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>

1 files changed, 5 insertions, 7 deletions

diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 29703dd97dc9..55b3bbaf2f25 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -583,7 +583,7 @@ static int link_dinode(struct gfs2_inode *dip, const struct qstr *name,
                         goto fail_quota_locks;
 
                 error = gfs2_trans_begin(sdp, sdp->sd_max_dirres +
-                                         al->al_rgd->rd_length +
+                                         dip->i_rgd->rd_length +
                                          2 * RES_DINODE +
                                          RES_STATFS + RES_QUOTA, 0);
                 if (error)
@@ -613,8 +613,7 @@ fail_end_trans:
         gfs2_trans_end(sdp);
 
 fail_ipreserv:
-        if (dip->i_alloc->al_rgd)
-                gfs2_inplace_release(dip);
+        gfs2_inplace_release(dip);
 
 fail_quota_locks:
         gfs2_quota_unlock(dip);
@@ -731,8 +730,7 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
                 brelse(bh);
 
         gfs2_trans_end(sdp);
-        if (dip->i_alloc->al_rgd)
-                gfs2_inplace_release(dip);
+        gfs2_inplace_release(dip);
         gfs2_quota_unlock(dip);
         gfs2_alloc_put(dip);
         mark_inode_dirty(inode);
@@ -896,7 +894,7 @@ static int gfs2_link(struct dentry *old_dentry, struct inode *dir,
                         goto out_gunlock_q;
 
                 error = gfs2_trans_begin(sdp, sdp->sd_max_dirres +
-                                         gfs2_rg_blocks(al) +
+                                         gfs2_rg_blocks(dip) +
                                          2 * RES_DINODE + RES_STATFS +
                                          RES_QUOTA, 0);
                 if (error)
@@ -1371,7 +1369,7 @@ static int gfs2_rename(struct inode *odir, struct dentry *odentry,
                         goto out_gunlock_q;
 
                 error = gfs2_trans_begin(sdp, sdp->sd_max_dirres +
-                                         gfs2_rg_blocks(al) +
+                                         gfs2_rg_blocks(ndip) +
                                          4 * RES_DINODE + 4 * RES_LEAF +
                                          RES_STATFS + RES_QUOTA + 4, 0);
                 if (error)