From 5fe6eaa1f9a00b9a5927e3b791ecad2f3eaab130 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Thu, 15 Sep 2016 10:55:20 -0400 Subject: SUNRPC: Generalize the RPC buffer allocation API 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 Signed-off-by: Anna Schumaker --- net/sunrpc/sched.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) (limited to 'net/sunrpc/sched.c') diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index 9ae5885..b964d40 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -849,14 +849,17 @@ static void rpc_async_schedule(struct work_struct *work) } /** - * rpc_malloc - allocate an RPC buffer - * @task: RPC task that will use this buffer - * @size: requested byte size + * rpc_malloc - allocate RPC buffer resources + * @task: RPC task + * + * A single memory region is allocated, which is split between the + * RPC call and RPC reply that this task is being used for. When + * this RPC is retired, the memory is released by calling rpc_free. * * To prevent rpciod from hanging, this allocator never sleeps, - * returning NULL and suppressing warning if the request cannot be serviced - * immediately. - * The caller can arrange to sleep in a way that is safe for rpciod. + * returning -ENOMEM and suppressing warning if the request cannot + * be serviced immediately. The caller can arrange to sleep in a + * way that is safe for rpciod. * * Most requests are 'small' (under 2KiB) and can be serviced from a * mempool, ensuring that NFS reads and writes can always proceed, @@ -865,8 +868,10 @@ static void rpc_async_schedule(struct work_struct *work) * In order to avoid memory starvation triggering more writebacks of * NFS requests, we avoid using GFP_KERNEL. */ -void *rpc_malloc(struct rpc_task *task, size_t size) +int rpc_malloc(struct rpc_task *task) { + struct rpc_rqst *rqst = task->tk_rqstp; + size_t size = rqst->rq_callsize + rqst->rq_rcvsize; struct rpc_buffer *buf; gfp_t gfp = GFP_NOIO | __GFP_NOWARN; @@ -880,12 +885,13 @@ void *rpc_malloc(struct rpc_task *task, size_t size) buf = kmalloc(size, gfp); if (!buf) - return NULL; + return -ENOMEM; buf->len = size; dprintk("RPC: %5u allocated buffer of size %zu at %p\n", task->tk_pid, size, buf); - return &buf->data; + rqst->rq_buffer = buf->data; + return 0; } EXPORT_SYMBOL_GPL(rpc_malloc); -- cgit v1.1