GFS2: Speed up starting point selection for block allocation
When setting the starting point for block allocation, there were calls
to both gfs2_rbm_to_block() and gfs2_rbm_from_block() in the common case
of there being an active reservation. The gfs2_rbm_from_block() function
can be quite slow, and since the two conversions were effectively a
no-op, it makes sense to avoid them entirely in this case.
There is no functional change here, but the code should be a bit more
efficient after this patch.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 4f0984a..4d83abd 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -2134,6 +2134,35 @@
}
/**
+ * gfs2_set_alloc_start - Set starting point for block allocation
+ * @rbm: The rbm which will be set to the required location
+ * @ip: The gfs2 inode
+ * @dinode: Flag to say if allocation includes a new inode
+ *
+ * This sets the starting point from the reservation if one is active
+ * otherwise it falls back to guessing a start point based on the
+ * inode's goal block or the last allocation point in the rgrp.
+ */
+
+static void gfs2_set_alloc_start(struct gfs2_rbm *rbm,
+ const struct gfs2_inode *ip, bool dinode)
+{
+ u64 goal;
+
+ if (gfs2_rs_active(ip->i_res)) {
+ *rbm = ip->i_res->rs_rbm;
+ return;
+ }
+
+ if (!dinode && rgrp_contains_block(rbm->rgd, ip->i_goal))
+ goal = ip->i_goal;
+ else
+ goal = rbm->rgd->rd_last_alloc + rbm->rgd->rd_data0;
+
+ gfs2_rbm_from_block(rbm, goal);
+}
+
+/**
* gfs2_alloc_blocks - Allocate one or more blocks of data and/or a dinode
* @ip: the inode to allocate the block for
* @bn: Used to return the starting block number
@@ -2151,22 +2180,14 @@
struct buffer_head *dibh;
struct gfs2_rbm rbm = { .rgd = ip->i_rgd, };
unsigned int ndata;
- u64 goal;
u64 block; /* block, within the file system scope */
int error;
- if (gfs2_rs_active(ip->i_res))
- goal = gfs2_rbm_to_block(&ip->i_res->rs_rbm);
- else if (!dinode && rgrp_contains_block(rbm.rgd, ip->i_goal))
- goal = ip->i_goal;
- else
- goal = rbm.rgd->rd_last_alloc + rbm.rgd->rd_data0;
-
- gfs2_rbm_from_block(&rbm, goal);
+ gfs2_set_alloc_start(&rbm, ip, dinode);
error = gfs2_rbm_find(&rbm, GFS2_BLKST_FREE, 0, ip, false);
if (error == -ENOSPC) {
- gfs2_rbm_from_block(&rbm, goal);
+ gfs2_set_alloc_start(&rbm, ip, dinode);
error = gfs2_rbm_find(&rbm, GFS2_BLKST_FREE, 0, NULL, false);
}