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md: remove mddev_lock() from md_attr_show()

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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>
This commit is contained in:
NeilBrown
2014-12-15 12:56:59 +11:00
parent 7b1485bab9
commit b7b17c9b67
2 changed files with 20 additions and 16 deletions
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13
drivers/md/bitmap.c
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@@ -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