[PATCH] f2fs: fix a panic caused by NULL flush_cmd_control

From: Yunlei He <heyunlei@huawei.com>
To: jaegeuk@kernel.org, yuchao0@huawei.com,
	linux-f2fs-devel@lists.sourceforge.net
Subject: [PATCH] f2fs: fix a panic caused by NULL flush_cmd_control
Date: Thu, 1 Jun 2017 16:43:51 +0800	[thread overview]
Message-ID: <1496306631-23944-1-git-send-email-heyunlei@huawei.com> (raw)

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@huawei.com>
---
 fs/f2fs/segment.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index a8f4c81..029b5ea 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -566,6 +566,9 @@ int create_flush_cmd_control(struct f2fs_sb_info *sbi)
 	init_waitqueue_head(&fcc->flush_wait_queue);
 	init_llist_head(&fcc->issue_list);
 	SM_I(sbi)->fcc_info = fcc;
+	if (!test_opt(sbi, FLUSH_MERGE))
+		return err;
+
 init_thread:
 	fcc->f2fs_issue_flush = kthread_run(issue_flush_thread, sbi,
 				"f2fs_flush-%u:%u", MAJOR(dev), MINOR(dev));
@@ -3239,7 +3242,7 @@ int build_segment_manager(struct f2fs_sb_info *sbi)
 
 	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;
-- 
1.9.1


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