4.14-stable review patch. If anyone has any objections, please let me know.
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[ 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] do_vfs_ioctl+0x90/0x5f0 SyS_ioctl+0x74/0x80 do_syscall_64+0x74/0x140 entry_SYSCALL_64_after_hwframe+0x3d/0xa2
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 --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c index 1b1283f07941..824f407df1db 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);
+retry: 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);