CIFS: Separate page processing from writepages

Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org>
Reviewed-by: Jeff Layton <jlayton@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 82 insertions, 70 deletions

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 6b6df30cfd89..69d176396d04 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1878,6 +1878,86 @@ static int cifs_partialpagewrite(struct page *page, unsigned from, unsigned to)
         return rc;
 }
 
+static unsigned int
+wdata_prepare_pages(struct cifs_writedata *wdata, unsigned int found_pages,
+                    struct address_space *mapping,
+                    struct writeback_control *wbc,
+                    pgoff_t end, pgoff_t *index, pgoff_t *next, bool *done)
+{
+        unsigned int nr_pages = 0, i;
+        struct page *page;
+
+        for (i = 0; i < found_pages; i++) {
+                page = wdata->pages[i];
+                /*
+                 * At this point we hold neither mapping->tree_lock nor
+                 * lock on the page itself: the page may be truncated or
+                 * invalidated (changing page->mapping to NULL), or even
+                 * swizzled back from swapper_space to tmpfs file
+                 * mapping
+                 */
+
+                if (nr_pages == 0)
+                        lock_page(page);
+                else if (!trylock_page(page))
+                        break;
+
+                if (unlikely(page->mapping != mapping)) {
+                        unlock_page(page);
+                        break;
+                }
+
+                if (!wbc->range_cyclic && page->index > end) {
+                        *done = true;
+                        unlock_page(page);
+                        break;
+                }
+
+                if (*next && (page->index != *next)) {
+                        /* Not next consecutive page */
+                        unlock_page(page);
+                        break;
+                }
+
+                if (wbc->sync_mode != WB_SYNC_NONE)
+                        wait_on_page_writeback(page);
+
+                if (PageWriteback(page) ||
+                                !clear_page_dirty_for_io(page)) {
+                        unlock_page(page);
+                        break;
+                }
+
+                /*
+                 * This actually clears the dirty bit in the radix tree.
+                 * See cifs_writepage() for more commentary.
+                 */
+                set_page_writeback(page);
+                if (page_offset(page) >= i_size_read(mapping->host)) {
+                        *done = true;
+                        unlock_page(page);
+                        end_page_writeback(page);
+                        break;
+                }
+
+                wdata->pages[i] = page;
+                *next = page->index + 1;
+                ++nr_pages;
+        }
+
+        /* reset index to refind any pages skipped */
+        if (nr_pages == 0)
+                *index = wdata->pages[0]->index + 1;
+
+        /* put any pages we aren't going to use */
+        for (i = nr_pages; i < found_pages; i++) {
+                page_cache_release(wdata->pages[i]);
+                wdata->pages[i] = NULL;
+        }
+
+        return nr_pages;
+}
+
 static int cifs_writepages(struct address_space *mapping,
                            struct writeback_control *wbc)
 {
@@ -1886,7 +1966,6 @@ static int cifs_writepages(struct address_space *mapping,
         pgoff_t end, index;
         struct cifs_writedata *wdata;
         struct TCP_Server_Info *server;
-        struct page *page;
         int rc = 0;
 
         /*
@@ -1944,75 +2023,8 @@ retry:
                         break;
                 }
 
-                nr_pages = 0;
-                for (i = 0; i < found_pages; i++) {
-                        page = wdata->pages[i];
-                        /*
-                         * At this point we hold neither mapping->tree_lock nor
-                         * lock on the page itself: the page may be truncated or
-                         * invalidated (changing page->mapping to NULL), or even
-                         * swizzled back from swapper_space to tmpfs file
-                         * mapping
-                         */
-
-                        if (nr_pages == 0)
-                                lock_page(page);
-                        else if (!trylock_page(page))
-                                break;
-
-                        if (unlikely(page->mapping != mapping)) {
-                                unlock_page(page);
-                                break;
-                        }
-
-                        if (!wbc->range_cyclic && page->index > end) {
-                                done = true;
-                                unlock_page(page);
-                                break;
-                        }
-
-                        if (next && (page->index != next)) {
-                                /* Not next consecutive page */
-                                unlock_page(page);
-                                break;
-                        }
-
-                        if (wbc->sync_mode != WB_SYNC_NONE)
-                                wait_on_page_writeback(page);
-
-                        if (PageWriteback(page) ||
-                                        !clear_page_dirty_for_io(page)) {
-                                unlock_page(page);
-                                break;
-                        }
-
-                        /*
-                         * This actually clears the dirty bit in the radix tree.
-                         * See cifs_writepage() for more commentary.
-                         */
-                        set_page_writeback(page);
-
-                        if (page_offset(page) >= i_size_read(mapping->host)) {
-                                done = true;
-                                unlock_page(page);
-                                end_page_writeback(page);
-                                break;
-                        }
-
-                        wdata->pages[i] = page;
-                        next = page->index + 1;
-                        ++nr_pages;
-                }
-
-                /* reset index to refind any pages skipped */
-                if (nr_pages == 0)
-                        index = wdata->pages[0]->index + 1;
-
-                /* put any pages we aren't going to use */
-                for (i = nr_pages; i < found_pages; i++) {
-                        page_cache_release(wdata->pages[i]);
-                        wdata->pages[i] = NULL;
-                }
+                nr_pages = wdata_prepare_pages(wdata, found_pages, mapping, wbc,
+                                               end, &index, &next, &done);
 
                 /* nothing to write? */
                 if (nr_pages == 0) {