[PATCH] Fix writeback page range to use exact limits

wait_on_page_writeback_range shouldn't wait for pages beyond the specified
range.  Ideally, the radix-tree-lookup could accept an end_index parameter so
that it doesn't return the extra pages in the first place, but for now we just
add a few extra checks to skip such pages.

Signed-off-by: Suparna Bhattacharya <suparna@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/mm/filemap.c b/mm/filemap.c
index a29efae1832c8c29ffd8089b4e73052333afe58a..912afa1bdc1536a8afdb03c5740736dfb4ac556d 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -198,7 +198,8 @@ static int wait_on_page_writeback_range(struct address_space *mapping,
 
        pagevec_init(&pvec, 0);
        index = start;
-       while ((nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
+       while ((index <= end) &&
+                       (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
                        PAGECACHE_TAG_WRITEBACK,
                        min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
                unsigned i;
@@ -206,6 +207,10 @@ static int wait_on_page_writeback_range(struct address_space *mapping,
                for (i = 0; i < nr_pages; i++) {
                        struct page *page = pvec.pages[i];
 
+                       /* until radix tree lookup accepts end_index */
+                       if (page->index > end)
+                               continue;
+
                        wait_on_page_writeback(page);
                        if (PageError(page))
                                ret = -EIO;