Re: [PATCH v3 1/5] add metadata_incore ioctl in vfs

[Shaohua Li <shaohua.li@xxxxxxxxx>]

On Thu, 2011-01-20 at 13:55 +0800, Andrew Morton wrote:
> On Thu, 20 Jan 2011 13:38:18 +0800 Shaohua Li <shaohua.li@xxxxxxxxx> wrote:
> 
> > > ext2, minix and probably others create an address_space for each
> > > directory.  Heaven knows what xfs does (for example).
> > yes, this is for one directiory, but the all files's metadata are in
> > block_dev address_space.
> > I thought you mean there are several block_dev address_space like
> > address_space in some filesystems, which doesn't fit well in my
> > implementation. for ext like filesystem, there is only one
> > address_space. for filesystems with several address_space, my proposal
> > is map them to a virtual big address_space in the new ioctls.
> 
> ext2 and minixfs (and I think sysv and ufs) have a separate
> address_space for each directory.  I don't see how those can be
> represented with a single "virtual big address_space" - we also need
> identifiers in there so each directory's address_space can be created
> and appropriately populated.
Oh, I misunderstand your comments. you are right, the ioctl methods
don't work for ext2. the dir's address_space can't be readahead either.
Looks we could only do the metadata readahead in filesystem specific
way.

Thanks,
Shaohua

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