md: Binary search in linear raid

Replace the linear search with binary search in which_dev.

Signed-off-by: Sandeep K Sinha <sandeepksinha@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 17 insertions, 5 deletions

diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index 529a3d37e3fe..9b02a73fbc6b 100644
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -27,14 +27,26 @@
  */
 static inline dev_info_t *which_dev(mddev_t *mddev, sector_t sector)
 {
-        dev_info_t *hash;
+        int lo, mid, hi;
         linear_conf_t *conf = mddev->private;
 
-        hash = conf->disks;
+        lo = 0;
+        hi = mddev->raid_disks - 1;
 
-        while (sector >= hash->end_sector)
-                hash++;
-        return hash;
+        /*
+         * Binary Search
+         */
+
+        while (hi > lo) {
+
+                mid = (hi + lo) / 2;
+                if (sector < conf->disks[mid].end_sector)
+                        hi = mid;
+                else
+                        lo = mid + 1;
+        }
+
+        return conf->disks + lo;
 }
 
 /**