[PATCH] RPC: Lazy RPC receive buffer allocation

 Signed-off-by: Olaf Kirch <okir@suse.de>
 Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

3 files changed, 36 insertions, 8 deletions

diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
index 541dcf838abf..0f5b7a5a7432 100644
--- a/include/linux/sunrpc/xdr.h
+++ b/include/linux/sunrpc/xdr.h
@@ -160,7 +160,7 @@ typedef struct {
 
 typedef size_t (*skb_read_actor_t)(skb_reader_t *desc, void *to, size_t len);
 
-extern void xdr_partial_copy_from_skb(struct xdr_buf *, unsigned int,
+extern int xdr_partial_copy_from_skb(struct xdr_buf *, unsigned int,
                 skb_reader_t *, skb_read_actor_t);
 
 struct socket;
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index f86d1baa6302..65b268d39782 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -176,7 +176,7 @@ xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
         xdr->buflen += len;
 }
 
-void
+int
 xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base,
                           skb_reader_t *desc,
                           skb_read_actor_t copy_actor)
@@ -190,7 +190,7 @@ xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base,
                 len -= base;
                 ret = copy_actor(desc, (char *)xdr->head[0].iov_base + base, len);
                 if (ret != len || !desc->count)
-                        return;
+                        return 0;
                 base = 0;
         } else
                 base -= len;
@@ -210,6 +210,14 @@ xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base,
         do {
                 char *kaddr;
 
+                /* ACL likes to be lazy in allocating pages - ACLs
+                 * are small by default but can get huge. */
+                if (unlikely(*ppage == NULL)) {
+                        *ppage = alloc_page(GFP_ATOMIC);
+                        if (unlikely(*ppage == NULL))
+                                return -ENOMEM;
+                }
+
                 len = PAGE_CACHE_SIZE;
                 kaddr = kmap_atomic(*ppage, KM_SKB_SUNRPC_DATA);
                 if (base) {
@@ -226,13 +234,15 @@ xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base,
                 flush_dcache_page(*ppage);
                 kunmap_atomic(kaddr, KM_SKB_SUNRPC_DATA);
                 if (ret != len || !desc->count)
-                        return;
+                        return 0;
                 ppage++;
         } while ((pglen -= len) != 0);
 copy_tail:
         len = xdr->tail[0].iov_len;
         if (base < len)
                 copy_actor(desc, (char *)xdr->tail[0].iov_base + base, len - base);
+
+        return 0;
 }
 
 
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index c74a6bb94074..a180ed4952d6 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -725,7 +725,8 @@ csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
                 goto no_checksum;
 
         desc.csum = csum_partial(skb->data, desc.offset, skb->csum);
-        xdr_partial_copy_from_skb(xdr, 0, &desc, skb_read_and_csum_bits);
+        if (xdr_partial_copy_from_skb(xdr, 0, &desc, skb_read_and_csum_bits) < 0)
+                return -1;
         if (desc.offset != skb->len) {
                 unsigned int csum2;
                 csum2 = skb_checksum(skb, desc.offset, skb->len - desc.offset, 0);
@@ -737,7 +738,8 @@ csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
                 return -1;
         return 0;
 no_checksum:
-        xdr_partial_copy_from_skb(xdr, 0, &desc, skb_read_bits);
+        if (xdr_partial_copy_from_skb(xdr, 0, &desc, skb_read_bits) < 0)
+                return -1;
         if (desc.count)
                 return -1;
         return 0;
@@ -907,6 +909,7 @@ tcp_read_request(struct rpc_xprt *xprt, skb_reader_t *desc)
         struct rpc_rqst *req;
         struct xdr_buf *rcvbuf;
         size_t len;
+        int r;
 
         /* Find and lock the request corresponding to this xid */
         spin_lock(&xprt->sock_lock);
@@ -927,16 +930,30 @@ tcp_read_request(struct rpc_xprt *xprt, skb_reader_t *desc)
                 len = xprt->tcp_reclen - xprt->tcp_offset;
                 memcpy(&my_desc, desc, sizeof(my_desc));
                 my_desc.count = len;
-                xdr_partial_copy_from_skb(rcvbuf, xprt->tcp_copied,
+                r = xdr_partial_copy_from_skb(rcvbuf, xprt->tcp_copied,
                                           &my_desc, tcp_copy_data);
                 desc->count -= len;
                 desc->offset += len;
         } else
-                xdr_partial_copy_from_skb(rcvbuf, xprt->tcp_copied,
+                r = xdr_partial_copy_from_skb(rcvbuf, xprt->tcp_copied,
                                           desc, tcp_copy_data);
         xprt->tcp_copied += len;
         xprt->tcp_offset += len;
 
+        if (r < 0) {
+                /* Error when copying to the receive buffer,
+                 * usually because we weren't able to allocate
+                 * additional buffer pages. All we can do now
+                 * is turn off XPRT_COPY_DATA, so the request
+                 * will not receive any additional updates,
+                 * and time out.
+                 * Any remaining data from this record will
+                 * be discarded.
+                 */
+                xprt->tcp_flags &= ~XPRT_COPY_DATA;
+                goto out;
+        }
+
         if (xprt->tcp_copied == req->rq_private_buf.buflen)
                 xprt->tcp_flags &= ~XPRT_COPY_DATA;
         else if (xprt->tcp_offset == xprt->tcp_reclen) {
@@ -949,6 +966,7 @@ tcp_read_request(struct rpc_xprt *xprt, skb_reader_t *desc)
                                 req->rq_task->tk_pid);
                 xprt_complete_rqst(xprt, req, xprt->tcp_copied);
         }
+out:
         spin_unlock(&xprt->sock_lock);
         tcp_check_recm(xprt);
 }