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authorNeilBrown <neilb@suse.de>2014-12-15 12:56:59 +1100
committerNeilBrown <neilb@suse.de>2015-02-06 09:32:55 +1100
commitb7b17c9b67e5984210c83d50d2c8117d3bd50ea0 (patch)
tree072e63fa9cd1e1c314d9d99d0ae77d9e955d1a38
parent7b1485bab9c49b0d3811d72beb0de60c7b8b337d (diff)
downloadlinux-b7b17c9b67e5984210c83d50d2c8117d3bd50ea0.tar.bz2
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>
-rw-r--r--drivers/md/bitmap.c13
-rw-r--r--drivers/md/md.c23
2 files changed, 20 insertions, 16 deletions
diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 3424b1915fc4..3a5767968ba0 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -2211,11 +2211,13 @@ __ATTR(metadata, S_IRUGO|S_IWUSR, metadata_show, metadata_store);
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 @@ __ATTR(can_clear, S_IRUGO|S_IWUSR, can_clear_show, can_clear_store);
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 eb0c3b576d7d..dbbe5e6df24c 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4042,20 +4042,21 @@ static ssize_t
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 @@ md_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
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;
}