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
diff --git a/drivers/md/md.c b/drivers/md/md.c
index eb0c3b5..dbbe5e6 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4042,20 +4042,21 @@
action_show(struct mddev *mddev, char *page)
{
char *type = "idle";
- if (test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
+ unsigned long recovery = mddev->recovery;
+ if (test_bit(MD_RECOVERY_FROZEN, &recovery))
type = "frozen";
- else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
- (!mddev->ro && test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))) {
- if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
+ else if (test_bit(MD_RECOVERY_RUNNING, &recovery) ||
+ (!mddev->ro && test_bit(MD_RECOVERY_NEEDED, &recovery))) {
+ if (test_bit(MD_RECOVERY_RESHAPE, &recovery))
type = "reshape";
- else if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
- if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
+ else if (test_bit(MD_RECOVERY_SYNC, &recovery)) {
+ if (!test_bit(MD_RECOVERY_REQUESTED, &recovery))
type = "resync";
- else if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
+ else if (test_bit(MD_RECOVERY_CHECK, &recovery))
type = "check";
else
type = "repair";
- } else if (test_bit(MD_RECOVERY_RECOVER, &mddev->recovery))
+ } else if (test_bit(MD_RECOVERY_RECOVER, &recovery))
type = "recover";
}
return sprintf(page, "%s\n", type);
@@ -4572,11 +4573,7 @@
mddev_get(mddev);
spin_unlock(&all_mddevs_lock);
- rv = mddev_lock(mddev);
- if (!rv) {
- rv = entry->show(mddev, page);
- mddev_unlock(mddev);
- }
+ rv = entry->show(mddev, page);
mddev_put(mddev);
return rv;
}