[Cluster-devel] [PATCH 2/5] GFS2: introduce bi_blocks for optimization

[Bob Peterson]

This patch introduces a new field in the bitmap structure called
bi_blocks. Its purpose is to save us from constantly multiplying
bi_len by the constant GFS2_NBBY. It also paves the way for more
optimization in a future patch.
---
 fs/gfs2/incore.h | 1 +
 fs/gfs2/rgrp.c   | 6 +++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 26aabd7..f1a3243 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -71,6 +71,7 @@ struct gfs2_bitmap {
 	u32 bi_offset;
 	u32 bi_start;
 	u32 bi_len;
+	u32 bi_blocks;
 };
 
 struct gfs2_rgrpd {
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 7a6fa03..7d64a27 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -262,7 +262,7 @@ static int gfs2_rbm_from_block(struct gfs2_rbm *rbm, u64 block)
 	rbm->bi = rbm->rgd->rd_bits;
 	rbm->offset = (u32)(rblock);
 	/* Check if the block is within the first block */
-	if (rbm->offset < rbm->bi->bi_len * GFS2_NBBY)
+	if (rbm->offset < rbm->bi->bi_blocks)
 		return 0;
 
 	/* Adjust for the size diff between gfs2_meta_header and gfs2_rgrp */
@@ -743,18 +743,21 @@ static int compute_bitstructs(struct gfs2_rgrpd *rgd)
 			bi->bi_offset = sizeof(struct gfs2_rgrp);
 			bi->bi_start = 0;
 			bi->bi_len = bytes;
+			bi->bi_blocks = bytes * GFS2_NBBY;
 		/* header block */
 		} else if (x == 0) {
 			bytes = sdp->sd_sb.sb_bsize - sizeof(struct gfs2_rgrp);
 			bi->bi_offset = sizeof(struct gfs2_rgrp);
 			bi->bi_start = 0;
 			bi->bi_len = bytes;
+			bi->bi_blocks = bytes * GFS2_NBBY;
 		/* last block */
 		} else if (x + 1 == length) {
 			bytes = bytes_left;
 			bi->bi_offset = sizeof(struct gfs2_meta_header);
 			bi->bi_start = rgd->rd_bitbytes - bytes_left;
 			bi->bi_len = bytes;
+			bi->bi_blocks = bytes * GFS2_NBBY;
 		/* other blocks */
 		} else {
 			bytes = sdp->sd_sb.sb_bsize -
@@ -762,6 +765,7 @@ static int compute_bitstructs(struct gfs2_rgrpd *rgd)
 			bi->bi_offset = sizeof(struct gfs2_meta_header);
 			bi->bi_start = rgd->rd_bitbytes - bytes_left;
 			bi->bi_len = bytes;
+			bi->bi_blocks = bytes * GFS2_NBBY;
 		}
 
 		bytes_left -= bytes;
-- 
1.8.3.1