <talpey@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2008-10-10 15:13:31 -04:00
Tom Talpey
1a954051b0 RPC/RDMA: fix connect/reconnect resource leak.
The RPC/RDMA code can leak RDMA connection manager endpoints in
certain error cases on connect. Don't signal unwanted events,
and be certain to destroy any allocated qp.

Signed-off-by: Tom Talpey <talpey@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2008-10-10 15:13:02 -04:00
Tom Talpey
926449ba66 RPC/RDMA: return a consistent error, when connect fails.
The xprt_connect call path does not expect such errors as ECONNREFUSED
to be returned from failed transport connection attempts, otherwise it
translates them to EIO and signals fatal errors. For example, mount.nfs
prints simply "internal error". Translate all such errors to ENOTCONN
from RPC/RDMA to match sockets behavior.

Signed-off-by: Tom Talpey <talpey@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2008-10-10 15:12:44 -04:00
Tom Talpey
9191ca3b38 RPC/RDMA: adhere to protocol for unpadded client trailing write chunks.
The RPC/RDMA protocol allows clients and servers to avoid RDMA
operations for data which is purely the result of XDR padding.
On the client, automatically insert the necessary padding for
such server replies, and optionally don't marshal such chunks.

Signed-off-by: Tom Talpey <talpey@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2008-10-10 15:12:33 -04:00
Tom Talpey
fee08caf94 RPC/RDMA: avoid an oops due to disconnect racing with async upcalls.
RDMA disconnects yield an upcall from the RDMA connection manager,
which can race with rpc transport close, e.g. on ^C of a mount.
Ensure any rdma cm_id and qp are fully destroyed before continuing.

Signed-off-by: Tom Talpey <talpey@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2008-10-10 15:11:40 -04:00
Tom Talpey
ad0e9e01da RPC/RDMA: maintain the RPC task bytes-sent statistic.
Signed-off-by: Tom Talpey <talpey@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2008-10-10 15:10:40 -04:00
Tom Talpey
575448bd36 RPC/RDMA: suppress retransmit on RPC/RDMA clients.
An RPC/RDMA client cannot retransmit on an unbroken connection,
doing so violates its flow control with the server.

Signed-off-by: Tom Talpey <talpey@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2008-10-10 15:10:36 -04:00
Tom Tucker
b334eaabf4 RPC/RDMA: fix connection IRD/ORD setting
This logic sets the connection parameter that configures the local device
and informs the remote peer how many concurrent incoming RDMA_READ
requests are supported. The original logic didn't really do what was
intended for two reasons:

- The max number supported by the device is typically smaller than
any one factor in the calculation used, and

- The field in the connection parameter structure where the value is
stored is a u8 and always overflows for the default settings.

So what really happens is the value requested for responder resources
is the left over 8 bits from the "desired value". If the desired value
happened to be a multiple of 256, the result was zero and it wouldn't
connect at all.

Given the above and the fact that max_requests is almost always larger
than the max responder resources supported by the adapter, this patch
simplifies this logic and simply requests the max supported by the device,
subject to a reasonable limit.

This bug was found by Jim Schutt at Sandia.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Acked-by: Tom Talpey <talpey@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2008-10-10 15:09:56 -04:00
Tom Talpey
3197d309f5 RPC/RDMA: support FRMR client memory registration.
Configure, detect and use "fastreg" support from IB/iWARP verbs
layer to perform RPC/RDMA memory registration.

Make FRMR the default memreg mode (will fall back if not supported
by the selected RDMA adapter).

This allows full and optimal operation over the cxgb3 adapter, and others.

Signed-off-by: Tom Talpey <talpey@netapp.com>
Acked-by: Tom Tucker <tom@opengridcomputing.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2008-10-10 15:09:34 -04:00
Tom Talpey
bd7ed1d133 RPC/RDMA: check selected memory registration mode at runtime.
At transport creation, check for, and use, any local dma lkey.
Then, check that the selected memory registration mode is in fact
supported by the RDMA adapter selected for the mount. Fall back
to best alternative if not.

Signed-off-by: Tom Talpey <talpey@netapp.com>
Acked-by: Tom Tucker <tom@opengridcomputing.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2008-10-10 15:09:26 -04:00
Tom Talpey
fe9053b30b RPC/RDMA: add data types and new FRMR memory registration enum.
Internal RPC/RDMA structure updates in preparation for FRMR support.

Signed-off-by: Tom Talpey <talpey@netapp.com>
Acked-by: Tom Tucker <tom@opengridcomputing.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2008-10-10 15:09:24 -04:00
Tom Talpey
8d4ba0347c RPC/RDMA: refactor the inline memory registration code.
Refactor the memory registration and deregistration routines.
This saves stack space, makes the code more readable and prepares
to add the new FRMR registration methods.

Signed-off-by: Tom Talpey <talpey@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2008-10-10 15:09:16 -04:00
Tom Tucker
24b8b44780 svcrdma: Fix race between svc_rdma_recvfrom thread and the dto_tasklet
RDMA_READ completions are kept on a separate queue from the general
I/O request queue. Since a separate lock is used to protect the RDMA_READ
completion queue, a race exists between the dto_tasklet and the
svc_rdma_recvfrom thread where the dto_tasklet sets the XPT_DATA
bit and adds I/O to the read-completion queue. Concurrently, the
recvfrom thread checks the generic queue, finds it empty and resets
the XPT_DATA bit. A subsequent svc_xprt_enqueue will fail to enqueue
the transport for I/O and cause the transport to "stall".

The fix is to protect both lists with the same lock and set the XPT_DATA
bit with this lock held.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
2008-08-13 16:57:31 -04:00
FUJITA Tomonori
8d8bb39b9e dma-mapping: add the device argument to dma_mapping_error()
Add per-device dma_mapping_ops support for CONFIG_X86_64 as POWER
architecture does:

This enables us to cleanly fix the Calgary IOMMU issue that some devices
are not behind the IOMMU (http://lkml.org/lkml/2008/5/8/423).

I think that per-device dma_mapping_ops support would be also helpful for
KVM people to support PCI passthrough but Andi thinks that this makes it
difficult to support the PCI passthrough (see the above thread).  So I
CC'ed this to KVM camp.  Comments are appreciated.

A pointer to dma_mapping_ops to struct dev_archdata is added.  If the
pointer is non NULL, DMA operations in asm/dma-mapping.h use it.  If it's
NULL, the system-wide dma_ops pointer is used as before.

If it's useful for KVM people, I plan to implement a mechanism to register
a hook called when a new pci (or dma capable) device is created (it works
with hot plugging).  It enables IOMMUs to set up an appropriate
dma_mapping_ops per device.

The major obstacle is that dma_mapping_error doesn't take a pointer to the
device unlike other DMA operations.  So x86 can't have dma_mapping_ops per
device.  Note all the POWER IOMMUs use the same dma_mapping_error function
so this is not a problem for POWER but x86 IOMMUs use different
dma_mapping_error functions.

The first patch adds the device argument to dma_mapping_error.  The patch
is trivial but large since it touches lots of drivers and dma-mapping.h in
all the architecture.

This patch:

dma_mapping_error() doesn't take a pointer to the device unlike other DMA
operations.  So we can't have dma_mapping_ops per device.

Note that POWER already has dma_mapping_ops per device but all the POWER
IOMMUs use the same dma_mapping_error function.  x86 IOMMUs use device
argument.

[akpm@linux-foundation.org: fix sge]
[akpm@linux-foundation.org: fix svc_rdma]
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: fix bnx2x]
[akpm@linux-foundation.org: fix s2io]
[akpm@linux-foundation.org: fix pasemi_mac]
[akpm@linux-foundation.org: fix sdhci]
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: fix sparc]
[akpm@linux-foundation.org: fix ibmvscsi]
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Muli Ben-Yehuda <muli@il.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Avi Kivity <avi@qumranet.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-26 12:00:03 -07:00
Tom Tucker
8948896c9e svcrdma: Change WR context get/put to use the kmem cache
Change the WR context pool to be shared across mount points. This
reduces the RDMA transport memory footprint significantly since
idle mounts don't consume WR context memory.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-07-02 15:02:02 -05:00
Tom Tucker
bf5927d84e svcrdma: Create a kmem cache for the WR contexts
Create a kmem cache to hold WR contexts. Next we will convert
the WR context get and put services to use this kmem cache.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-07-02 15:02:01 -05:00
Tom Tucker
902a94e088 svcrdma: Add flush_scheduled_work to module exit function
Make certain all transports pending free are flushed from the wq
before unloading the module.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-07-02 15:02:00 -05:00
Tom Tucker
36ef25e464 svcrdma: Limit ORD based on client's advertised IRD
When adapters have differing IRD limits, the RDMA transport will fail to
connect properly. The RDMA transport should use the client's advertised
inbound read limit when computing its outbound read limit. For iWARP
transports, there is currently no standard for exchanging IRD/ORD
during connection establishment so the 'responder_resources' field in the
connect event is the local device's limit. The RDMA transport can be
configured to use a smaller ORD by writing the desired number to the
/proc/sys/sunrpc/svc_rdma/max_outbound_read_requests file.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-07-02 15:01:59 -05:00
Tom Tucker
94dba4918d svcrdma: Remove unneeded spin locks from __svc_rdma_free
At the time __svc_rdma_free is called, we are guaranteed that all references
to this transport are gone. There is, therefore, no need to protect the
resource lists with a spin lock.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-07-02 15:01:57 -05:00
Tom Tucker
87295b6c5c svcrdma: Add dma map count and WARN_ON
Add a dma map count in order to verify that all DMA mapping resources
have been freed when the transport is closed.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-07-02 15:01:56 -05:00
Tom Tucker
e6ab914371 svcrdma: Move the DMA unmap logic to the CQ handler
Separate DMA unmap from context destruction and perform DMA unmapping
in the SQ/RQ CQ reap functions. This is necessary to support software
based RDMA implementations that actually copy the data in their
ib_dma_unmap callback functions and architectures that don't have
cache coherent I/O busses.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-07-02 15:01:55 -05:00
Tom Tucker
f820c57ebf svcrdma: Use reply and chunk map for RDMA_READ processing
Modify the RDMA_READ processing to use the reply and chunk list mapping data
types. Also add a special purpose 'hdr_count' field in in the context to hold
the header page count instead of overloading the SGE length field and
corrupting the DMA map length.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-07-02 15:01:55 -05:00
Tom Tucker
34d16e42a6 svcrdma: Use RPC reply map for RDMA_WRITE processing
Use the new svc_rdma_req_map data type for mapping the client side memory
to the server side memory. Move the DMA mapping to the context pointed to
by each WR individually so that it is unmapped after the WR completes.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-07-02 15:01:54 -05:00
Tom Tucker
ab96dddbed svcrdma: Add a type for keeping NFS RPC mapping
Create a new data structure to hold the remote client address space
to local server address space mapping.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-07-02 15:01:53 -05:00
Tom Tucker
a6f911c04e svcrdma: Verify read-list fits within RPCSVC_MAXPAGES
A RDMA read-list cannot contain more elements than RPCSVC_MAXPAGES or
it will overflow the DTO context. Verify this when processing the
protocol header.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:34:02 -05:00
Tom Tucker
008fdbc571 svcrdma: Change svc_rdma_send_error return type to void
The svc_rdma_send_error function is called when an RPCRDMA protocol
error is detected. This function attempts to post an error reply message.
Since an error posting to a transport in error is ignored, change
the return type to void.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:34:01 -05:00
Tom Tucker
af261af4db svcrdma: Copy transport address and arm CQ before calling rdma_accept
This race was found by inspection. Messages can be received from the peer
immediately following the rdma_accept call, however, the CQ have not yet
been armed and the transport address has not yet been set.

Set the transport address in the connect request handler and arm the CQ
prior to calling rdma_accept.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:34:00 -05:00
Tom Tucker
69500c43b4 svcrdma: Set rqstp transport address in rdma_read_complete function
The rdma_read_complete function needs to copy the rqstp transport address
from the transport. Failure to do so can result in using the wrong
authentication method for the RPC or bug checking if the rqstp address
is not valid.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:33:59 -05:00
Tom Tucker
97a3df382e svcrdma: Use ib verbs version of dma_unmap
Use the ib_verbs version of the dma_unmap service in the
svc_rdma_put_context function. This should support providers
using software rdma.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:33:58 -05:00
Tom Tucker
356d0a1519 svcrdma: Cleanup queued, but unprocessed I/O in svc_rdma_free
When the transport is closing, the DTO tasklet may queue data
that never gets processed. Clean up resources associated with
this I/O.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:33:57 -05:00
Tom Tucker
1711386c62 svcrdma: Move the QP and cm_id destruction to svc_rdma_free
Move the destruction of the QP and CM_ID to the free path so that the
QP cleanup code doesn't race with the dto_tasklet handling flushed WR.
The QP reference is not needed because we now have a reference for
every WR.

Also add a guard in the SQ and RQ completion handlers to ignore
calls generated by some providers when the QP is destroyed.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:33:56 -05:00
Tom Tucker
0905c0f0a2 svcrdma: Add reference for each SQ/RQ WR
Add a reference on the transport for every outstanding WR.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:33:55 -05:00
Tom Tucker
8da91ea8de svcrdma: Move destroy to kernel thread
Some providers may wait while destroying adapter resources.
Since it is possible that the last reference is put on the
dto_tasklet, the actual destroy must be scheduled as a work item.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:33:54 -05:00
Tom Tucker
47698e083e svcrdma: Shrink scope of spinlock on RQ CQ
The rq_cq_reap function is only called from the dto_tasklet. The
only resource shared with other threads is the sc_rq_dto_q. Move the
spin lock to protect only this list.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:33:53 -05:00
Tom Tucker
8740767376 svcrdma: Use standard Linux lists for context cache
Replace the one-off linked list implementation used to implement the
context cache with the standard Linux list_head lists. Add a context
counter to catch resource leaks. A WARN_ON will be added later to
ensure that we've freed all contexts.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:33:52 -05:00
Tom Tucker
02e7452de7 svcrdma: Simplify RDMA_READ deferral buffer management
An NFS_WRITE requires a set of RDMA_READ requests to fetch the write
data from the client. There are two principal pieces of data that
need to be tracked: the list of pages that comprise the completed RPC
and the SGE of dma mapped pages to refer to this list of pages. Previously
this whole bit was managed as a linked list of contexts with the
context containing the page list buried in this list. This patch
simplifies this processing by not keeping a linked list, but rather only
a pionter from the last submitted RDMA_READ's context to the context
that maps the set of pages that describe the RPC.  This significantly
simplifies this code path. SGE contexts are cleaned up inline in the DTO
path instead of at read completion time.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:33:51 -05:00
Tom Tucker
10a38c33f4 svcrdma: Remove unused READ_DONE context flags bit
The RDMACTXT_F_READ_DONE bit is not longer used. Remove it.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:33:50 -05:00
Tom Tucker
d16d40093a svcrdma: Return error from rdma_read_xdr so caller knows to free context
The rdma_read_xdr function did not discriminate between no read-list and
an error posting the read-list. This results in a leak of a page if there
is an error posting the read-list.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:33:49 -05:00
Tom Tucker
58e8f62137 svcrdma: Fix error handling during listening endpoint creation
A listening endpoint isn't known to the generic transport switch until
the svc_create_xprt function returns without error. Calling
svc_xprt_put within the xpo_create function causes the module reference
count to be erroneously decremented.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:33:48 -05:00
Tom Tucker
5ac461a6f0 svcrdma: Free context on post_recv error in send_reply
If an error is encountered trying to post a recv buffer in send_reply,
free the passed in context. Return an error to the caller so it is
aware that the request was not posted.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:33:47 -05:00
Tom Tucker
05a0826a6e svcrdma: Free context on ib_post_recv error
If there is an error posting the recv WR to the RQ, free the
context associated with the WR. This would leak a context when
asynchronous errors occurred on the transport while conccurent threads
were processing their RPC.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:33:47 -05:00
Tom Tucker
120693d12c svcrdma: Add put of connection ESTABLISHED reference in rdma_cma_handler
The svcrdma transport takes a reference when it gets the ESTABLISHED
event from the provider. This reference is supposed to be removed when
the DISCONNECT event is received, however, the call to svc_xprt_put
was missing in the switch statement. This results in the memory
associated with the transport never being freed.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:33:46 -05:00
Tom Tucker
9d6347acd2 svcrdma: Fix return value in svc_rdma_send
Fix the return value on close to -ENOTCONN so caller knows to free context.
Also if a thread is waiting for free SQ space, check for close when waking
to avoid posting WR to a closing transport.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:33:45 -05:00
Tom Tucker
dbcd00eba9 svcrdma: Fix race with dto_tasklet in svc_rdma_send
The svc_rdma_send function will attempt to reap SQ WR to make room for
a new request if it finds the SQ full. This function races with the
dto_tasklet that also reaps SQ WR. To avoid polling and arming the CQ
unnecessarily move the test_and_clear_bit of the RDMAXPRT_SQ_PENDING
flag and arming of the CQ to the sq_cq_reap function.

Refactor the rq_cq_reap function to match sq_cq_reap so that the
code is easier to follow.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:33:44 -05:00
Tom Tucker
0e7f011a19 svcrdma: Simplify receive buffer posting
The svcrdma transport provider currently allocates receive buffers
to the RQ through the xpo_release_rqst method. This approach is overly
complicated since it means that the rqstp rq_xprt_ctxt has to be
selectively set based on whether the RPC is going to be processed
immediately or deferred. Instead, just post the receive buffer when
we are certain that we are replying in the send_reply function.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
2008-05-19 07:33:43 -05:00
Tom Tucker
830bb59b6e SVCRDMA: Add check for XPT_CLOSE in svc_rdma_send
SVCRDMA: Add check for XPT_CLOSE in svc_rdma_send

The svcrdma transport can crash if a send is waiting for an
empty SQ slot and the connection is closed due to an asynchronous error.
The crash is caused when svc_rdma_send attempts to send on a deleted
QP.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
2008-04-23 16:13:40 -04:00
Roland Dreier
0f39cf3d54 IB/core: Add support for "send with invalidate" work requests
Add a new IB_WR_SEND_WITH_INV send opcode that can be used to mark a
"send with invalidate" work request as defined in the iWARP verbs and
the InfiniBand base memory management extensions.  Also put "imm_data"
and a new "invalidate_rkey" member in a new "ex" union in struct
ib_send_wr. The invalidate_rkey member can be used to pass in an
R_Key/STag to be invalidated.  Add this new union to struct
ib_uverbs_send_wr.  Add code to copy the invalidate_rkey field in
ib_uverbs_post_send().

Fix up low-level drivers to deal with the change to struct ib_send_wr,
and just remove the imm_data initialization from net/sunrpc/xprtrdma/,
since that code never does any send with immediate operations.

Also, move the existing IB_DEVICE_SEND_W_INV flag to a new bit, since
the iWARP drivers currently in the tree set the bit.  The amso1100
driver at least will silently fail to honor the IB_SEND_INVALIDATE bit
if passed in as part of userspace send requests (since it does not
implement kernel bypass work request queueing).  Remove the flag from
all existing drivers that set it until we know which ones are OK.

The values chosen for the new flag is not consecutive to avoid clashing
with flags defined in the XRC patches, which are not merged yet but
which are already in use and are likely to be merged soon.

This resurrects a patch sent long ago by Mikkel Hagen <mhagen@iol.unh.edu>.

Signed-off-by: Roland Dreier <rolandd@cisco.com>
2008-04-16 21:09:32 -07:00
Tom Tucker
c8237a5fce SVCRDMA: Check num_sge when setting LAST_CTXT bit
The RDMACTXT_F_LAST_CTXT bit was getting set incorrectly
when the last chunk in the read-list spanned multiple pages. This
resulted in a kernel panic when the wrong context was used to
build the RPC iovec page list.

RDMA_READ is used to fetch RPC data from the client for
NFS_WRITE requests. A scatter-gather is used to map the
advertised client side buffer to the server-side iovec and
associated page list.

WR contexts are used to convey which scatter-gather entries are
handled by each WR. When the write data is large, a single RPC may
require multiple RDMA_READ requests so the contexts for a single RPC
are chained together in a linked list. The last context in this list
is marked with a bit RDMACTXT_F_LAST_CTXT so that when this WR completes,
the CQ handler code can enqueue the RPC for processing.

The code in rdma_read_xdr was setting this bit on the last two
contexts on this list when the last read-list chunk spanned multiple
pages. This caused the svc_rdma_recvfrom logic to incorrectly build
the RPC and caused the kernel to crash because the second-to-last
context doesn't contain the iovec page list.

Modified the condition that sets this bit so that it correctly detects
the last context for the RPC.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Tested-by: Roland Dreier <rolandd@cisco.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-03-26 11:24:19 -07:00