afs: Use a bvec rather than a kvec in afs_send_pages()

Use a bvec rather than a kvec in afs_send_pages() as we don't then have to
call kmap() in advance.  This allows us to pass the array of contiguous
pages that we extracted through to rxrpc in one go rather than passing a
single page at a time.

Signed-off-by: David Howells <dhowells@redhat.com>

diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index 419ef05..bf45307 100644 (file)
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -259,67 +259,74 @@ void afs_flat_call_destructor(struct afs_call *call)
        call->buffer = NULL;
 }
 
+#define AFS_BVEC_MAX 8
+
+/*
+ * Load the given bvec with the next few pages.
+ */
+static void afs_load_bvec(struct afs_call *call, struct msghdr *msg,
+                         struct bio_vec *bv, pgoff_t first, pgoff_t last,
+                         unsigned offset)
+{
+       struct page *pages[AFS_BVEC_MAX];
+       unsigned int nr, n, i, to, bytes = 0;
+
+       nr = min_t(pgoff_t, last - first + 1, AFS_BVEC_MAX);
+       n = find_get_pages_contig(call->mapping, first, nr, pages);
+       ASSERTCMP(n, ==, nr);
+
+       msg->msg_flags |= MSG_MORE;
+       for (i = 0; i < nr; i++) {
+               to = PAGE_SIZE;
+               if (first + i >= last) {
+                       to = call->last_to;
+                       msg->msg_flags &= ~MSG_MORE;
+               }
+               bv[i].bv_page = pages[i];
+               bv[i].bv_len = to - offset;
+               bv[i].bv_offset = offset;
+               bytes += to - offset;
+               offset = 0;
+       }
+
+       iov_iter_bvec(&msg->msg_iter, WRITE | ITER_BVEC, bv, nr, bytes);
+}
+
 /*
  * attach the data from a bunch of pages on an inode to a call
  */
 static int afs_send_pages(struct afs_call *call, struct msghdr *msg)
 {
-       struct page *pages[8];
-       unsigned count, n, loop, offset, to;
+       struct bio_vec bv[AFS_BVEC_MAX];
+       unsigned int bytes, nr, loop, offset;
        pgoff_t first = call->first, last = call->last;
        int ret;
 
-       _enter("");
-
        offset = call->first_offset;
        call->first_offset = 0;
 
        do {
-               _debug("attach %lx-%lx", first, last);
-
-               count = last - first + 1;
-               if (count > ARRAY_SIZE(pages))
-                       count = ARRAY_SIZE(pages);
-               n = find_get_pages_contig(call->mapping, first, count, pages);
-               ASSERTCMP(n, ==, count);
-
-               loop = 0;
-               do {
-                       struct bio_vec bvec = {.bv_page = pages[loop],
-                                              .bv_offset = offset};
-                       msg->msg_flags = 0;
-                       to = PAGE_SIZE;
-                       if (first + loop >= last)
-                               to = call->last_to;
-                       else
-                               msg->msg_flags = MSG_MORE;
-                       bvec.bv_len = to - offset;
-                       offset = 0;
-
-                       _debug("- range %u-%u%s",
-                              offset, to, msg->msg_flags ? " [more]" : "");
-                       iov_iter_bvec(&msg->msg_iter, WRITE | ITER_BVEC,
-                                     &bvec, 1, to - offset);
-
-                       /* have to change the state *before* sending the last
-                        * packet as RxRPC might give us the reply before it
-                        * returns from sending the request */
-                       if (first + loop >= last)
-                               call->state = AFS_CALL_AWAIT_REPLY;
-                       ret = rxrpc_kernel_send_data(afs_socket, call->rxcall,
-                                                    msg, to - offset);
-                       if (ret < 0)
-                               break;
-               } while (++loop < count);
-               first += count;
-
-               for (loop = 0; loop < count; loop++)
-                       put_page(pages[loop]);
+               afs_load_bvec(call, msg, bv, first, last, offset);
+               offset = 0;
+               bytes = msg->msg_iter.count;
+               nr = msg->msg_iter.nr_segs;
+
+               /* Have to change the state *before* sending the last
+                * packet as RxRPC might give us the reply before it
+                * returns from sending the request.
+                */
+               if (first + nr >= last)
+                       call->state = AFS_CALL_AWAIT_REPLY;
+               ret = rxrpc_kernel_send_data(afs_socket, call->rxcall,
+                                            msg, bytes);
+               for (loop = 0; loop < nr; loop++)
+                       put_page(bv[loop].bv_page);
                if (ret < 0)
                        break;
+
+               first += nr;
        } while (first <= last);
 
-       _leave(" = %d", ret);
        return ret;
 }