ext4: Use tag dirty lookup during mpage_da_submit_io

This enables us to drop the range_cont writeback mode
use from ext4_da_writepages.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

1 files changed, 13 insertions, 17 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9b4ec9decfd1..4ee3f0692eeb 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1656,17 +1656,23 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd)
 
         while (index <= end) {
                 /* XXX: optimize tail */
-                nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
+                /*
+                 * We can use PAGECACHE_TAG_DIRTY lookup here because
+                 * even though we have cleared the dirty flag on the page
+                 * We still keep the page in the radix tree with tag
+                 * PAGECACHE_TAG_DIRTY. See clear_page_dirty_for_io.
+                 * The PAGECACHE_TAG_DIRTY is cleared in set_page_writeback
+                 * which is called via the below writepage callback.
+                 */
+                nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
+                                        PAGECACHE_TAG_DIRTY,
+                                        min(end - index,
+                                        (pgoff_t)PAGEVEC_SIZE-1) + 1);
                 if (nr_pages == 0)
                         break;
                 for (i = 0; i < nr_pages; i++) {
                         struct page *page = pvec.pages[i];
 
-                        index = page->index;
-                        if (index > end)
-                                break;
-                        index++;
-
                         err = mapping->a_ops->writepage(page, mpd->wbc);
                         if (!err)
                                 mpd->pages_written++;
@@ -2361,7 +2367,6 @@ static int ext4_da_writepages(struct address_space *mapping,
                               struct writeback_control *wbc)
 {
         handle_t *handle = NULL;
-        loff_t range_start = 0;
         struct mpage_da_data mpd;
         struct inode *inode = mapping->host;
         int needed_blocks, ret = 0, nr_to_writebump = 0;
@@ -2386,14 +2391,7 @@ static int ext4_da_writepages(struct address_space *mapping,
                 wbc->nr_to_write = sbi->s_mb_stream_request;
         }
 
-        if (!wbc->range_cyclic)
-                /*
-                 * If range_cyclic is not set force range_cont
-                 * and save the old writeback_index
-                 */
-                wbc->range_cont = 1;
 
-        range_start =  wbc->range_start;
         pages_skipped = wbc->pages_skipped;
 
         mpd.wbc = wbc;
@@ -2452,9 +2450,8 @@ restart_loop:
                 wbc->nr_to_write = to_write;
         }
 
-        if (wbc->range_cont && (pages_skipped != wbc->pages_skipped)) {
+        if (!wbc->range_cyclic && (pages_skipped != wbc->pages_skipped)) {
                 /* We skipped pages in this loop */
-                wbc->range_start = range_start;
                 wbc->nr_to_write = to_write +
                                 wbc->pages_skipped - pages_skipped;
                 wbc->pages_skipped = pages_skipped;
@@ -2463,7 +2460,6 @@ restart_loop:
 
 out_writepages:
         wbc->nr_to_write = to_write - nr_to_writebump;
-        wbc->range_start = range_start;
         return ret;
 }