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From: David Howells <dhowells@redhat.com>
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References: <20170330025620.GA789@zzz> <859.1490824354@warthog.procyon.org.uk> <29183.1490711359@warthog.procyon.org.uk> <5587.1490831828@warthog.procyon.org.uk> <20170330002328.GD4864@birch.djwong.org>
Subject: Re: The XFS_IOC_FSGEOMETRY ioctl doesn't like fds that are opened O_PATH
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Date: Thu, 30 Mar 2017 09:03:54 +0100
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To: Eric Biggers <ebiggers3@gmail.com>
Cc: dhowells@redhat.com, "Darrick J. Wong" <darrick.wong@oracle.com>, linux-xfs <linux-xfs@vger.kernel.org>, Andreas Dilger <adilger@dilger.ca>, Christoph Hellwig <hch@infradead.org>, linux-fsdevel@vger.kernel.org, Eric Sandeen <sandeen@sandeen.net>

Eric Biggers <ebiggers3@gmail.com> wrote:

> Also, ioctl() with an O_PATH file descriptor always fails with EBADF because
> sys_ioctl() uses fdget() rather than fdget_raw().  The filesystem isn't
> involved at all.  This is intentional, I believe.

Yeah.  Apparently so, though some ioctls might make sense if they're asking
about the filesystem.

Anyway, I need to fix xfs_io for that now too if I'm going to use that.  I
wonder what xfs_io needs the geometry for.

I'm getting the impression xfs_io isn't really the tool I should be using for
this.

Dvid