[Adding fsdevel to cc since this is a filesystems question]
On Fri, Nov 20, 2020 at 04:58:09PM -0800, Randy Dunlap wrote:
> Hi,
>
> I don't know this code, but:
>
> On 11/20/20 4:33 PM, XiaoLi Feng wrote:
> > From: Xiaoli Feng <fengxiaoli0714@xxxxxxxxx>
> >
> > keep attributes and attributes_mask are consistent for
> > STATX_ATTR_DAX.
> > ---
> > fs/stat.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/stat.c b/fs/stat.c
> > index dacecdda2e79..914a61d256b0 100644
> > --- a/fs/stat.c
> > +++ b/fs/stat.c
> > @@ -82,7 +82,7 @@ int vfs_getattr_nosec(const struct path *path, struct kstat *stat,
> >
> > if (IS_DAX(inode))
> > stat->attributes |= STATX_ATTR_DAX;
> > -
> > + stat->attributes_mask |= STATX_ATTR_DAX;
>
> Why shouldn't that be:
>
> if (IS_DAX(inode))
> stat->attributes_mask |= STATX_ATTR_DAX;
>
> or combine them, like this:
>
> if (IS_DAX(inode)) {
> stat->attributes |= STATX_ATTR_DAX;
> stat->attributes_mask |= STATX_ATTR_DAX;
> }
>
>
> and no need to delete that blank line.
Some filesystems could support DAX but not have it enabled for this
particular file, so this won't work.
General question: should filesystems that are /capable/ of DAX signal
this by setting the DAX bit in the attributes mask? Or is this a VFS
feature and hence here is the appropriate place to be setting the mask?
Extra question: should we only set this in the attributes mask if
CONFIG_FS_DAX=y ?
--D
> > if (inode->i_op->getattr)
> > return inode->i_op->getattr(path, stat, request_mask,
> > query_flags);
> >
>
> thanks.
> --
> ~Randy
>
