Re: [PATCH 1/2] cifs: store pointer to master tlink in superblock

[Shirish Pargaonkar <shirishpargaonkar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Thu, Oct 28, 2010 at 6:33 AM, Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> Instead of keeping a tag on the master tlink in the tree, just keep a
> pointer to the master in the superblock. That eliminates the need for
> using the radix tree to look up a tagged entry.
>
> Signed-off-by: Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> ---
>  fs/cifs/cifs_fs_sb.h |    2 +-
>  fs/cifs/connect.c    |   18 +++---------------
>  2 files changed, 4 insertions(+), 16 deletions(-)
>
> diff --git a/fs/cifs/cifs_fs_sb.h b/fs/cifs/cifs_fs_sb.h
> index 525ba59..79576da 100644
> --- a/fs/cifs/cifs_fs_sb.h
> +++ b/fs/cifs/cifs_fs_sb.h
> @@ -43,8 +43,8 @@
>
>  struct cifs_sb_info {
>        struct radix_tree_root tlink_tree;
> -#define CIFS_TLINK_MASTER_TAG          0       /* is "master" (mount) tcon */
>        spinlock_t tlink_tree_lock;
> +       struct tcon_link *master_tlink;
>        struct nls_table *local_nls;
>        unsigned int rsize;
>        unsigned int wsize;
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index 469c3dd..364eb96 100644
> --- a/fs/cifs/connect.c
> +++ b/fs/cifs/connect.c
> @@ -2917,11 +2917,11 @@ remote_path_check:
>
>        spin_lock(&cifs_sb->tlink_tree_lock);
>        radix_tree_insert(&cifs_sb->tlink_tree, pSesInfo->linux_uid, tlink);
> -       radix_tree_tag_set(&cifs_sb->tlink_tree, pSesInfo->linux_uid,
> -                          CIFS_TLINK_MASTER_TAG);
>        spin_unlock(&cifs_sb->tlink_tree_lock);
>        radix_tree_preload_end();
>
> +       cifs_sb->master_tlink = tlink;
> +
>        queue_delayed_work(system_nrt_wq, &cifs_sb->prune_tlinks,
>                                TLINK_IDLE_EXPIRE);
>
> @@ -3275,19 +3275,7 @@ out:
>  static struct tcon_link *
>  cifs_sb_master_tlink(struct cifs_sb_info *cifs_sb)
>  {
> -       struct tcon_link *tlink;
> -       unsigned int ret;
> -
> -       spin_lock(&cifs_sb->tlink_tree_lock);
> -       ret = radix_tree_gang_lookup_tag(&cifs_sb->tlink_tree, (void **)&tlink,
> -                                       0, 1, CIFS_TLINK_MASTER_TAG);
> -       spin_unlock(&cifs_sb->tlink_tree_lock);
> -
> -       /* the master tcon should always be present */
> -       if (ret == 0)
> -               BUG();
> -
> -       return tlink;
> +       return cifs_sb->master_tlink;

Wondering whether we need a function just to return master_tlink
within a cifs_sb.
Could the caller(s) of cifs_sb_master_tlink() access master_tlink directly?

>  }
>
>  struct cifsTconInfo *
> --
> 1.7.2.3
>
> --
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