[Linux-cachefs] [PATCH] cifs: wait for tcon resource_id before getting fscache super

[Jeff Layton]

On Fri, 2021-12-03 at 14:52 +0530, Shyam Prasad N wrote:
> The logic for initializing tcon->resource_id is done inside
> cifs_root_iget. fscache super cookie relies on this for aux
> data. So we need to push the fscache initialization to this
> later point during mount.
> 
> Signed-off-by: Shyam Prasad N <sprasad at microsoft.com>
> ---
>  fs/cifs/connect.c | 6 ------
>  fs/cifs/fscache.c | 2 +-
>  fs/cifs/inode.c   | 7 +++++++
>  3 files changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index 6b705026da1a3..eee994b0925ff 100644
> --- a/fs/cifs/connect.c
> +++ b/fs/cifs/connect.c
> @@ -3046,12 +3046,6 @@ static int mount_get_conns(struct mount_ctx *mnt_ctx)
>   cifs_dbg(VFS, "read only mount of RW share\n");
>   /* no need to log a RW mount of a typical RW share */
>   }
> - /*
> - * The cookie is initialized from volume info returned above.
> - * Inside cifs_fscache_get_super_cookie it checks
> - * that we do not get super cookie twice.
> - */
> - cifs_fscache_get_super_cookie(tcon);
>   }
> 
>   /*
> diff --git a/fs/cifs/fscache.c b/fs/cifs/fscache.c
> index 7e409a38a2d7c..f4da693760c11 100644
> --- a/fs/cifs/fscache.c
> +++ b/fs/cifs/fscache.c
> @@ -92,7 +92,7 @@ void cifs_fscache_get_super_cookie(struct cifs_tcon *tcon)
>   * In the future, as we integrate with newer fscache features,
>   * we may want to instead add a check if cookie has changed
>   */
> - if (tcon->fscache == NULL)
> + if (tcon->fscache)
>   return;
> 

Ouch! Does the above mean that fscache on cifs is just plain broken at
the moment? If this is the routine that sets the tcon cookie, then it
looks like it just never gets set?

>   sharename = extract_sharename(tcon->treeName);
> diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
> index 82848412ad852..96d083db17372 100644
> --- a/fs/cifs/inode.c
> +++ b/fs/cifs/inode.c
> @@ -1376,6 +1376,13 @@ struct inode *cifs_root_iget(struct super_block *sb)
>   inode = ERR_PTR(rc);
>   }
> 
> + /*
> + * The cookie is initialized from volume info returned above.
> + * Inside cifs_fscache_get_super_cookie it checks
> + * that we do not get super cookie twice.
> + */
> + cifs_fscache_get_super_cookie(tcon);
> +
>  out:
>   kfree(path);
>   free_xid(xid);
> 

-- 
Jeff Layton <jlayton at redhat.com>