Re: [PATCH v3] erofs: add sysfs feature entry for xattr prefixes

[Greg KH]

On Wed, Sep 02, 2026 at 06:53:16PM +0800, Gao Xiang wrote:
> Hi Greg,
> 
> On Wed, Sep 02, 2026 at 07:36:13AM +0200, Greg KH wrote:
> > On Wed, Sep 02, 2026 at 09:50:39AM +0800, Jingbo Xu wrote:
> > > Let /sys/fs/erofs/features/xattr_prefixes advertise that this kernel
> > > supports the EROFS_FEATURE_INCOMPAT_XATTR_PREFIXES on-disk format.
> > > 
> > > Fixes: 6a318ccd7e08 ("erofs: enable long extended attribute name prefixes")
> > > Cc: <stable@xxxxxxxxxxxxxxx> # 6.4+
> > > Reviewed-by: Gao Xiang <xiang@xxxxxxxxxx>
> > > Signed-off-by: Jingbo Xu <jefflexu@xxxxxxxxxxxxxxxxx>
> > > ---
> > > changes since v2:
> > > - add Reviewed-by tag (Gao Xiang)
> > > - update list in Documentation/ABI/testing/sysfs-fs-erofs
> > > (https://sashiko.dev/#/patchset/20260901062243.109172-1-jefflexu%40linux.alibaba.com)
> > > ---
> > >  Documentation/ABI/testing/sysfs-fs-erofs | 2 +-
> > >  fs/erofs/sysfs.c                         | 2 ++
> > >  2 files changed, 3 insertions(+), 1 deletion(-)
> > 
> > Why is adding a new feature a stable thing?
> 
> It's not a new feature (Also, this patch has 3 lines diff):
> This is a bugfix to address the missing part of
> commit 6a318ccd7e08 ("erofs: enable long extended
> attribute name prefixes"") since every on-disk features
> should be shown in `/sys/fs/erofs/features/*` according to
> the definition of:
> 
> What:           /sys/fs/erofs/features/
> Date:           November 2021
> Contact:        "Huang Jianan" <huangjianan@xxxxxxxx>
> Description:    Shows all enabled kernel features.
> ...
> 
> IOWs, this sysfs entry should be part of commit 6a318ccd7e08
> to indicate this feature is supported since Linux 6.4+

Ok, but as this has not been present for a very long time, did anyone
even notice and need this now in stable kernels?  :)

thanks,

greg k-h