f2fs: read page index before freeing

commit 0ea295dd853e0879a9a30ab61f923c26be35b902 upstream.

The function truncate_node frees the page with f2fs_put_page. However,
the page index is read after that. So, the patch reads the index before
freeing the page.

Fixes: bf39c00a9a7f ("f2fs: drop obsolete node page when it is truncated")
Signed-off-by: Pan Bian <bianpan2016@163.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 4b697ccc9b0cd248003062a34d0bea8fda720428..a4d72544f3ff887b5e9a759cc4b2996dcc663b5b 100644 (file)
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -509,6 +509,7 @@ static void truncate_node(struct dnode_of_data *dn)
 {
        struct f2fs_sb_info *sbi = F2FS_SB(dn->inode->i_sb);
        struct node_info ni;
+       pgoff_t index;
 
        get_node_info(sbi, dn->nid, &ni);
        if (dn->inode->i_blocks == 0) {
@@ -532,10 +533,11 @@ invalidate:
        clear_node_page_dirty(dn->node_page);
        F2FS_SET_SB_DIRT(sbi);
 
+       index = dn->node_page->index;
        f2fs_put_page(dn->node_page, 1);
 
        invalidate_mapping_pages(NODE_MAPPING(sbi),
-                       dn->node_page->index, dn->node_page->index);
+                       index, index);
 
        dn->node_page = NULL;
        trace_f2fs_truncate_node(dn->inode, dn->nid, ni.blk_addr);