[Cluster-devel] [GFS2 Patch] GFS2: simplify function gfs2_extent_length

[Cluster-devel] [GFS2 Patch] GFS2: simplify function gfs2_extent_length

[Bob Peterson]

Hi,

See description below. :)

Regards,

Bob Peterson
Red Hat File Systems

Signed-off-by: Bob Peterson <rpeterso@redhat.com> 
---
Author: Bob Peterson <rpeterso@redhat.com>
Date:   Wed May 9 14:27:00 2012 -0500

GFS2: simplify function gfs2_extent_length

This patch simplifies function gfs2_extent_length by passing a single
parameter to the function rather than two.

diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index 420bbeb..31c5e81 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -345,8 +345,7 @@ static inline void release_metapath(struct metapath *mp)
 
 /**
  * gfs2_extent_length - Returns length of an extent of blocks
- * @start: Start of the buffer
- * @len: Length of the buffer in bytes
+ * @bh: The buffer header
  * @ptr: Current position in the buffer
  * @limit: Max extent length to return (0 = unlimited)
  * @eob: Set to 1 if we hit "end of block"
@@ -358,9 +357,11 @@ static inline void release_metapath(struct metapath *mp)
  * Returns: The length of the extent (minimum of one block)
  */
 
-static inline unsigned int gfs2_extent_length(void *start, unsigned int len, __be64 *ptr, unsigned limit, int *eob)
+static inline unsigned int gfs2_extent_length(struct buffer_head *bh,
+					      __be64 *ptr, unsigned limit,
+					      int *eob)
 {
-	const __be64 *end = (start + len);
+	const __be64 *end = (const __be64 *)(bh->b_data + bh->b_size);
 	const __be64 *first = ptr;
 	u64 d = be64_to_cpu(*ptr);
 
@@ -475,8 +476,7 @@ static int gfs2_bmap_alloc(struct inode *inode, const sector_t lblock,
 		/* Bottom indirect block exists, find unalloced extent size */
 		ptr = metapointer(end_of_metadata, mp);
 		bh = mp->mp_bh[end_of_metadata];
-		dblks = gfs2_extent_length(bh->b_data, bh->b_size, ptr, maxlen,
-					   &eob);
+		dblks = gfs2_extent_length(bh, ptr, maxlen, &eob);
 		BUG_ON(dblks < 1);
 		state = ALLOC_DATA;
 	} else {
@@ -650,7 +650,7 @@ int gfs2_block_map(struct inode *inode, sector_t lblock,
 		goto do_alloc;
 	map_bh(bh_map, inode->i_sb, be64_to_cpu(*ptr));
 	bh = mp.mp_bh[ip->i_height - 1];
-	len = gfs2_extent_length(bh->b_data, bh->b_size, ptr, maxlen, &eob);
+	len = gfs2_extent_length(bh, ptr, maxlen, &eob);
 	bh_map->b_size = (len << inode->i_blkbits);
 	if (eob)
 		set_buffer_boundary(bh_map);

[Cluster-devel] [GFS2 Patch] GFS2: simplify function gfs2_extent_length

[Steven Whitehouse]

Hi,

On Thu, 2012-05-10 at 08:31 -0400, Bob Peterson wrote:
> Hi,
> 
> See description below. :)
> 
> Regards,
> 
> Bob Peterson
> Red Hat File Systems
> 
> Signed-off-by: Bob Peterson <rpeterso@redhat.com> 
> ---
> Author: Bob Peterson <rpeterso@redhat.com>
> Date:   Wed May 9 14:27:00 2012 -0500
> 
> GFS2: simplify function gfs2_extent_length
> 
> This patch simplifies function gfs2_extent_length by passing a single
> parameter to the function rather than two.
> 
Hmm. I'm not sure this really buys us anything. The function is inline
anyway and it means that it will then be tied to only using buffer heads
whereas before it could potentially have been used for any situation,

Steve.

> diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
> index 420bbeb..31c5e81 100644
> --- a/fs/gfs2/bmap.c
> +++ b/fs/gfs2/bmap.c
> @@ -345,8 +345,7 @@ static inline void release_metapath(struct metapath *mp)
>  
>  /**
>   * gfs2_extent_length - Returns length of an extent of blocks
> - * @start: Start of the buffer
> - * @len: Length of the buffer in bytes
> + * @bh: The buffer header
>   * @ptr: Current position in the buffer
>   * @limit: Max extent length to return (0 = unlimited)
>   * @eob: Set to 1 if we hit "end of block"
> @@ -358,9 +357,11 @@ static inline void release_metapath(struct metapath *mp)
>   * Returns: The length of the extent (minimum of one block)
>   */
>  
> -static inline unsigned int gfs2_extent_length(void *start, unsigned int len, __be64 *ptr, unsigned limit, int *eob)
> +static inline unsigned int gfs2_extent_length(struct buffer_head *bh,
> +					      __be64 *ptr, unsigned limit,
> +					      int *eob)
>  {
> -	const __be64 *end = (start + len);
> +	const __be64 *end = (const __be64 *)(bh->b_data + bh->b_size);
>  	const __be64 *first = ptr;
>  	u64 d = be64_to_cpu(*ptr);
>  
> @@ -475,8 +476,7 @@ static int gfs2_bmap_alloc(struct inode *inode, const sector_t lblock,
>  		/* Bottom indirect block exists, find unalloced extent size */
>  		ptr = metapointer(end_of_metadata, mp);
>  		bh = mp->mp_bh[end_of_metadata];
> -		dblks = gfs2_extent_length(bh->b_data, bh->b_size, ptr, maxlen,
> -					   &eob);
> +		dblks = gfs2_extent_length(bh, ptr, maxlen, &eob);
>  		BUG_ON(dblks < 1);
>  		state = ALLOC_DATA;
>  	} else {
> @@ -650,7 +650,7 @@ int gfs2_block_map(struct inode *inode, sector_t lblock,
>  		goto do_alloc;
>  	map_bh(bh_map, inode->i_sb, be64_to_cpu(*ptr));
>  	bh = mp.mp_bh[ip->i_height - 1];
> -	len = gfs2_extent_length(bh->b_data, bh->b_size, ptr, maxlen, &eob);
> +	len = gfs2_extent_length(bh, ptr, maxlen, &eob);
>  	bh_map->b_size = (len << inode->i_blkbits);
>  	if (eob)
>  		set_buffer_boundary(bh_map);
>