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Date: Thu, 3 Sep 2009 14:50:52 +0000 (UTC) From: Eric Blake <ebb9@....net> To: linux-kernel@...r.kernel.org Subject: Re: make getdents/readdir POSIX compliant wrt mount-point dirent.d_ino Ulrich Drepper <drepper <at> gmail.com> writes: > I guess that this is really a difficult way to solve. I wouldn't want > to pay for something which is hardly ever really used. > > But there are programs out there which would like to use the inode > uniqueness. Therefore the next best thing to do is perhaps to return > a flag in the getdents information (in d_type, perhaps) to indicate > that this is a mount point and/or that there are multiple ways to > access the file in question. Then programs which can use the inode > information can be watching for this flag and enter the slow path only > if it's set. An alternative to a flag in d_type might be setting d_ino to a sentinel value (there is plenty of existing code that refuses to use a readdir entry with d_ino of 0, so it would have to be something else; but maybe -1 would work). But I definitely like your idea of making it obvious to the application (whether by d_ino or d_type) when it is necessary to use lstat to validate the inode number, and promising that if the flag is not set then d_ino is correct. -- Eric Blake -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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