Ocfs2 devel - May 2011 - [PATCH 1/2] Ocfs2/move_extents: Avoid doing division in extent moving.

It's not wise enough to do a 64bits division anywhere in kernside, replace
it
with a decent helper or proper shifts.

Signed-off-by: Tristan Ye <tristan.ye at oracle.com>
---
 fs/ocfs2/move_extents.c |   19 +++++++++----------
 1 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/fs/ocfs2/move_extents.c b/fs/ocfs2/move_extents.c
index 4c54884..d184e0b 100644
--- a/fs/ocfs2/move_extents.c
+++ b/fs/ocfs2/move_extents.c
@@ -368,7 +368,7 @@ static int ocfs2_find_victim_alloc_group(struct inode
*inode,
 					 int *vict_bit,
 					 struct buffer_head **ret_bh)
 {
-	int ret, i, blocks_per_unit = 1;
+	int ret, i, bits_per_unit = 0;
 	u64 blkno;
 	char namebuf[40];
 
@@ -398,14 +398,14 @@ static int ocfs2_find_victim_alloc_group(struct inode
*inode,
 	rec = &(cl->cl_recs[0]);
 
 	if (type == GLOBAL_BITMAP_SYSTEM_INODE)
-		blocks_per_unit <<= (osb->s_clustersize_bits -
-						inode->i_sb->s_blocksize_bits);
+		bits_per_unit = osb->s_clustersize_bits -
+					inode->i_sb->s_blocksize_bits;
 	/*
 	 * 'vict_blkno' was out of the valid range.
 	 */
 	if ((vict_blkno < le64_to_cpu(rec->c_blkno)) ||
-	    (vict_blkno >= (le32_to_cpu(ac_dinode->id1.bitmap1.i_total) *
-				blocks_per_unit))) {
+	    (vict_blkno >= (le32_to_cpu(ac_dinode->id1.bitmap1.i_total) <<
+				bits_per_unit))) {
 		ret = -EINVAL;
 		goto out;
 	}
@@ -441,8 +441,8 @@ static int ocfs2_find_victim_alloc_group(struct inode
*inode,
 						le16_to_cpu(bg->bg_bits))) {
 
 				*ret_bh = gd_bh;
-				*vict_bit = (vict_blkno - blkno) /
-							blocks_per_unit;
+				*vict_bit = (vict_blkno - blkno) >>
+							bits_per_unit;
 				mlog(0, "find the victim group: #%llu, "
 				     "total_bits: %u, vict_bit: %u\n",
 				     blkno, le16_to_cpu(bg->bg_bits),
@@ -493,9 +493,8 @@ static int ocfs2_validate_and_adjust_move_goal(struct inode
*inode,
 	/*
 	 * make goal become cluster aligned.
 	 */
-	if (range->me_goal % c_to_b)
-		range->me_goal = range->me_goal / c_to_b * c_to_b;
-
+	range->me_goal = ocfs2_block_to_cluster_start(inode->i_sb,
+						      range->me_goal);
 	/*
 	 * moving goal is not allowd to start with a group desc blok(#0 blk)
 	 * let's compromise to the latter cluster.
-- 
1.5.5

though the goal_to_be_moved will be validated again in following moving,
it's
still a good idea to validate it after adjustment at the very beginning, instead
of validating it before adjustment.

Signed-off-by: Tristan Ye <tristan.ye at oracle.com>
---
 fs/ocfs2/move_extents.c |   26 +++++++++++++-------------
 1 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/fs/ocfs2/move_extents.c b/fs/ocfs2/move_extents.c
index d184e0b..cd94270 100644
--- a/fs/ocfs2/move_extents.c
+++ b/fs/ocfs2/move_extents.c
@@ -472,12 +472,24 @@ static int ocfs2_validate_and_adjust_move_goal(struct
inode *inode,
 	int ret, goal_bit = 0;
 
 	struct buffer_head *gd_bh = NULL;
-	struct ocfs2_group_desc *bg;
+	struct ocfs2_group_desc *bg = NULL;
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 	int c_to_b = 1 << (osb->s_clustersize_bits -
 					inode->i_sb->s_blocksize_bits);
 
 	/*
+	 * make goal become cluster aligned.
+	 */
+	range->me_goal = ocfs2_block_to_cluster_start(inode->i_sb,
+						      range->me_goal);
+	/*
+	 * moving goal is not allowd to start with a group desc blok(#0 blk)
+	 * let's compromise to the latter cluster.
+	 */
+	if (range->me_goal == le64_to_cpu(bg->bg_blkno))
+		range->me_goal += c_to_b;
+
+	/*
 	 * validate goal sits within global_bitmap, and return the victim
 	 * group desc
 	 */
@@ -491,18 +503,6 @@ static int ocfs2_validate_and_adjust_move_goal(struct inode
*inode,
 	bg = (struct ocfs2_group_desc *)gd_bh->b_data;
 
 	/*
-	 * make goal become cluster aligned.
-	 */
-	range->me_goal = ocfs2_block_to_cluster_start(inode->i_sb,
-						      range->me_goal);
-	/*
-	 * moving goal is not allowd to start with a group desc blok(#0 blk)
-	 * let's compromise to the latter cluster.
-	 */
-	if (range->me_goal == le64_to_cpu(bg->bg_blkno))
-		range->me_goal += c_to_b;
-
-	/*
 	 * movement is not gonna cross two groups.
 	 */
 	if ((le16_to_cpu(bg->bg_bits) - goal_bit) * osb->s_clustersize <
-- 
1.5.5