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SUNRPC: Generalize the RPC buffer allocation API

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xprtrdma needs to allocate the Call and Reply buffers separately.
TBH, the reliance on using a single buffer for the pair of XDR
buffers is transport implementation-specific.

Transports that want to allocate separate Call and Reply buffers
will ignore the "size" argument anyway.  Don't bother passing it.

The buf_alloc method can't return two pointers. Instead, make the
method's return value an error code, and set the rq_buffer pointer
in the method itself.

This gives call_allocate an opportunity to terminate an RPC instead
of looping forever when a permanent problem occurs. If a request is
just bogus, or the transport is in a state where it can't allocate
resources for any request, there needs to be a way to kill the RPC
right there and not loop.

This immediately fixes a rare problem in the backchannel send path,
which loops if the server happens to send a CB request whose
call+reply size is larger than a page (which it shouldn't do yet).

One more issue: looks like xprt_inject_disconnect was incorrectly
placed in the failure path in call_allocate. It needs to be in the
success path, as it is for other call-sites.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Chuck Lever
2016-09-15 10:55:20 -04:00
committed by Anna Schumaker
parent b9c5bc03be
commit 5fe6eaa1f9
7 changed files with 63 additions and 37 deletions
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17
net/sunrpc/xprtrdma/svc_rdma_backchannel.c
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@@ -159,29 +159,30 @@ out_unmap:
/* Server-side transport endpoint wants a whole page for its send
* buffer. The client RPC code constructs the RPC header in this
* buffer before it invokes ->send_request.
*
* Returns NULL if there was a temporary allocation failure.
*/
static void *
xprt_rdma_bc_allocate(struct rpc_task *task, size_t size)
static int
xprt_rdma_bc_allocate(struct rpc_task *task)
{
struct rpc_rqst *rqst = task->tk_rqstp;
struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
size_t size = rqst->rq_callsize;
struct svcxprt_rdma *rdma;
struct page *page;
rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt);
/* Prevent an infinite loop: try to make this case work */
if (size > PAGE_SIZE)
if (size > PAGE_SIZE) {
WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
size);
return -EINVAL;
}
page = alloc_page(RPCRDMA_DEF_GFP);
if (!page)
return NULL;
return -ENOMEM;
return page_address(page);
rqst->rq_buffer = page_address(page);
return 0;
}
static void