lkml.org 
[lkml]   [2016]   [Jul]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: More parallel atomic_open/d_splice_alias fun with NFS and possibly more FSes.
On Tue, Jul 05, 2016 at 01:31:10PM +0100, Al Viro wrote:
> On Tue, Jul 05, 2016 at 02:22:48AM -0400, Oleg Drokin wrote:
>
> > > + if (!(open_flags & O_CREAT) && !d_unhashed(dentry)) {
>
> s/d_unhashed/d_in_lookup/ in that.
>
> > So we come racing here from multiple threads (say 3 or more - we have seen this
> > in the older crash reports, so totally possible)
> >
> > > + d_drop(dentry);
> >
> > One lucky one does this first before the others perform the !d_unhashed check above.
> > This makes the other ones to not enter here.
> >
> > And we are back to the original problem of multiple threads trying to instantiate
> > same dentry as before.
>
> Yep. See above - it should've been using d_in_lookup() in the first place,
> through the entire nfs_atomic_open(). Same in the Lustre part of fixes,
> obviously.

See current #for-linus for hopefully fixed variants (both lustre and nfs)

\
 
 \ /
  Last update: 2016-07-05 16:21    [W:0.089 / U:0.668 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site