cifs: fix reconnect on smb3 mount types

cifs.ko defines two file system types: cifs & smb3, and
__cifs_get_super() was not including smb3 file system type when
looking up superblocks, therefore failing to reconnect tcons in
cifs_tree_connect().

Fix this by calling iterate_supers_type() on both file system types.

Link: https://lore.kernel.org/r/CAFrh3J9soC36+BVuwHB=g9z_KB5Og2+p2_W+BBoBOZveErz14w@mail.gmail.com
Reported-by: Satadru Pramanik <satadru@gmail.com>
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
---
 fs/cifs/cifsfs.c |  2 +-
 fs/cifs/cifsfs.h |  2 +-
 fs/cifs/misc.c   | 27 ++++++++++++++++-----------
 3 files changed, 18 insertions(+), 13 deletions(-)

added cc:stable and tested-by and put updated patch in cifs-2.6.git for-next

On Sun, Jun 5, 2022 at 5:54 PM Paulo Alcantara <pc@cjr.nz> wrote:
>
> cifs.ko defines two file system types: cifs & smb3, and
> __cifs_get_super() was not including smb3 file system type when
> looking up superblocks, therefore failing to reconnect tcons in
> cifs_tree_connect().
>
> Fix this by calling iterate_supers_type() on both file system types.
>
> Link: https://lore.kernel.org/r/CAFrh3J9soC36+BVuwHB=g9z_KB5Og2+p2_W+BBoBOZveErz14w@mail.gmail.com
> Reported-by: Satadru Pramanik <satadru@gmail.com>
> Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
> ---
>  fs/cifs/cifsfs.c |  2 +-
>  fs/cifs/cifsfs.h |  2 +-
>  fs/cifs/misc.c   | 27 ++++++++++++++++-----------
>  3 files changed, 18 insertions(+), 13 deletions(-)
>
> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> index 12c872800326..325423180fd2 100644
> --- a/fs/cifs/cifsfs.c
> +++ b/fs/cifs/cifsfs.c
> @@ -1086,7 +1086,7 @@ struct file_system_type cifs_fs_type = {
>  };
>  MODULE_ALIAS_FS("cifs");
>
> -static struct file_system_type smb3_fs_type = {
> +struct file_system_type smb3_fs_type = {
>         .owner = THIS_MODULE,
>         .name = "smb3",
>         .init_fs_context = smb3_init_fs_context,
> diff --git a/fs/cifs/cifsfs.h b/fs/cifs/cifsfs.h
> index dd7e070ca243..b17be47a8e59 100644
> --- a/fs/cifs/cifsfs.h
> +++ b/fs/cifs/cifsfs.h
> @@ -38,7 +38,7 @@ static inline unsigned long cifs_get_time(struct dentry *dentry)
>         return (unsigned long) dentry->d_fsdata;
>  }
>
> -extern struct file_system_type cifs_fs_type;
> +extern struct file_system_type cifs_fs_type, smb3_fs_type;
>  extern const struct address_space_operations cifs_addr_ops;
>  extern const struct address_space_operations cifs_addr_ops_smallbuf;
>
> diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
> index 35962a1a23b9..8e67a2d406ab 100644
> --- a/fs/cifs/misc.c
> +++ b/fs/cifs/misc.c
> @@ -1211,18 +1211,23 @@ static struct super_block *__cifs_get_super(void (*f)(struct super_block *, void
>                 .data = data,
>                 .sb = NULL,
>         };
> +       struct file_system_type **fs_type = (struct file_system_type *[]) {
> +               &cifs_fs_type, &smb3_fs_type, NULL,
> +       };
>
> -       iterate_supers_type(&cifs_fs_type, f, &sd);
> -
> -       if (!sd.sb)
> -               return ERR_PTR(-EINVAL);
> -       /*
> -        * Grab an active reference in order to prevent automounts (DFS links)
> -        * of expiring and then freeing up our cifs superblock pointer while
> -        * we're doing failover.
> -        */
> -       cifs_sb_active(sd.sb);
> -       return sd.sb;
> +       for (; *fs_type; fs_type++) {
> +               iterate_supers_type(*fs_type, f, &sd);
> +               if (sd.sb) {
> +                       /*
> +                        * Grab an active reference in order to prevent automounts (DFS links)
> +                        * of expiring and then freeing up our cifs superblock pointer while
> +                        * we're doing failover.
> +                        */
> +                       cifs_sb_active(sd.sb);
> +                       return sd.sb;
> +               }
> +       }
> +       return ERR_PTR(-EINVAL);
>  }
>
>  static void __cifs_put_super(struct super_block *sb)
> --
> 2.36.1
>