md/r5cache: call mddev_lock/unlock() in r5c_journal_mode_show

In r5c_journal_mode_show(), it is necessary to call mddev_lock()
before accessing conf and conf->log. Otherwise, the conf->log
may change (and become NULL).

Signed-off-by: Song Liu <songliubraving@fb.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Shaohua Li <shli@fb.com>
This commit is contained in:
Song Liu 2017-08-08 22:56:52 -07:00 committed by Shaohua Li
parent 26e13043b7
commit a72cbf83b0

View File

@ -2529,11 +2529,18 @@ static void r5l_write_super(struct r5l_log *log, sector_t cp)
static ssize_t r5c_journal_mode_show(struct mddev *mddev, char *page)
{
struct r5conf *conf = mddev->private;
struct r5conf *conf;
int ret;
if (!conf->log)
ret = mddev_lock(mddev);
if (ret)
return ret;
conf = mddev->private;
if (!conf || !conf->log) {
mddev_unlock(mddev);
return 0;
}
switch (conf->log->r5c_journal_mode) {
case R5C_JOURNAL_MODE_WRITE_THROUGH:
@ -2551,6 +2558,7 @@ static ssize_t r5c_journal_mode_show(struct mddev *mddev, char *page)
default:
ret = 0;
}
mddev_unlock(mddev);
return ret;
}