[PATCH 4.9 083/101] f2fs: fix a panic caused by NULL flush_cmd_control

From: Greg Kroah-Hartman
Date: Thu Dec 06 2018 - 09:50:08 EST


4.9-stable review patch. If anyone has any objections, please let me know.

------------------

From: Yunlei He <heyunlei@xxxxxxxxxx>

commit d4fdf8ba0e5808ba9ad6b44337783bd9935e0982 upstream.

Mount fs with option noflush_merge, boot failed for illegal address
fcc in function f2fs_issue_flush:

if (!test_opt(sbi, FLUSH_MERGE)) {
ret = submit_flush_wait(sbi);
atomic_inc(&fcc->issued_flush); -> Here, fcc illegal
return ret;
}

Signed-off-by: Yunlei He <heyunlei@xxxxxxxxxx>
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
[bwh: Backported to 4.9: adjust context]
Signed-off-by: Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/f2fs/segment.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -493,6 +493,9 @@ int create_flush_cmd_control(struct f2fs
init_waitqueue_head(&fcc->flush_wait_queue);
init_llist_head(&fcc->issue_list);
SM_I(sbi)->cmd_control_info = fcc;
+ if (!test_opt(sbi, FLUSH_MERGE))
+ return err;
+
fcc->f2fs_issue_flush = kthread_run(issue_flush_thread, sbi,
"f2fs_flush-%u:%u", MAJOR(dev), MINOR(dev));
if (IS_ERR(fcc->f2fs_issue_flush)) {
@@ -2539,7 +2542,7 @@ int build_segment_manager(struct f2fs_sb

INIT_LIST_HEAD(&sm_info->sit_entry_set);

- if (test_opt(sbi, FLUSH_MERGE) && !f2fs_readonly(sbi->sb)) {
+ if (!f2fs_readonly(sbi->sb)) {
err = create_flush_cmd_control(sbi);
if (err)
return err;