CIFS: Separate filling pages from iovec write

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

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index ff4a9c3fe4215468289f88b275eba80ad89aee57..f96f61c849fe2b34c14d1fe9bb347ac9049ed05a 100644 (file)
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2423,11 +2423,53 @@ cifs_uncached_retry_writev(struct cifs_writedata *wdata)
        return rc;
 }
 
+static int
+wdata_fill_from_iovec(struct cifs_writedata *wdata, struct iov_iter *from,
+                     size_t *len, unsigned long *num_pages)
+{
+       size_t save_len, copied, bytes, cur_len = *len;
+       unsigned long i, nr_pages = *num_pages;
+
+       save_len = cur_len;
+       for (i = 0; i < nr_pages; i++) {
+               bytes = min_t(const size_t, cur_len, PAGE_SIZE);
+               copied = copy_page_from_iter(wdata->pages[i], 0, bytes, from);
+               cur_len -= copied;
+               /*
+                * If we didn't copy as much as we expected, then that
+                * may mean we trod into an unmapped area. Stop copying
+                * at that point. On the next pass through the big
+                * loop, we'll likely end up getting a zero-length
+                * write and bailing out of it.
+                */
+               if (copied < bytes)
+                       break;
+       }
+       cur_len = save_len - cur_len;
+       *len = cur_len;
+
+       /*
+        * If we have no data to send, then that probably means that
+        * the copy above failed altogether. That's most likely because
+        * the address in the iovec was bogus. Return -EFAULT and let
+        * the caller free anything we allocated and bail out.
+        */
+       if (!cur_len)
+               return -EFAULT;
+
+       /*
+        * i + 1 now represents the number of pages we actually used in
+        * the copy phase above.
+        */
+       *num_pages = i + 1;
+       return 0;
+}
+
 static ssize_t
 cifs_iovec_write(struct file *file, struct iov_iter *from, loff_t *poffset)
 {
-       unsigned long nr_pages, i;
-       size_t bytes, copied, len, cur_len;
+       unsigned long nr_pages, num_pages, i;
+       size_t len, cur_len;
        ssize_t total_written = 0;
        loff_t offset;
        struct cifsFileInfo *open_file;
@@ -2464,8 +2506,6 @@ cifs_iovec_write(struct file *file, struct iov_iter *from, loff_t *poffset)
                pid = current->tgid;
 
        do {
-               size_t save_len;
-
                nr_pages = get_numpages(cifs_sb->wsize, len, &cur_len);
                wdata = cifs_writedata_alloc(nr_pages,
                                             cifs_uncached_writev_complete);
@@ -2480,44 +2520,20 @@ cifs_iovec_write(struct file *file, struct iov_iter *from, loff_t *poffset)
                        break;
                }
 
-               save_len = cur_len;
-               for (i = 0; i < nr_pages; i++) {
-                       bytes = min_t(size_t, cur_len, PAGE_SIZE);
-                       copied = copy_page_from_iter(wdata->pages[i], 0, bytes,
-                                                    from);
-                       cur_len -= copied;
-                       /*
-                        * If we didn't copy as much as we expected, then that
-                        * may mean we trod into an unmapped area. Stop copying
-                        * at that point. On the next pass through the big
-                        * loop, we'll likely end up getting a zero-length
-                        * write and bailing out of it.
-                        */
-                       if (copied < bytes)
-                               break;
-               }
-               cur_len = save_len - cur_len;
-
-               /*
-                * If we have no data to send, then that probably means that
-                * the copy above failed altogether. That's most likely because
-                * the address in the iovec was bogus. Set the rc to -EFAULT,
-                * free anything we allocated and bail out.
-                */
-               if (!cur_len) {
+               num_pages = nr_pages;
+               rc = wdata_fill_from_iovec(wdata, from, &cur_len, &num_pages);
+               if (rc) {
                        for (i = 0; i < nr_pages; i++)
                                put_page(wdata->pages[i]);
                        kfree(wdata);
-                       rc = -EFAULT;
                        break;
                }
 
                /*
-                * i + 1 now represents the number of pages we actually used in
-                * the copy phase above. Bring nr_pages down to that, and free
-                * any pages that we didn't use.
+                * Bring nr_pages down to the number of pages we actually used,
+                * and free any pages that we didn't use.
                 */
-               for ( ; nr_pages > i + 1; nr_pages--)
+               for ( ; nr_pages > num_pages; nr_pages--)
                        put_page(wdata->pages[nr_pages - 1]);
 
                wdata->sync_mode = WB_SYNC_ALL;