Merge git://git.linux-nfs.org/pub/linux/nfs-2.6

* git://git.linux-nfs.org/pub/linux/nfs-2.6: (28 commits)
  NFS: Fix a compile glitch on 64-bit systems
  NFS: Clean up nfs_create_request comments
  spkm3: initialize hash
  spkm3: remove bad kfree, unnecessary export
  spkm3: fix spkm3's use of hmac
  NFS4: invalidate cached acl on setacl
  NFS: Fix directory caching problem - with test case and patch.
  NFS: Set meaningful value for fattr->time_start in readdirplus results.
  NFS: Added support to turn off the NFSv3 READDIRPLUS RPC.
  SUNRPC: RPC client should retry with different versions of rpcbind
  SUNRPC: remove old portmapper
  NFS: switch NFSROOT to use new rpcbind client
  SUNRPC: switch the RPC server to use the new rpcbind registration API
  SUNRPC: switch socket-based RPC transports to use rpcbind
  SUNRPC: introduce rpcbind: replacement for in-kernel portmapper
  SUNRPC: Eliminate side effects from rpc_malloc
  SUNRPC: RPC buffer size estimates are too large
  NLM: Shrink the maximum request size of NLM4 requests
  NFS: Use pgoff_t in structures and functions that pass page cache offsets
  NFS: Clean up nfs_sync_mapping_wait()
  ...

1 files changed, 34 insertions, 31 deletions

diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index 6d87320074b..4a53e94f813 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -741,50 +741,53 @@ static void rpc_async_schedule(struct work_struct *work)
  * @task: RPC task that will use this buffer
  * @size: requested byte size
  *
- * We try to ensure that some NFS reads and writes can always proceed
- * by using a mempool when allocating 'small' buffers.
+ * To prevent rpciod from hanging, this allocator never sleeps,
+ * returning NULL 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,
+ * and that there is good locality of reference for these buffers.
+ *
  * In order to avoid memory starvation triggering more writebacks of
- * NFS requests, we use GFP_NOFS rather than GFP_KERNEL.
+ * NFS requests, we avoid using GFP_KERNEL.
  */
-void * rpc_malloc(struct rpc_task *task, size_t size)
+void *rpc_malloc(struct rpc_task *task, size_t size)
 {
-	struct rpc_rqst *req = task->tk_rqstp;
-	gfp_t	gfp;
+	size_t *buf;
+	gfp_t gfp = RPC_IS_SWAPPER(task) ? GFP_ATOMIC : GFP_NOWAIT;
 
-	if (task->tk_flags & RPC_TASK_SWAPPER)
-		gfp = GFP_ATOMIC;
+	size += sizeof(size_t);
+	if (size <= RPC_BUFFER_MAXSIZE)
+		buf = mempool_alloc(rpc_buffer_mempool, gfp);
 	else
-		gfp = GFP_NOFS;
-
-	if (size > RPC_BUFFER_MAXSIZE) {
-		req->rq_buffer = kmalloc(size, gfp);
-		if (req->rq_buffer)
-			req->rq_bufsize = size;
-	} else {
-		req->rq_buffer = mempool_alloc(rpc_buffer_mempool, gfp);
-		if (req->rq_buffer)
-			req->rq_bufsize = RPC_BUFFER_MAXSIZE;
-	}
-	return req->rq_buffer;
+		buf = kmalloc(size, gfp);
+	*buf = size;
+	dprintk("RPC: %5u allocated buffer of size %u at %p\n",
+			task->tk_pid, size, buf);
+	return (void *) ++buf;
 }
 
 /**
  * rpc_free - free buffer allocated via rpc_malloc
- * @task: RPC task with a buffer to be freed
+ * @buffer: buffer to free
  *
  */
-void rpc_free(struct rpc_task *task)
+void rpc_free(void *buffer)
 {
-	struct rpc_rqst *req = task->tk_rqstp;
+	size_t size, *buf = (size_t *) buffer;
 
-	if (req->rq_buffer) {
-		if (req->rq_bufsize == RPC_BUFFER_MAXSIZE)
-			mempool_free(req->rq_buffer, rpc_buffer_mempool);
-		else
-			kfree(req->rq_buffer);
-		req->rq_buffer = NULL;
-		req->rq_bufsize = 0;
-	}
+	if (!buffer)
+		return;
+	size = *buf;
+	buf--;
+
+	dprintk("RPC:       freeing buffer of size %u at %p\n",
+			size, buf);
+	if (size <= RPC_BUFFER_MAXSIZE)
+		mempool_free(buf, rpc_buffer_mempool);
+	else
+		kfree(buf);
 }
 
 /*