On 26-09-14 19:04, Jeremy Allison wrote:
On Fri, Sep 26, 2014 at 09:56:05AM -0700, Christoph Hellwig wrote:
My take on this is:
- I think we'll have to prevent non-utf8 file names for any cases where
we use utf8 normalization. If you do not use utf8 normalization
it's plain old Unix everything is allowed.
- I think utf8 normalization vs not should be mkfs option, to make sure
everyone including kernel and repair knows what sort of filesystem
deal with.
- case insensitive matching for utf8 normalized filesystems should be
a runtime decision. mount time for now, but Samba people would be
extremly happy to allow per-operation or per-process CI matching.
But that is another totally different discusion I'd like to keep
separate, I just want to make sure the disk format allows for it for
now.
Actually, I'm so eager for case-insensitive matching I'd
take "at format time", as with ZFS :-) :-).
My argument against "mount time case-insensitivity" and for "mkfs time
case-insensitivity" is related to switching from the case-sensitive domain
to the case-insensitive one.
For case-sensitive, from "README" to "readme" there are 64 different
possible filenames. Let's say you create 63 out of these 64. Now remount
the filesystem case-insensitive, and try to open by the 64th version of
"readme". It is not an exact match for any of the 63 candidate files, and a
case-insensitive match to all 63 candidate files. Which of these 63 files
should be opened, and why that one in particular?
Having CI matching can speed up Samba operations by a
factor of 10 on large directories (warning, number made
up, depending on the number of entries per dir :-).
I really want that to be true, but the proof of the pudding...
Olaf
--
Olaf Weber SGI Phone: +31(0)30-6696796
Veldzigt 2b Fax: +31(0)30-6696799
Technical Lead 3454 PW de Meern Vnet: 955-6796
Storage Software The Netherlands Email: olaf@xxxxxxx
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