[Btrfs-devel] btrfs and git-reflog

Theodore Tso tytso at MIT.EDU
Fri Jan 25 13:28:04 PST 2008

On Fri, Jan 25, 2008 at 01:55:37PM -0500, Chris Mason wrote:
> Since btrfs maintains both a name index and an inode index, I can
> iterate over the name index (hash values) for use cases that require
> telldir/seekdir.  At any rate, there are a variety of choices for
> working around it, but I'm focusing on the disk format first ;)

Well, there is a disk format way of handling the problem, and which is
what JFS used; it simply maintained associated a separate "telldir"
cookie for each file, and had separate b-tree which allowed for fast
access each file given its telldir cookie.  btrfs could theoretically
do something similar.  I'd suggest thinking about this as an optional
feature, which would be enabled if full 100% reliable telldir/seekdir
support is required, or for NFS servers.   

There are indeed workarounds, but unfortunately they all have

						- Ted

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