[PATCH] Btrfs: Remove useless condition

[PATCH] Btrfs: Remove useless condition

[Jaswinder Singh Rajput]

if (ret) is useless as it will be never NULL as in previous statement
we are setting ret = prev for !ret

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Chris Mason <chris.mason@oracle.com>
---
 fs/btrfs/ordered-data.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index e56c72b..7b04008 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -154,8 +154,7 @@ static inline struct rb_node *tree_search(struct btrfs_ordered_inode_tree *tree,
 	ret = __tree_search(root, file_offset, &prev);
 	if (!ret)
 		ret = prev;
-	if (ret)
-		tree->last = ret;
+	tree->last = ret;
 	return ret;
 }
 
-- 
1.7.2.2

Re: [PATCH] Btrfs: Remove useless condition

[Johannes Weiner]

On Sun, Sep 12, 2010 at 04:32:20PM +0530, Jaswinder Singh Rajput wrote:
> 
> if (ret) is useless as it will be never NULL as in previous statement
> we are setting ret = prev for !ret

If there is no match and no extent below the given file offset, `prev'
will be NULL as well, no?

So the check is not useless, it prevents throwing out a cached success
in case of a lookup failure.

> Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
> Cc: Chris Mason <chris.mason@oracle.com>
> ---
>  fs/btrfs/ordered-data.c |    3 +--
>  1 files changed, 1 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
> index e56c72b..7b04008 100644
> --- a/fs/btrfs/ordered-data.c
> +++ b/fs/btrfs/ordered-data.c
> @@ -154,8 +154,7 @@ static inline struct rb_node *tree_search(struct btrfs_ordered_inode_tree *tree,
>  	ret = __tree_search(root, file_offset, &prev);
>  	if (!ret)
>  		ret = prev;
> -	if (ret)
> -		tree->last = ret;
> +	tree->last = ret;
>  	return ret;
>  }
>  
> -- 
> 1.7.2.2
> 
> 
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
> 

Re: [PATCH] Btrfs: Remove useless condition

[Jaswinder Singh Rajput]

Hello,

On Sun, Sep 12, 2010 at 5:59 PM, Johannes Weiner <hannes@cmpxchg.org> wrote:
> On Sun, Sep 12, 2010 at 04:32:20PM +0530, Jaswinder Singh Rajput wrote:
>>
>> if (ret) is useless as it will be never NULL as in previous statement
>> we are setting ret = prev for !ret
>
> If there is no match and no extent below the given file offset, `prev'
> will be NULL as well, no?
>
> So the check is not useless, it prevents throwing out a cached success
> in case of a lookup failure.
>

Got it !!

Thanks,
--
Jaswinder Singh.

Re: [PATCH] Btrfs: Remove useless condition

[Mike Fedyk]

On Sun, Sep 12, 2010 at 6:56 AM, Jaswinder Singh Rajput
<jaswinderlinux@gmail.com> wrote:
> Hello,
>
> On Sun, Sep 12, 2010 at 5:59 PM, Johannes Weiner <hannes@cmpxchg.org> wrote:
>> On Sun, Sep 12, 2010 at 04:32:20PM +0530, Jaswinder Singh Rajput wrote:
>>>
>>> if (ret) is useless as it will be never NULL as in previous statement
>>> we are setting ret = prev for !ret
>>
>> If there is no match and no extent below the given file offset, `prev'
>> will be NULL as well, no?
>>
>> So the check is not useless, it prevents throwing out a cached success
>> in case of a lookup failure.
>>
>
> Got it !!
>

Wouldn't it be clearer and easier to read if prev was checked directly
instead of checking ret after it becomes the same as prev?