On Fri, Nov 17, 2017 at 05:23:11PM -0800, Song Liu wrote:

r5c_journal_mode_set() is called by r5c_journal_mode_store() and raid_ctr() in dm-raid. We don't need mddev_lock() when calling from raid_ctr(). This patch fixes this by moves the mddev_lock() to r5c_journal_mode_store().

Cc: stable@vger.kernel.org (v4.13+) Signed-off-by: Song Liu songliubraving@fb.com

---

drivers/md/raid5-cache.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c index f1c86d9..e01f229 100644 --- a/drivers/md/raid5-cache.c +++ b/drivers/md/raid5-cache.c @@ -2583,25 +2583,19 @@ int r5c_journal_mode_set(struct mddev *mddev, int mode) mode > R5C_JOURNAL_MODE_WRITE_BACK) return -EINVAL;

• err = mddev_lock(mddev); if (err) return err;

please make sure your code doesn't have compiling warnning. The 'err' is an obvious 'use before initialization' warnning.

conf = mddev->private;

• if (!conf || !conf->log) {

• mddev_unlock(mddev);
  

• if (!conf || !conf->log) return -ENODEV;

• }

if (raid5_calc_degraded(conf) > 0 &&

•    mode == R5C_JOURNAL_MODE_WRITE_BACK) {
  

• mddev_unlock(mddev);
  

•    mode == R5C_JOURNAL_MODE_WRITE_BACK)
  

  return -EINVAL;

• }

mddev_suspend(mddev); conf->log->r5c_journal_mode = mode; mddev_resume(mddev);

• mddev_unlock(mddev);

pr_debug("md/raid:%s: setting r5c cache mode to %d: %s\n", mdname(mddev), mode, r5c_journal_mode_str[mode]); @@ -2614,6 +2608,7 @@ static ssize_t r5c_journal_mode_store(struct mddev *mddev, { int mode = ARRAY_SIZE(r5c_journal_mode_str); size_t len = length;

• int ret;

if (len < 2) return -EINVAL; @@ -2625,8 +2620,10 @@ static ssize_t r5c_journal_mode_store(struct mddev *mddev, if (strlen(r5c_journal_mode_str[mode]) == len && !strncmp(page, r5c_journal_mode_str[mode], len)) break;

• return r5c_journal_mode_set(mddev, mode) ?: length;

• mddev_lock(mddev);

and you don't check return value for mddev_lock, which has __must_check marked.

• ret = r5c_journal_mode_set(mddev, mode);
• mddev_unlock(mddev);
• return ret ?: length;

} struct md_sysfs_entry -- 2.9.5