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 <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

View File

@ -239,7 +239,7 @@ struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *,
void *);
void rpc_wake_up_status(struct rpc_wait_queue *, int);
void rpc_delay(struct rpc_task *, unsigned long);
void * rpc_malloc(struct rpc_task *, size_t);
int rpc_malloc(struct rpc_task *);
void rpc_free(void *);
int rpciod_up(void);
void rpciod_down(void);

View File

@ -127,7 +127,7 @@ struct rpc_xprt_ops {
void (*rpcbind)(struct rpc_task *task);
void (*set_port)(struct rpc_xprt *xprt, unsigned short port);
void (*connect)(struct rpc_xprt *xprt, struct rpc_task *task);
void * (*buf_alloc)(struct rpc_task *task, size_t size);
int (*buf_alloc)(struct rpc_task *task);
void (*buf_free)(void *buffer);
int (*send_request)(struct rpc_task *task);
void (*set_retrans_timeout)(struct rpc_task *task);

View File

@ -1691,6 +1691,7 @@ call_allocate(struct rpc_task *task)
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
struct rpc_procinfo *proc = task->tk_msg.rpc_proc;
int status;
dprint_status(task);
@ -1716,11 +1717,14 @@ call_allocate(struct rpc_task *task)
req->rq_rcvsize = RPC_REPHDRSIZE + slack + proc->p_replen;
req->rq_rcvsize <<= 2;
req->rq_buffer = xprt->ops->buf_alloc(task,
req->rq_callsize + req->rq_rcvsize);
if (req->rq_buffer != NULL)
return;
status = xprt->ops->buf_alloc(task);
xprt_inject_disconnect(xprt);
if (status == 0)
return;
if (status != -ENOMEM) {
rpc_exit(task, status);
return;
}
dprintk("RPC: %5u rpc_buffer allocation failed\n", task->tk_pid);

View File

@ -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);

View File

@ -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

View File

@ -477,7 +477,15 @@ xprt_rdma_connect(struct rpc_xprt *xprt, struct rpc_task *task)
}
}
/*
/**
* xprt_rdma_allocate - allocate transport resources for an RPC
* @task: RPC task
*
* Return values:
* 0: Success; rq_buffer points to RPC buffer to use
* ENOMEM: Out of memory, call again later
* EIO: A permanent error occurred, do not retry
*
* The RDMA allocate/free functions need the task structure as a place
* to hide the struct rpcrdma_req, which is necessary for the actual send/recv
* sequence.
@ -486,11 +494,12 @@ xprt_rdma_connect(struct rpc_xprt *xprt, struct rpc_task *task)
* (rq_send_buf and rq_rcv_buf are both part of a single contiguous buffer).
* We may register rq_rcv_buf when using reply chunks.
*/
static void *
xprt_rdma_allocate(struct rpc_task *task, size_t size)
static int
xprt_rdma_allocate(struct rpc_task *task)
{
struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
struct rpc_rqst *rqst = task->tk_rqstp;
size_t size = rqst->rq_callsize + rqst->rq_rcvsize;
struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(rqst->rq_xprt);
struct rpcrdma_regbuf *rb;
struct rpcrdma_req *req;
size_t min_size;
@ -498,7 +507,7 @@ xprt_rdma_allocate(struct rpc_task *task, size_t size)
req = rpcrdma_buffer_get(&r_xprt->rx_buf);
if (req == NULL)
return NULL;
return -ENOMEM;
flags = RPCRDMA_DEF_GFP;
if (RPC_IS_SWAPPER(task))
@ -515,7 +524,8 @@ out:
dprintk("RPC: %s: size %zd, request 0x%p\n", __func__, size, req);
req->rl_connect_cookie = 0; /* our reserved value */
req->rl_task = task;
return req->rl_sendbuf->rg_base;
rqst->rq_buffer = req->rl_sendbuf->rg_base;
return 0;
out_rdmabuf:
min_size = r_xprt->rx_data.inline_wsize;
@ -558,7 +568,7 @@ out_sendbuf:
out_fail:
rpcrdma_buffer_put(req);
return NULL;
return -ENOMEM;
}
/*

View File

@ -2533,23 +2533,28 @@ static void xs_tcp_print_stats(struct rpc_xprt *xprt, struct seq_file *seq)
* we allocate pages instead doing a kmalloc like rpc_malloc is because we want
* to use the server side send routines.
*/
static void *bc_malloc(struct rpc_task *task, size_t size)
static int bc_malloc(struct rpc_task *task)
{
struct rpc_rqst *rqst = task->tk_rqstp;
size_t size = rqst->rq_callsize;
struct page *page;
struct rpc_buffer *buf;
WARN_ON_ONCE(size > PAGE_SIZE - sizeof(struct rpc_buffer));
if (size > PAGE_SIZE - sizeof(struct rpc_buffer))
return NULL;
if (size > PAGE_SIZE - sizeof(struct rpc_buffer)) {
WARN_ONCE(1, "xprtsock: large bc buffer request (size %zu)\n",
size);
return -EINVAL;
}
page = alloc_page(GFP_KERNEL);
if (!page)
return NULL;
return -ENOMEM;
buf = page_address(page);
buf->len = PAGE_SIZE;
return buf->data;
rqst->rq_buffer = buf->data;
return 0;
}
/*