From mboxrd@z Thu Jan 1 00:00:00 1970 From: "J. R. Okajima" Subject: Re: [rfc] new stat*fs-like syscall? Date: Tue, 06 Jul 2010 08:31:30 +0900 Message-ID: <6419.1278372690@jrobl> References: <20100624131455.GA10441@laptop> <7897.1277531612@jrobl> <20100626093544.GA27715@infradead.org> <13226.1277556884@jrobl> <20100705205806.GA12517@cynthia.pants.nu> Cc: Christoph Hellwig , Nick Piggin , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Al Viro , Ulrich Drepper , Linus Torvalds To: Brad Boyer Return-path: In-Reply-To: <20100705205806.GA12517@cynthia.pants.nu> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org 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