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Re: [PATCH 00/26] generic btree implementation, version 3

To: Christoph Hellwig <hch@xxxxxx>, xfs@xxxxxxxxxxx
Subject: Re: [PATCH 00/26] generic btree implementation, version 3
From: Christoph Hellwig <hch@xxxxxx>
Date: Mon, 4 Aug 2008 16:21:32 +0200
In-reply-to: <20080804015425.GE6119@disturbed>
References: <20080804013158.GA8819@xxxxxx> <20080804015425.GE6119@disturbed>
Sender: xfs-bounce@xxxxxxxxxxx
User-agent: Mutt/1.3.28i
On Mon, Aug 04, 2008 at 11:54:25AM +1000, Dave Chinner wrote:
> > I'm not sure
> > what to do with move_* - these are the most ugly helpers, so maybe
> > we should just make them memmove wrappers in the style of copy_
> > and leave all addressing to the callers.
> 
> Yes, it would be nice to have them use the same interface. If
> we do that, then there's no real point for having a copy vs move
> distinction - we could just make everything use the
> memmove version and drop one of the interfaces altogether....

I've actually come up with another variant.  Since what we do in the
memmove case is to move a number of entries in a single block up or down
one position I've added the following helper:

STATIC void
xfs_btree_shift_keys(
        struct xfs_btree_cur    *cur,
        union xfs_btree_key     *key
        int                     dir,
        int                     numkeys)
{
        char                    *dst_key;

        ASSERT(numkeys >= 0);
        ASSERT(dir == 1 || dir == -1);

        dst_key = (char *)key + (dir * cur->bc_ops->key_len);
        memmove(dst_key, key, numkeys * cur->bc_ops->key_len);
}

and the same for ptrs and recs.  This follows the original code in
spirit and is quite readable.


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