[PATCH 3/4] xfs: simplify xfs_ail_max

[PATCH 3/4] xfs: simplify xfs_ail_max

[Jeff Liu]

From: Jie Liu <jeff.liu@oracle.com>

We have already simplified xfs_ail_min() with a new list helper, i.e,
list_first_entry_or_null(), but xfs_ail_max() still remains as same
as there is no corresponding list helper we can use for now.  It's
fairly easy to simulate the list behavior of getting the last item
in the AIL, therefore we can simplify xfs_ail_max() and move it to
the header file to make this pair of AIL routines looks symmetrical.

Signed-off-by: Jie Liu <jeff.liu@oracle.com>
---
 fs/xfs/xfs_trans_ail.c  | 14 --------------
 fs/xfs/xfs_trans_priv.h | 13 +++++++++++++
 2 files changed, 13 insertions(+), 14 deletions(-)

diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c
index a728735..af605d0 100644
--- a/fs/xfs/xfs_trans_ail.c
+++ b/fs/xfs/xfs_trans_ail.c
@@ -62,20 +62,6 @@ xfs_ail_check(
 #endif /* DEBUG */
 
 /*
- * Return a pointer to the last item in the AIL.  If the AIL is empty, then
- * return NULL.
- */
-static xfs_log_item_t *
-xfs_ail_max(
-	struct xfs_ail  *ailp)
-{
-	if (list_empty(&ailp->xa_ail))
-		return NULL;
-
-	return list_entry(ailp->xa_ail.prev, xfs_log_item_t, li_ail);
-}
-
-/*
  * Return a pointer to the item which follows the given item in the AIL.  If
  * the given item is the last item in the list, then return NULL.
  */
diff --git a/fs/xfs/xfs_trans_priv.h b/fs/xfs/xfs_trans_priv.h
index 12e86af..c564e94 100644
--- a/fs/xfs/xfs_trans_priv.h
+++ b/fs/xfs/xfs_trans_priv.h
@@ -97,6 +97,19 @@ xfs_ail_min(
 					li_ail);
 }
 
+/*
+ * Return a pointer to the last item in the AIL.  If the AIL is empty, then
+ * return NULL.
+ */
+static inline struct xfs_log_item *
+xfs_ail_max(
+	struct xfs_ail  *ailp)
+{
+	return list_empty(&ailp->xa_ail) ? NULL :
+		list_last_entry(&ailp->xa_ail, struct xfs_log_item, li_ail);
+}
+
+
 static inline void
 xfs_trans_ail_update(
 	struct xfs_ail		*ailp,
-- 
1.8.3.2

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Re: [PATCH 3/4] xfs: simplify xfs_ail_max

[Christoph Hellwig]

On Tue, Dec 24, 2013 at 08:48:26PM +0800, Jeff Liu wrote:
> From: Jie Liu <jeff.liu@oracle.com>
> 
> We have already simplified xfs_ail_min() with a new list helper, i.e,
> list_first_entry_or_null(), but xfs_ail_max() still remains as same
> as there is no corresponding list helper we can use for now.  It's
> fairly easy to simulate the list behavior of getting the last item
> in the AIL, therefore we can simplify xfs_ail_max() and move it to
> the header file to make this pair of AIL routines looks symmetrical.

The usageof list_last_entry is fine with me, as is making it inline.
But I think using the explicit if is a lot more readable than the ? :
expression.

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Re: [PATCH 3/4] xfs: simplify xfs_ail_max

[Jeff Liu]

On 12/26 2013 18:07 PM, Christoph Hellwig wrote:
> On Tue, Dec 24, 2013 at 08:48:26PM +0800, Jeff Liu wrote:
>> From: Jie Liu <jeff.liu@oracle.com>
>>
>> We have already simplified xfs_ail_min() with a new list helper, i.e,
>> list_first_entry_or_null(), but xfs_ail_max() still remains as same
>> as there is no corresponding list helper we can use for now.  It's
>> fairly easy to simulate the list behavior of getting the last item
>> in the AIL, therefore we can simplify xfs_ail_max() and move it to
>> the header file to make this pair of AIL routines looks symmetrical.
> 
> The usageof list_last_entry is fine with me, as is making it inline.
> But I think using the explicit if is a lot more readable than the ? :
> expression.
Sounds sensible to me, will take care of it.

Thanks,
-Jeff

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Re: [PATCH 3/4] xfs: simplify xfs_ail_max

[Mark Tinguely]

On 12/24/13 06:48, Jeff Liu wrote:
> From: Jie Liu<jeff.liu@oracle.com>
>
> We have already simplified xfs_ail_min() with a new list helper, i.e,
> list_first_entry_or_null(), but xfs_ail_max() still remains as same
> as there is no corresponding list helper we can use for now.  It's
> fairly easy to simulate the list behavior of getting the last item
> in the AIL, therefore we can simplify xfs_ail_max() and move it to
> the header file to make this pair of AIL routines looks symmetrical.
>
> Signed-off-by: Jie Liu<jeff.liu@oracle.com>
> ---

> +/*
> + * Return a pointer to the last item in the AIL.  If the AIL is empty, then
> + * return NULL.
> + */
> +static inline struct xfs_log_item *
> +xfs_ail_max(
> +	struct xfs_ail  *ailp)
> +{
> +	return list_empty(&ailp->xa_ail) ? NULL :
> +		list_last_entry(&ailp->xa_ail, struct xfs_log_item, li_ail);
> +}
> +
> +
>   static inline void
>   xfs_trans_ail_update(
>   	struct xfs_ail		*ailp,

Looks good.

Reviewed-by: Mark Tinguely <tinguely@sgi.com>

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