nfsd4: reorganize write decoding

In preparation for moving some of it elsewhere.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 41 insertions, 21 deletions

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index cfebc9c4f4c9..579dc707bad9 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -1139,12 +1139,30 @@ nfsd4_decode_verify(struct nfsd4_compoundargs *argp, struct nfsd4_verify *verify
         DECODE_TAIL;
 }
 
+static int fill_in_write_vector(struct kvec *vec, struct kvec *head, struct page **pagelist, int buflen)
+{
+        int i = 1;
+
+        vec[0].iov_base = head->iov_base;
+        vec[0].iov_len = min_t(int, buflen, head->iov_len);
+        buflen -= vec[0].iov_len;
+
+        while (buflen) {
+                vec[i].iov_base = page_address(pagelist[i - 1]);
+                vec[i].iov_len = min_t(int, PAGE_SIZE, buflen);
+                buflen -= vec[i].iov_len;
+                i++;
+        }
+        return i;
+}
+
 static __be32
 nfsd4_decode_write(struct nfsd4_compoundargs *argp, struct nfsd4_write *write)
 {
         int avail;
-        int v;
         int len;
+        struct page **pagelist;
+        struct kvec head;
         DECODE_HEAD;
 
         status = nfsd4_decode_stateid(argp, &write->wr_stateid);
@@ -1167,27 +1185,29 @@ nfsd4_decode_write(struct nfsd4_compoundargs *argp, struct nfsd4_write *write)
                                 __FILE__, __LINE__);
                 goto xdr_error;
         }
-        argp->rqstp->rq_vec[0].iov_base = p;
-        argp->rqstp->rq_vec[0].iov_len = avail;
-        v = 0;
-        len = write->wr_buflen;
-        while (len > argp->rqstp->rq_vec[v].iov_len) {
-                len -= argp->rqstp->rq_vec[v].iov_len;
-                v++;
-                argp->rqstp->rq_vec[v].iov_base = page_address(argp->pagelist[0]);
-                argp->pagelist++;
-                if (argp->pagelen >= PAGE_SIZE) {
-                        argp->rqstp->rq_vec[v].iov_len = PAGE_SIZE;
-                        argp->pagelen -= PAGE_SIZE;
-                } else {
-                        argp->rqstp->rq_vec[v].iov_len = argp->pagelen;
-                        argp->pagelen -= len;
-                }
+        head.iov_base = p;
+        head.iov_len = avail;
+        WARN_ON(avail != (XDR_QUADLEN(avail) << 2));
+        pagelist = argp->pagelist;
+
+        len = XDR_QUADLEN(write->wr_buflen) << 2;
+        if (len >= avail) {
+                int pages;
+
+                len -= avail;
+
+                pages = len >> PAGE_SHIFT;
+                argp->pagelist += pages;
+                argp->pagelen -= pages * PAGE_SIZE;
+                len -= pages * PAGE_SIZE;
+
+                argp->p = (__be32 *)page_address(argp->pagelist[0]);
+                argp->end = argp->p + XDR_QUADLEN(PAGE_SIZE);
         }
-        argp->end = (__be32*) (argp->rqstp->rq_vec[v].iov_base + argp->rqstp->rq_vec[v].iov_len);
-        argp->p = (__be32*)  (argp->rqstp->rq_vec[v].iov_base + (XDR_QUADLEN(len) << 2));
-        argp->rqstp->rq_vec[v].iov_len = len;
-        write->wr_vlen = v+1;
+        argp->p += XDR_QUADLEN(len);
+        write->wr_vlen = fill_in_write_vector(argp->rqstp->rq_vec,
+                &head, pagelist, write->wr_buflen);
+        WARN_ON_ONCE(write->wr_vlen > ARRAY_SIZE(argp->rqstp->rq_vec));
 
         DECODE_TAIL;
 }