On Tue, Feb 08, 2022 at 08:29:56PM +0200, Mike Rapoport wrote:
> Hi,
>
> On Tue, Jan 18, 2022 at 09:21:13PM +0800, Chao Peng wrote:
> > It maintains a memfile_notifier list in shmem_inode_info structure and
> > implements memfile_pfn_ops callbacks defined by memfile_notifier. It
> > then exposes them to memfile_notifier via
> > shmem_get_memfile_notifier_info.
> >
> > We use SGP_NOALLOC in shmem_get_lock_pfn since the pages should be
> > allocated by userspace for private memory. If there is no pages
> > allocated at the offset then error should be returned so KVM knows that
> > the memory is not private memory.
> >
> > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> > Signed-off-by: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>
> > ---
> > include/linux/shmem_fs.h | 4 ++
> > mm/memfile_notifier.c | 12 +++++-
> > mm/shmem.c | 81 ++++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 96 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
> > index 166158b6e917..461633587eaf 100644
> > --- a/include/linux/shmem_fs.h
> > +++ b/include/linux/shmem_fs.h
> > @@ -9,6 +9,7 @@
> > #include <linux/percpu_counter.h>
> > #include <linux/xattr.h>
> > #include <linux/fs_parser.h>
> > +#include <linux/memfile_notifier.h>
> >
> > /* inode in-kernel data */
> >
> > @@ -24,6 +25,9 @@ struct shmem_inode_info {
> > struct shared_policy policy; /* NUMA memory alloc policy */
> > struct simple_xattrs xattrs; /* list of xattrs */
> > atomic_t stop_eviction; /* hold when working on inode */
> > +#ifdef CONFIG_MEMFILE_NOTIFIER
> > + struct memfile_notifier_list memfile_notifiers;
> > +#endif
> > struct inode vfs_inode;
> > };
> >
> > diff --git a/mm/memfile_notifier.c b/mm/memfile_notifier.c
> > index 8171d4601a04..b4699cbf629e 100644
> > --- a/mm/memfile_notifier.c
> > +++ b/mm/memfile_notifier.c
> > @@ -41,11 +41,21 @@ void memfile_notifier_fallocate(struct memfile_notifier_list *list,
> > srcu_read_unlock(&srcu, id);
> > }
> >
> > +#ifdef CONFIG_SHMEM
> > +extern int shmem_get_memfile_notifier_info(struct inode *inode,
> > + struct memfile_notifier_list **list,
> > + struct memfile_pfn_ops **ops);
> > +#endif
> > +
> > static int memfile_get_notifier_info(struct inode *inode,
> > struct memfile_notifier_list **list,
> > struct memfile_pfn_ops **ops)
> > {
> > - return -EOPNOTSUPP;
> > + int ret = -EOPNOTSUPP;
> > +#ifdef CONFIG_SHMEM
> > + ret = shmem_get_memfile_notifier_info(inode, list, ops);
> > +#endif
>
> This looks backwards. Can we have some register method for memory backing
> store and call it from shmem.c?
Agreed. That would be clearer.
Chao
>
> > + return ret;
> > }
> >
> > int memfile_register_notifier(struct inode *inode,
>
> --
> Sincerely yours,
> Mike.
