On Thu, Sep 08, 2016 at 04:39:34PM -0400, CAI Qian wrote: > > > ----- Original Message ----- > > From: "Linus Torvalds" <torvalds@xxxxxxxxxxxxxxxxxxxx> > > To: "CAI Qian" <caiqian@xxxxxxxxxx> > > Cc: "Dave Chinner" <david@xxxxxxxxxxxxx>, "Al Viro" <viro@xxxxxxxxxxxxxxxxxx>, "linux-xfs" > > <linux-xfs@xxxxxxxxxxxxxxx>, xfs@xxxxxxxxxxx > > Sent: Thursday, September 8, 2016 2:01:23 PM > > Subject: Re: xfs_file_splice_read: possible circular locking dependency detected > > > > On Thu, Sep 8, 2016 at 8:29 AM, CAI Qian <caiqian@xxxxxxxxxx> wrote: > > > Right. FYI, revert the commit below fixes the regression, > > > > > > 8d02076 : ->splice_write() via ->write_iter() > > > > I guess you didn't actually revert that, because so much else has > > changed. So you just tested the pre- and post- state of that commit? > Right, I just reverted that commit while that one is as a HEAD. It is > not going to be a straight-forward revert. There have had a few commits > on the top already, so there will be some additional work to bake a proper > revert to the current origin HEAD. > > Though, Everything else looks straigtforward (PAGE_CACHE_* conversion, > inode_lock* conversion, file_remove_privs() converstion). It seems only > tricky thing is that generic_write_sync() starts to use struct kiocb * > instead of struct file *, so generic_file_splice_write() and probably > xfs_file_splice_write() need to change to use kiocb as well. Don't bother. You'll just hit a different lockdep issue - a locking order problem on the write side. I tried to get that fixed years ago: https://lkml.org/lkml/2011/7/18/4 http://oss.sgi.com/archives/xfs/2011-08/msg00122.html http://oss.sgi.com/archives/xfs/2012-11/msg00671.html That specific problem was fixed by the above write_iter infrastructure fixes, but introduced the read side problem. i.e. splice has /always/ had locking order issues that XFS exposed. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
