GFS2: Cache the most recently used resource group in the inode
This means that after the initial allocation for any inode, the
last used resource group is cached in the inode for future use.
This drastically reduces the number of lookups of resource
groups in the common case, and this the contention on that
data structure.
The allocation algorithm is the same as previously, except that we
always check to see if the goal block is within the cached rgrp
first before going to the rbtree to look one up.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/trans.h b/fs/gfs2/trans.h
index 980c5c0..f8f101e 100644
--- a/fs/gfs2/trans.h
+++ b/fs/gfs2/trans.h
@@ -28,10 +28,12 @@
/* reserve either the number of blocks to be allocated plus the rg header
* block, or all of the blocks in the rg, whichever is smaller */
-static inline unsigned int gfs2_rg_blocks(const struct gfs2_alloc *al)
+static inline unsigned int gfs2_rg_blocks(const struct gfs2_inode *ip)
{
- return (al->al_requested < al->al_rgd->rd_length)?
- al->al_requested + 1 : al->al_rgd->rd_length;
+ const struct gfs2_alloc *al = ip->i_alloc;
+ if (al->al_requested < ip->i_rgd->rd_length)
+ return al->al_requested + 1;
+ return ip->i_rgd->rd_length;
}
extern int gfs2_trans_begin(struct gfs2_sbd *sdp, unsigned int blocks,