[AUTOSEL,4.18,095/100] ocfs2: fix crash in ocfs2_duplicate_clusters_by_page()
diff mbox series

Message ID 20181016041221.135528-95-sashal@kernel.org
State New, archived
Headers show
  • [AUTOSEL,4.18,001/100] xfrm: Validate address prefix lengths in the xfrm selector.
Related show

Commit Message

Sasha Levin Oct. 16, 2018, 4:12 a.m. UTC
From: Larry Chen <lchen@suse.com>

[ Upstream commit 69eb7765b9c6902444c89c54e7043242faf981e5 ]

ocfs2_duplicate_clusters_by_page() may crash if one of the extent's pages
is dirty.  When a page has not been written back, it is still in dirty
state.  If ocfs2_duplicate_clusters_by_page() is called against the dirty
page, the crash happens.

To fix this bug, we can just unlock the page and wait until the page until
its not dirty.

The following is the backtrace:

kernel BUG at /root/code/ocfs2/refcounttree.c:2961!
[exception RIP: ocfs2_duplicate_clusters_by_page+822]
__ocfs2_move_extent+0x80/0x450 [ocfs2]
? __ocfs2_claim_clusters+0x130/0x250 [ocfs2]
ocfs2_defrag_extent+0x5b8/0x5e0 [ocfs2]
__ocfs2_move_extents_range+0x2a4/0x470 [ocfs2]
ocfs2_move_extents+0x180/0x3b0 [ocfs2]
? ocfs2_wait_for_recovery+0x13/0x70 [ocfs2]
ocfs2_ioctl_move_extents+0x133/0x2d0 [ocfs2]
ocfs2_ioctl+0x253/0x640 [ocfs2]

Once we find the page is dirty, we do not wait until it's clean, rather we
use write_one_page() to write it back

Link: http://lkml.kernel.org/r/20180829074740.9438-1-lchen@suse.com
[lchen@suse.com: update comments]
  Link: http://lkml.kernel.org/r/20180830075041.14879-1-lchen@suse.com
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Larry Chen <lchen@suse.com>
Acked-by: Changwei Ge <ge.changwei@h3c.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <jiangqi903@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
 fs/ocfs2/refcounttree.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff mbox series

diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 7869622af22a..7a5ee145c733 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -2946,6 +2946,7 @@  int ocfs2_duplicate_clusters_by_page(handle_t *handle,
 		if (map_end & (PAGE_SIZE - 1))
 			to = map_end & (PAGE_SIZE - 1);
 		page = find_or_create_page(mapping, page_index, GFP_NOFS);
 		if (!page) {
 			ret = -ENOMEM;
@@ -2954,11 +2955,18 @@  int ocfs2_duplicate_clusters_by_page(handle_t *handle,
-		 * In case PAGE_SIZE <= CLUSTER_SIZE, This page
-		 * can't be dirtied before we CoW it out.
+		 * In case PAGE_SIZE <= CLUSTER_SIZE, we do not expect a dirty
+		 * page, so write it back.
-		if (PAGE_SIZE <= OCFS2_SB(sb)->s_clustersize)
-			BUG_ON(PageDirty(page));
+		if (PAGE_SIZE <= OCFS2_SB(sb)->s_clustersize) {
+			if (PageDirty(page)) {
+				/*
+				 * write_on_page will unlock the page on return
+				 */
+				ret = write_one_page(page);
+				goto retry;
+			}
+		}
 		if (!PageUptodate(page)) {
 			ret = block_read_full_page(page, ocfs2_get_block);