[GFS2] Fix lack of buffers in writepage bug

In some cases we can enter write page without there being buffers
attached to the page. In this case the function to add gfs2_bufdata
to the buffers fails sliently causing further failures down the
stack.

This fix ensures that we always add buffers in writepage if they
didn't already exist (mmap is one way to trigger this).

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/ops_address.c b/fs/gfs2/ops_address.c
index bdd4d6b487219e3d6d3855599d9abc879d24a800..45afd0508689a4ef39174fae366f9db2b621db74 100644 (file)
--- a/fs/gfs2/ops_address.c
+++ b/fs/gfs2/ops_address.c
@@ -131,8 +131,8 @@ static int get_block_noalloc(struct inode *inode, sector_t lblock,
 static int gfs2_writepage(struct page *page, struct writeback_control *wbc)
 {
        struct inode *inode = page->mapping->host;
-       struct gfs2_inode *ip = GFS2_I(page->mapping->host);
-       struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
+       struct gfs2_inode *ip = GFS2_I(inode);
+       struct gfs2_sbd *sdp = GFS2_SB(inode);
        loff_t i_size = i_size_read(inode);
        pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
        unsigned offset;
@@ -158,6 +158,10 @@ static int gfs2_writepage(struct page *page, struct writeback_control *wbc)
                error = gfs2_trans_begin(sdp, RES_DINODE + 1, 0);
                if (error)
                        goto out_ignore;
+               if (!page_has_buffers(page)) {
+                       create_empty_buffers(page, inode->i_sb->s_blocksize,
+                                            (1 << BH_Dirty)|(1 << BH_Uptodate));
+               }
                gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize-1);
                done_trans = 1;
        }