md: protect ->pers changes with mddev->lock
->pers is already protected by ->reconfig_mutex, and
cannot possibly change when there are threads running or
outstanding IO.
However there are some places where we access ->pers
not in a thread or IO context, and where ->reconfig_mutex
is unnecessarily heavy-weight: level_show and md_seq_show().
So protect all changes, and those accesses, with ->lock.
This is a step toward taking those accesses out from under
reconfig_mutex.
[Fixed missing "mddev->pers" -> "pers" conversion, thanks to
Dan Carpenter <dan.carpenter@oracle.com>]
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 37e7c17..e41559d 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -391,6 +391,7 @@
* rdev superblocks, events
* clearing MD_CHANGE_*
* in_sync - and related safemode and MD_CHANGE changes
+ * pers (also protected by reconfig_mutex and pending IO).
*/
spinlock_t lock;
wait_queue_head_t sb_wait; /* for waiting on superblock updates */