On Wed, Mar 29, 2017 at 07:56:20PM -0700, Eric Biggers wrote: > On Wed, Mar 29, 2017 at 05:23:28PM -0700, Darrick J. Wong wrote: > > On Thu, Mar 30, 2017 at 12:57:08AM +0100, David Howells wrote: > > > Should XFS_IOC_FSGEOMETRY work on fds that are opened O_PATH on an XFS > > > filesystem? Or should xfs_io not call that ioctl on O_PATH fds? > > > > Given that read/write don't work under O_PATH, I wouldn't expect ioctls > > to work either. > > > > I tried to write a two line program to call FSGEOMETRY to see what > > actually happens but got so bogged down in trying to figure out what > > magic incantation of C headers one needs to pull in the appropriate > > structure typedefs for an ioctl I wasn't even trying to call that I gave > > up. > > > > Seriously, what the f*ck do you have to #include just to be able to use > > O_PATH? > > From open(2): > > "The O_DIRECT, O_NOATIME, O_PATH, and O_TMPFILE flags are > Linux-specific. One must define _GNU_SOURCE to obtain their definitions." Ah, thank you. I missed that, having skipped straight to the section on O_PATH... ($deity I hate userspace) > 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. Yes, it is. --D > > - Eric
