[ACL-Devel] FS meta information (properties/attributes/...)

[Andreas Gruenbacher]

After looking at some documentation, i'm more convinced that we should really go
for a general mechanism to store extended attributes for inodes. From what I saw
so far, name/value pairs seem to be the right thing.

It seems no problem to use simple ASCII strings for the names. In IRIX 6.5
attr(1) the name is limited to 256 characters. Again, this seems to be a sane
assumption.

Now there again is a choice. Do we need arbitrary length attributes?

If so, the interface would need to be file-like, with several levels of
indirection etc. (the full overheads). Otherwise, the data of one attribute can
be passed to/from the kernel in a fixed-size buffer. I'd prefer the latter,
again for efficiency reasons. Any other opinions?

Also, a fixed upper limit (say, 256K) would allow a simple allocation scheme on
the filesystem (one level of indirection should do). Does anybody know if/how
the existing code can be reused?

I guess Linda said Irix would support arbitrary length attributes. At least in
the man page referenced above, it says the limit is 256K. Was that limit lifted
recently?

Is anybody working on an attribute storage system already?


Andreas

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 Andreas Gruenbacher, a.gruenbacher@computer.org
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