Re: [rfc] new stat*fs-like syscall?

From: J. R. Okajima
Date: Mon Jul 05 2010 - 19:32:38 EST



Brad Boyer:
> I would suggest making it an inode operation if we do actually add it. Most
> cases are going to be per super-block, but it might be easier to transparently
> handle things like _PC_PIPE_BUF in glibc if it could call an fpathconf type
> system call on the pipe fd. I haven't looked at the current glibc code for
> that particular selector. The only one I looked at in any detail was
> _PC_LINK_MAX, which is the one you already discussed and is obviously a
> per-sb option. The only drawback I can see is that making it an inode
> operation would make the vfs_pathconf fail on a negative dentry, but that
> seems like a very strange thing to support in any case.

Recently the size of the pipe buffer becomes customizable, doesn't it?
For _PC_PIPE_BUF, fpathconf should issue fcntl(F_GETPIPE_SZ).

For negative dentry, it should be supported as long as some
standard/specification doesn't prohibit explicitly. So I still think
statfs is the best place to implement _PC_LINK_MAX.


J. R. Okajima
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