On Tue, Feb 25, 2020 at 12:28:29PM -0800, Darrick J. Wong wrote: > > diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c > > index 81f2f93caec0..2d5ca13ee9da 100644 > > --- a/fs/xfs/xfs_iops.c > > +++ b/fs/xfs/xfs_iops.c > > @@ -547,9 +547,9 @@ > > stat->uid = inode->i_uid; > > stat->gid = inode->i_gid; > > stat->ino = ip->i_ino; > > - stat->atime = inode->i_atime; > > - stat->mtime = inode->i_mtime; > > - stat->ctime = inode->i_ctime; > > + stat->atime = READ_ONCE(inode->i_atime); > > + stat->mtime = READ_ONCE(inode->i_mtime); > > + stat->ctime = READ_ONCE(inode->i_ctime); > > Seeing as one is supposed to take ILOCK_SHARED before reading inode core > information, why don't we do that here? Is there some huge performance > benefit to be realized from READ_ONCE vs. waiting for the lock that > protects all the writes from each other? Yes, I don't see how READ_ONCE works on a structure. I think you should look into fixing this race in generic_fillattr first, and we then piggy back on that fix in XFS once it has all been sorted out.
