On Fri, May 12, 2023 at 10:53:29AM +0800, renlei1@xxxxxxxxxxxxxxx wrote: > Yup, gen is 0 for the inodes created by libxfs, such as rootino, rbmino, rsumino. > but those inodes will never be freed, and gen will always zero. > so I think bypass the verification if gen==0 is still valid. I disagree. Handles have long encoded inode and generation to prevent users from unintentionally modifying a file when the inode number is recycled as a result of an unlink/create cycle. --D > Regards, > Lei > > From: Dave Chinner > Date: 2023-05-12 10:00 > To: Darrick J. Wong > CC: renlei1; linux-xfs; linux-kernel > Subject: Re: [PATCH] xfs: xfs_nfs_get_inode support zero generation > On Thu, May 11, 2023 at 04:22:06PM -0700, Darrick J. Wong wrote: > > On Thu, May 11, 2023 at 06:17:21PM +0800, renlei1@xxxxxxxxxxxxxxx wrote: > > > From: Ren Lei <renlei1@xxxxxxxxxxxxxxx> > > > > > > If generation is zero, bypass the verification of generation number > > > to avoid stale file error. (Be consistent with other fs, such as > > > ext4, fat, jfs, etc.) > > > > What code is affected by the gen==0 handles being rejected? Is there a > > user program or test case where this is required? > > A generation number of 0 is perfectly valid in XFS. We've been > creating them in XFS filesystems since 1993 and never had a problem > with filehandle verification. Indeed, every root inode in every XFS > filesystem ever made will have a generation number of 0. > > Yup, a random XFS filesystem recently made from a current xfsprogs: > > # xfs_db /dev/vdc > xfs_db> sb 0 > xfs_db> a rootino > xfs_db> p core.gen > core.gen = 0 > xfs_db> > > -Dave. > -- > Dave Chinner > david@xxxxxxxxxxxxx >
