ext4: Use tag dirty lookup during mpage_da_submit_io

commit af6f029d3836eb7264cd3fbb13a6baf0e5fdb5ea upstream.

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>
Signed-off-by: Jayson R. King <dev@jaysonking.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 71901ae7e05acab1febc9e5512db86383b7b78f9..a67f8374ac3af0fac90bf00c55ff16f3a12bb877 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1699,17 +1699,23 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd)
 
        pagevec_init(&pvec, 0);
        while (index <= end) {
-               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++;
-
                        BUG_ON(!PageLocked(page));
                        BUG_ON(PageWriteback(page));
 
@@ -2442,7 +2448,6 @@ 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;
@@ -2481,14 +2486,7 @@ 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;
@@ -2559,9 +2557,8 @@ 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;
@@ -2570,7 +2567,6 @@ restart_loop:
 
 out_writepages:
        wbc->nr_to_write = to_write - nr_to_writebump;
-       wbc->range_start = range_start;
        return ret;
 }