md: remove mddev_lock() from md_attr_show()
Most attributes can be read safely without any locking.
A race might lead to a slightly out-dated value, but nothing wrong.
We already have locking in some places where needed.
All that remains is can_clear_show(), behind_writes_used_show()
and action_show() which are easily fixed.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 3424b19..3a57679 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -2211,11 +2211,13 @@
static ssize_t can_clear_show(struct mddev *mddev, char *page)
{
int len;
+ spin_lock(&mddev->lock);
if (mddev->bitmap)
len = sprintf(page, "%s\n", (mddev->bitmap->need_sync ?
"false" : "true"));
else
len = sprintf(page, "\n");
+ spin_unlock(&mddev->lock);
return len;
}
@@ -2240,10 +2242,15 @@
static ssize_t
behind_writes_used_show(struct mddev *mddev, char *page)
{
+ ssize_t ret;
+ spin_lock(&mddev->lock);
if (mddev->bitmap == NULL)
- return sprintf(page, "0\n");
- return sprintf(page, "%lu\n",
- mddev->bitmap->behind_writes_used);
+ ret = sprintf(page, "0\n");
+ else
+ ret = sprintf(page, "%lu\n",
+ mddev->bitmap->behind_writes_used);
+ spin_unlock(&mddev->lock);
+ return ret;
}
static ssize_t