[Ocfs2-devel] [PATCH 3/3] Add inode stealing for ocfs2_reserve_new_inode.V2

[Mark Fasheh]

On Thu, Feb 28, 2008 at 03:00:26PM +0800, tao.ma wrote:
> Add inode stealing for ocfs2_reserve_new_inode. Now the whole process is:
> 1. Allocate from its own inode_alloc:000X
>    1) If we can reserve, OK.
>    2) If fails, try to allocate a large chunk and reserve once again.
> 2. If 1 fails, try to allocate from the ocfs2_super->inode_steal_slot.
>    This time, Just try to reserve, we don't go for global_bitmap if
>    this inode also can't allocate the inode.
> 3. If 2 fails, try the node next until we reach that steal slot again.
> 
> ocfs2_super->inode_steal_slot is initalized as the node next to our own
> slot. And once the inode stealing successes, we will refresh it with
> the slot we steal inode from.

> It will also be reinitalized when the local
> truncate log or local alloc recovery is flushed in which case the global
> bitmap may be refreshed.

How about when we free an inode from our slots allocator?


> diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
> index 6546cef..75b7fe0 100644
> --- a/fs/ocfs2/ocfs2.h
> +++ b/fs/ocfs2/ocfs2.h
> @@ -206,11 +206,13 @@ struct ocfs2_super
>  	u32 s_feature_incompat;
>  	u32 s_feature_ro_compat;
>  
> -	/* Protects s_next_generaion, osb_flags. Could protect more on
> -	 * osb as it's very short lived. */
> +	/* Protects s_next_generation, osb_flags and inode_steal_slot.
> +	 * Could protect more on osb as it's very short lived.
> +	 */
>  	spinlock_t osb_lock;
>  	u32 s_next_generation;
>  	unsigned long osb_flags;
> +	s16 inode_steal_slot;

Please prefix this with "s_" or "osb_".


>  	unsigned long s_mount_opt;
>  	unsigned int s_atime_quantum;
> @@ -522,6 +524,36 @@ static inline unsigned int ocfs2_pages_per_cluster(struct super_block *sb)
>  	return pages_per_cluster;
>  }
 
> +static inline void ocfs2_init_inode_steal_slot(struct ocfs2_super *osb)
> +{
> +	BUG_ON(osb->slot_num == OCFS2_INVALID_SLOT);
> +
> +	spin_lock(&osb->osb_lock);
> +	osb->inode_steal_slot = osb->slot_num + 1;
> +	if (osb->inode_steal_slot == osb->max_slots)
> +		osb->inode_steal_slot = 0;
> +	spin_unlock(&osb->osb_lock);
> +}

We probably don't want to inline this.


>  int ocfs2_reserve_new_inode(struct ocfs2_super *osb,
>  			    struct ocfs2_alloc_context **ac)
>  {
> @@ -542,6 +577,17 @@ int ocfs2_reserve_new_inode(struct ocfs2_super *osb,
>  	status = ocfs2_reserve_suballoc_bits(osb, *ac,
>  					     INODE_ALLOC_SYSTEM_INODE,
>  					     osb->slot_num, ALLOC_NEW_GROUP);
> +	if (status >= 0) {
> +		status = 0;
> +		goto bail;
> +	} else if (status < 0 && status != -ENOSPC) {
> +		mlog_errno(status);
> +		goto bail;
> +	}
> +
> +	ocfs2_free_ac_resource(*ac);
> +
> +	status = ocfs2_steal_inode_from_other_nodes(osb, *ac);

Does this mean we always search our own first, even if we know it's not
likely to have anything in it? Wouldn't it be better to ignore once it's
full until we get to one of the spots where you've inserted a call to
ocfs2_init_inode_steal_slot)?
	--Mark

--
Mark Fasheh
Principal Software Developer, Oracle
mark.fasheh at oracle.com