Re: [RFC][PATCH] ChunkFS: fs fission for faster fsck

Valerie Henson
2007-05-01T17:27:06Z

On Fri, Apr 27, 2007 at 11:06:47AM -0400, Jeff Dike wrote:
> On Thu, Apr 26, 2007 at 09:58:25PM -0700, Valerie Henson wrote:
> > Here's an example, spelled out:
> >
> > Allocate file 1 in chunk A.
> > Grow file 1.
> > Chunk A fills up.
> > Allocate continuation inode for file 1 in chunk B.
> > Chunk A gets some free space.
> > Chunk B fills up.
> > Pick chunk A for allocating next block of file 1.
> > Try to look up a continuation inode for file 1 in chunk A.
> > Continuation inode for file 1 found in chunk A!
> > Attach newly allocated block to existing inode for file 1 in chunk A.
>
> So far, so good (and the slides are helpful, tx!). What happens when
> file 1 keeps growing and chunk A fills up (and chunk B is still full)?
> Can the same continuation inode also point at chunk C, where the file
> is going to grow to?

You allocate a new continuation inode in chunk C. The rule is that
only inodes inside a chunk can point to blocks inside the chunk, so
you need an inode in C if you want to allocate blocks from C.

-VAL