From b7b17c9b67e5984210c83d50d2c8117d3bd50ea0 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 15 Dec 2014 12:56:59 +1100 Subject: 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 --- drivers/md/bitmap.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) (limited to 'drivers/md/bitmap.c') 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 -- cgit v1.2.3