On 2012-08-14, at 9:19, Theodore Ts'o [off-list ref] wrote:
On Tue, Aug 14, 2012 at 03:04:47PM +0800, Tao Ma wrote:
quoted
As andreas said in another e-mail, that would make the codes a little
complex. So in general, in my previous version, I just tried to refactor
most of the codes so that they can work for both inline inode and dir
blocks. But if these changes are merged, we have to re-write all of the
codes that are currently shared, such as ext4_find_entry, empty_dir,
ext4_add_entry etc.
Well, we may not need to rewrite as much as you think. For one thing,
as I mentioned, I don't think the VFS passes '.' and '..' lookup
requests down to the file system anyway, and even if it did, you could
just have a function which checks for '.' and '..' and returns the
correct value if necessary.
Actually, NFS can submit lookups for ".." for path linkage IIRC, since we had to implement a patch to fix this for ext4 and Lustre at one time.
So I think you wouldn't need to rewrite
all of these functions, since the fundamental layout of the directory
wouldn't be changing. It's just that we're skipping the '.' and '..'
entries, and the "standard" directory layout would be starting 4 bytes
later (after the '..' inode number).
Agreed, the "." and ".." lookups are already special cases in the lookup code.
Cheers, Andreas
So it's probably worth taking a look to see how much of an increase in
complexity would actually be involved.
Regards,
- Ted
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