linux-kernel - Re: [PATCH] btrfs: zero out delayed node upon allocation

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Message-ID: <20151025195055.GA5021@gmail.com>
Date:	Sun, 25 Oct 2015 19:50:55 +0000
From:	Alexandru Moise <00moses.alexander00@...il.com>
To:	Jeff Mahoney <jeffm@...e.com>
Cc:	clm@...com, jbacik@...com, dsterba@...e.com,
	linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] btrfs: zero out delayed node upon allocation

> > This allows us to trim out half of btrfs_init_delayed_node() which
> > is now reduntant.
> 
> It's redundant if kmem_cache_zalloc is used, but you haven't
> documented that doing so is now required.  For all of these changes
> you've posted, if they're to be accepted, I'd really prefer to set up
> the slab with a constructor instead.  Then we don't need to worry
> about such guarantees.  The object returned via kmem_cache_alloc will
> always be properly initialized.

Well I wouldn't say it's *required* just makes this particular piece
of code neater, since we memset-zero the node's inode_item _anyways_.
I like the constructor idea though, do you suggest I should invest in
that idea?

> 
> This makes assumptions about atomic_t and what atomic_set does that
> aren't guaranteed to be true.  When accessors/mutators are part of the
> API they should be used.
> 
> - -Jeff

You're right, taking out that atomic_set was really stupid. I'll
resent the patch with a proper explanation in the commit message and
put the atomic_set back.

Unless you feel that the change is rather pointless, I'll gladly back
off :-).

Regards,
	Alex
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