Re: Reading and Writing to Block from di_spare

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Reading and Writing to Block from di_spare
\ Adam (17 Jan 2008)
. \ David Schultz (17 Jan 2008)
. . \ Adam (17 Jan 2008)
. . . \ David Schultz (17 Jan 2008)

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Subject:	Re: Reading and Writing to Block from di_spare
Group:	Freebsd-current
From:	David Schultz
Date:	17 Jan 2008

On Thu, Jan 17, 2008, Adam wrote:
> David,
> I understand that there is no routine to read and write specifically
> to an address contained in the di_spare. I also understand that
> di_spare is currently unused and has no specific manipulators.
>
> Allow me to clarify. I am looking for a way to take a ufs2_daddr_t
> (which is neither a direct nor indirect block of a di_node) and read/
> write to that address.

To do it cleanly you'd probably need to hack ufs_bmap and
ffs_balloc to map your 'extra' block to a particular LBN (or at
least that's the only way I know how to do it easily.) But as I
said before, if you just need to store a small amount of
information, extended attributes are most likely a much simpler
alternative.
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