Question about commit f9a67b1182e5 ("md/bitmap: clear bitmap if bitmap_create failed").

From: Christophe JAILLET
Date: Mon Sep 12 2016 - 15:10:05 EST


I'm puzzled by commit f9a67b1182e5 ("md/bitmap: clear bitmap if bitmap_create failed").

Part of the commit is:

@@ -1865,8 +1866,10 @@ int bitmap_copy_from_slot(struct mddev *mddev, int slot,
struct bitmap_counts *counts;
struct bitmap *bitmap = bitmap_create(mddev, slot);

- if (IS_ERR(bitmap))
+ if (IS_ERR(bitmap)) {
+ bitmap_free(bitmap);
return PTR_ERR(bitmap);
+ }

but if 'bitmap' is an error, I think that bad things will happen in 'bitmap_free()' when, at the beginning of the function, we will execute:

if (bitmap->sysfs_can_clear) <-----------------

However, the commit log message is really explicit and adding this call to 'bitmap_free' has really been done one purpose. ("If bitmap_create returns an error, we need to call either bitmap_destroy or bitmap_free to do clean up, ...")

It is also not consistent with the comment before function bitmap_create():

* if this returns an error, bitmap_destroy must be called to do clean up
* once mddev->bitmap is set

I may have missed something, but I don't see what.

Is this commit correct?

Best regards,