On Wed, 2022-08-24 at 07:53 +1000, Dave Chinner wrote: > On Fri, Aug 19, 2022 at 07:56:41AM -0400, Jeff Layton wrote: > > From: Jeff Layton <jlayton@xxxxxxxxxx> > > > > The NFS server and IMA both rely heavily on the i_version counter, but > > it's largely invisible to userland, which makes it difficult to test its > > behavior. This value would also be of use to userland NFS servers, and > > other applications that want a reliable way to know if there was an > > explicit change to an inode since they last checked. > > > > Claim one of the spare fields in struct statx to hold a 64-bit inode > > version attribute. This value must change with any explicit, observeable > > metadata or data change. Note that atime updates are excluded from this, > > unless it is due to an explicit change via utimes or similar mechanism. > > > > When statx requests this attribute on an IS_I_VERSION inode, do an > > inode_query_iversion and fill the result in the field. Also, update the > > test-statx.c program to display the inode version and the mountid. > > > > Cc: David Howells <dhowells@xxxxxxxxxx> > > Cc: Frank Filz <ffilzlnx@xxxxxxxxxxxxxx> > > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> > > NAK. > > THere's no definition of what consitutes an "inode change" and this > exposes internal filesystem implementation details (i.e. on disk > format behaviour) directly to userspace. That means when the > internal filesystem behaviour changes, userspace applications will > see changes in stat->ino_version changes and potentially break them. > > We *need a documented specification* for the behaviour we are exposing to > userspace here, and then individual filesystems needs to opt into > providing this information as they are modified to conform to the > behaviour we are exposing directly to userspsace. > > Jeff - can you please stop posting iversion patches to different > subsystems as individual, unrelated patchsets and start posting all > the changes - statx, ext4, xfs, man pages, etc as a single patchset > so the discussion can be centralised in one place and not spread > over half a dozen disconnected threads? > Sure. Give me a few days and I'll post a more coherent set of patches. Thanks, -- Jeff Layton <jlayton@xxxxxxxxxx>
