CIFS: Separate pages initialization from writepages

Reviewed-by: Shirish Pargaonkar <spargaonkar@suse.com>
Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>

fs/cifs/file.c

@@ -1878,6 +1878,40 @@ static int cifs_partialpagewrite(struct page *page, unsigned from, unsigned to)
 	return rc;
 }
 
+static struct cifs_writedata *
+wdata_alloc_and_fillpages(pgoff_t tofind, struct address_space *mapping,
+			  pgoff_t end, pgoff_t *index,
+			  unsigned int *found_pages)
+{
+	unsigned int nr_pages;
+	struct page **pages;
+	struct cifs_writedata *wdata;
+
+	wdata = cifs_writedata_alloc((unsigned int)tofind,
+				     cifs_writev_complete);
+	if (!wdata)
+		return NULL;
+
+	/*
+	 * find_get_pages_tag seems to return a max of 256 on each
+	 * iteration, so we must call it several times in order to
+	 * fill the array or the wsize is effectively limited to
+	 * 256 * PAGE_CACHE_SIZE.
+	 */
+	*found_pages = 0;
+	pages = wdata->pages;
+	do {
+		nr_pages = find_get_pages_tag(mapping, index,
+					      PAGECACHE_TAG_DIRTY, tofind,
+					      pages);
+		*found_pages += nr_pages;
+		tofind -= nr_pages;
+		pages += nr_pages;
+	} while (nr_pages && tofind && *index <= end);
+
+	return wdata;
+}
+
 static unsigned int
 wdata_prepare_pages(struct cifs_writedata *wdata, unsigned int found_pages,
 		    struct address_space *mapping,
@@ -2025,35 +2059,17 @@ retry:
 	while (!done && index <= end) {
 		unsigned int i, nr_pages, found_pages;
 		pgoff_t next = 0, tofind;
-		struct page **pages;
 
 		tofind = min((cifs_sb->wsize / PAGE_CACHE_SIZE) - 1,
 				end - index) + 1;
 
-		wdata = cifs_writedata_alloc((unsigned int)tofind,
-					     cifs_writev_complete);
+		wdata = wdata_alloc_and_fillpages(tofind, mapping, end, &index,
+						  &found_pages);
 		if (!wdata) {
 			rc = -ENOMEM;
 			break;
 		}
 
-		/*
-		 * find_get_pages_tag seems to return a max of 256 on each
-		 * iteration, so we must call it several times in order to
-		 * fill the array or the wsize is effectively limited to
-		 * 256 * PAGE_CACHE_SIZE.
-		 */
-		found_pages = 0;
-		pages = wdata->pages;
-		do {
-			nr_pages = find_get_pages_tag(mapping, &index,
-							PAGECACHE_TAG_DIRTY,
-							tofind, pages);
-			found_pages += nr_pages;
-			tofind -= nr_pages;
-			pages += nr_pages;
-		} while (nr_pages && tofind && index <= end);
-
 		if (found_pages == 0) {
 			kref_put(&wdata->refcount, cifs_writedata_release);
 			break;