Commit 69eb7765 authored by Larry Chen's avatar Larry Chen Committed by Greg Kroah-Hartman

ocfs2: fix crash in ocfs2_duplicate_clusters_by_page()

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: default avatarLarry Chen <lchen@suse.com>
Acked-by: default avatarChangwei 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent dff11abe
......@@ -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);
......
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