SUNRPC: Add a label for RPC calls that require allocation on receive

If the RPC call relies on the receive call allocating pages as buffers,
then let's label it so that we
a) Don't leak memory by allocating pages for requests that do not expect
   this behaviour
b) Can optimise for the common case where calls do not require allocation.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

diff --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c
index 64e4fa3..d8c4c10 100644 (file)
--- a/fs/nfs/nfs3xdr.c
+++ b/fs/nfs/nfs3xdr.c
@@ -1364,10 +1364,12 @@ static void nfs3_xdr_enc_getacl3args(struct rpc_rqst *req,
 
        encode_nfs_fh3(xdr, args->fh);
        encode_uint32(xdr, args->mask);
-       if (args->mask & (NFS_ACL | NFS_DFACL))
+       if (args->mask & (NFS_ACL | NFS_DFACL)) {
                prepare_reply_buffer(req, args->pages, 0,
                                        NFSACL_MAXPAGES << PAGE_SHIFT,
                                        ACL3_getaclres_sz);
+               req->rq_rcv_buf.flags |= XDRBUF_SPARSE_PAGES;
+       }
 }
 
 static void nfs3_xdr_enc_setacl3args(struct rpc_rqst *req,

diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
index 2bd6817..4318292 100644 (file)
--- a/include/linux/sunrpc/xdr.h
+++ b/include/linux/sunrpc/xdr.h
@@ -58,6 +58,7 @@ struct xdr_buf {
                        flags;          /* Flags for data disposition */
 #define XDRBUF_READ            0x01            /* target of file read */
 #define XDRBUF_WRITE           0x02            /* source of file write */
+#define XDRBUF_SPARSE_PAGES    0x04            /* Page array is sparse */
 
        unsigned int    buflen,         /* Total length of storage buffer */
                        len;            /* Length of XDR encoded message */

diff --git a/net/sunrpc/auth_gss/gss_rpc_xdr.c b/net/sunrpc/auth_gss/gss_rpc_xdr.c
index 444380f..006062a 100644 (file)
--- a/net/sunrpc/auth_gss/gss_rpc_xdr.c
+++ b/net/sunrpc/auth_gss/gss_rpc_xdr.c
@@ -784,6 +784,7 @@ void gssx_enc_accept_sec_context(struct rpc_rqst *req,
        xdr_inline_pages(&req->rq_rcv_buf,
                PAGE_SIZE/2 /* pretty arbitrary */,
                arg->pages, 0 /* page base */, arg->npages * PAGE_SIZE);
+       req->rq_rcv_buf.flags |= XDRBUF_SPARSE_PAGES;
 done:
        if (err)
                dprintk("RPC:       gssx_enc_accept_sec_context: %d\n", err);

diff --git a/net/sunrpc/socklib.c b/net/sunrpc/socklib.c
index f217c34..08f00a9 100644 (file)
--- a/net/sunrpc/socklib.c
+++ b/net/sunrpc/socklib.c
@@ -104,7 +104,7 @@ ssize_t xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, struct
 
                /* ACL likes to be lazy in allocating pages - ACLs
                 * are small by default but can get huge. */
-               if (unlikely(*ppage == NULL)) {
+               if ((xdr->flags & XDRBUF_SPARSE_PAGES) && *ppage == NULL) {
                        *ppage = alloc_page(GFP_ATOMIC);
                        if (unlikely(*ppage == NULL)) {
                                if (copied == 0)