On Sat, Nov 09, 2024 at 08:21:24AM -0800, Darrick J. Wong wrote:
> On Sat, Nov 09, 2024 at 03:38:55PM +0800, Long Li wrote:
> >
> > Friendly Ping ...
>
> Sorry about that, I missed this one.
>
> > On Mon, Oct 21, 2024 at 09:25:49AM +0800, Long Li wrote:
> > > Compat features are new features that older kernels can safely ignore,
> > > allowing read-write mounts without issues. The current sb write validation
> > > implementation returns -EFSCORRUPTED for unknown compat features,
> > > preventing filesystem write operations and contradicting the feature's
> > > definition.
> > >
> > > Additionally, if the mounted image is unclean, the log recovery may need
> > > to write to the superblock. Returning an error for unknown compat features
> > > during sb write validation can cause mount failures.
> > >
> > > Although XFS currently does not use compat feature flags, this issue
> > > affects current kernels' ability to mount images that may use compat
> > > feature flags in the future.
> > >
> > > Since superblock read validation already warns about unknown compat
> > > features, it's unnecessary to repeat this warning during write validation.
> > > Therefore, the relevant code in write validation is being removed.
> > >
>
> You might want to add this so it actually gets backported:
>
> Cc: <stable@xxxxxxxxxxxxxxx> # v4.19
>
Thanks for your review, indeed, it should backport to v4.19+.
> > > Fixes: 9e037cb7972f ("xfs: check for unknown v5 feature bits in superblock write verifier")
> > > Signed-off-by: Long Li <leo.lilong@xxxxxxxxxx>
>
> Makes sense, so
> Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
>
> --D
>
> > > ---
> > > fs/xfs/libxfs/xfs_sb.c | 7 -------
> > > 1 file changed, 7 deletions(-)
> > >
> > > diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
> > > index d95409f3cba6..02ebcbc4882f 100644
> > > --- a/fs/xfs/libxfs/xfs_sb.c
> > > +++ b/fs/xfs/libxfs/xfs_sb.c
> > > @@ -297,13 +297,6 @@ xfs_validate_sb_write(
> > > * the kernel cannot support since we checked for unsupported bits in
> > > * the read verifier, which means that memory is corrupt.
> > > */
> > > - if (xfs_sb_has_compat_feature(sbp, XFS_SB_FEAT_COMPAT_UNKNOWN)) {
> > > - xfs_warn(mp,
> > > -"Corruption detected in superblock compatible features (0x%x)!",
> > > - (sbp->sb_features_compat & XFS_SB_FEAT_COMPAT_UNKNOWN));
> > > - return -EFSCORRUPTED;
> > > - }
> > > -
> > > if (!xfs_is_readonly(mp) &&
> > > xfs_sb_has_ro_compat_feature(sbp, XFS_SB_FEAT_RO_COMPAT_UNKNOWN)) {
> > > xfs_alert(mp,
> > > --
> > > 2.39.2
> > >
> >
>
