Re: [PATCH 6/7] cifs: Fix retrieval of DFS referrals in cifs_mount()

[Steve French <smfrench@gmail.com>]

merged into cifs-2.6.git for-next

On Fri, Nov 22, 2019 at 9:31 AM Paulo Alcantara (SUSE) <pc@cjr.nz> wrote:
>
> Make sure that DFS referrals are sent to newly resolved root targets
> as in a multi tier DFS setup.
>
> Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
> Link: https://lkml.kernel.org/r/05aa2995-e85e-0ff4-d003-5bb08bd17a22@canonical.com
> Cc: stable@vger.kernel.org
> Tested-by: Matthew Ruffell <matthew.ruffell@canonical.com>
> ---
>  fs/cifs/connect.c | 32 ++++++++++++++++++++++----------
>  1 file changed, 22 insertions(+), 10 deletions(-)
>
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index 668d477cc9c7..86d98d73749d 100644
> --- a/fs/cifs/connect.c
> +++ b/fs/cifs/connect.c
> @@ -4776,6 +4776,17 @@ static int is_path_remote(struct cifs_sb_info *cifs_sb, struct smb_vol *vol,
>  }
>
>  #ifdef CONFIG_CIFS_DFS_UPCALL
> +static inline void set_root_tcon(struct cifs_sb_info *cifs_sb,
> +                                struct cifs_tcon *tcon,
> +                                struct cifs_tcon **root)
> +{
> +       spin_lock(&cifs_tcp_ses_lock);
> +       tcon->tc_count++;
> +       tcon->remap = cifs_remap(cifs_sb);
> +       spin_unlock(&cifs_tcp_ses_lock);
> +       *root = tcon;
> +}
> +
>  int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
>  {
>         int rc = 0;
> @@ -4877,18 +4888,10 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
>         /* Cache out resolved root server */
>         (void)dfs_cache_find(xid, ses, cifs_sb->local_nls, cifs_remap(cifs_sb),
>                              root_path + 1, NULL, NULL);
> -       /*
> -        * Save root tcon for additional DFS requests to update or create a new
> -        * DFS cache entry, or even perform DFS failover.
> -        */
> -       spin_lock(&cifs_tcp_ses_lock);
> -       tcon->tc_count++;
> -       tcon->dfs_path = root_path;
> +       kfree(root_path);
>         root_path = NULL;
> -       tcon->remap = cifs_remap(cifs_sb);
> -       spin_unlock(&cifs_tcp_ses_lock);
>
> -       root_tcon = tcon;
> +       set_root_tcon(cifs_sb, tcon, &root_tcon);
>
>         for (count = 1; ;) {
>                 if (!rc && tcon) {
> @@ -4925,6 +4928,15 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
>                         mount_put_conns(cifs_sb, xid, server, ses, tcon);
>                         rc = mount_get_conns(vol, cifs_sb, &xid, &server, &ses,
>                                              &tcon);
> +                       /*
> +                        * Ensure that DFS referrals go through new root server.
> +                        */
> +                       if (!rc && tcon &&
> +                           (tcon->share_flags & (SHI1005_FLAGS_DFS |
> +                                                 SHI1005_FLAGS_DFS_ROOT))) {
> +                               cifs_put_tcon(root_tcon);
> +                               set_root_tcon(cifs_sb, tcon, &root_tcon);
> +                       }
>                 }
>                 if (rc) {
>                         if (rc == -EACCES || rc == -EOPNOTSUPP)
> --
> 2.24.0
>


-- 
Thanks,

Steve