[GFS2] Bug fix to gfs2_readpages()

This fixes a bug where we were releasing a page incorrectly
sometimes when reading a stuffed file. This fixes the bug
that Kevin reported when using Xen.

Cc: Kevin Anderson <kanderso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 5 insertions, 5 deletions

diff --git a/fs/gfs2/ops_address.c b/fs/gfs2/ops_address.c
index 27ce30148e69..2c4ec5cf21ff 100644
--- a/fs/gfs2/ops_address.c
+++ b/fs/gfs2/ops_address.c
@@ -249,8 +249,6 @@ out_unlock:
         goto out;
 }
 
-#define list_to_page(head) (list_entry((head)->prev, struct page, lru))
-
 /**
  * gfs2_readpages - Read a bunch of pages at once
  *
@@ -290,7 +288,8 @@ static int gfs2_readpages(struct file *file, struct address_space *mapping,
                 struct pagevec lru_pvec;
                 pagevec_init(&lru_pvec, 0);
                 for (page_idx = 0; page_idx < nr_pages; page_idx++) {
-                        struct page *page = list_to_page(pages);
+                        struct page *page = list_entry(pages->prev, struct page, lru);
+                        prefetchw(&page->flags);
                         list_del(&page->lru);
                         if (!add_to_page_cache(page, mapping,
                                                page->index, GFP_KERNEL)) {
@@ -298,8 +297,9 @@ static int gfs2_readpages(struct file *file, struct address_space *mapping,
                                 unlock_page(page);
                                 if (!pagevec_add(&lru_pvec, page))
                                          __pagevec_lru_add(&lru_pvec);
+                        } else {
+                                page_cache_release(page);
                         }
-                        page_cache_release(page);
                 }
                 pagevec_lru_add(&lru_pvec);
                 ret = 0;
@@ -321,7 +321,7 @@ out_noerror:
 out_unlock:
         /* unlock all pages, we can't do any I/O right now */
         for (page_idx = 0; page_idx < nr_pages; page_idx++) {
-                struct page *page = list_to_page(pages);
+                struct page *page = list_entry(pages->prev, struct page, lru);
                 list_del(&page->lru);
                 unlock_page(page);
                 page_cache_release(page);