From ea09eecf7787d6ad5451caed0a4c6f9cff605304 Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hugh@veritas.com>
Date: Tue, 6 Jan 2009 14:39:54 -0800
Subject: [PATCH] --- yaml --- r: 126227 b: refs/heads/master c:
 20137a490f397d9c01fc9fadd83a8d198bda4477 h: refs/heads/master i:   126225:
 474f109e99d32d4d81f37712c4f47846263a7ab0   126223:
 814b9facc356c98d452e910f1e615178155395b5 v: v3

---
 [refs]                     |  2 +-
 trunk/include/linux/swap.h |  1 +
 trunk/mm/swapfile.c        | 11 +++++++++--
 3 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/[refs] b/[refs]
index 26d453b9b51c..366fc4dd28a9 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 7992fde72ce06c73280a1939b7a1e903bc95ef85
+refs/heads/master: 20137a490f397d9c01fc9fadd83a8d198bda4477
diff --git a/trunk/include/linux/swap.h b/trunk/include/linux/swap.h
index fe79f44c858e..cbf7fbed3dfd 100644
--- a/trunk/include/linux/swap.h
+++ b/trunk/include/linux/swap.h
@@ -122,6 +122,7 @@ enum {
 	SWP_WRITEOK	= (1 << 1),	/* ok to write to this swap?	*/
 	SWP_DISCARDABLE = (1 << 2),	/* blkdev supports discard */
 	SWP_DISCARDING	= (1 << 3),	/* now discarding a free cluster */
+	SWP_SOLIDSTATE	= (1 << 4),	/* blkdev seeks are cheap */
 					/* add others here before... */
 	SWP_SCANNING	= (1 << 8),	/* refcount in scan_swap_map */
 };
diff --git a/trunk/mm/swapfile.c b/trunk/mm/swapfile.c
index ca75b9e7c09f..b0f56603b9be 100644
--- a/trunk/mm/swapfile.c
+++ b/trunk/mm/swapfile.c
@@ -16,6 +16,7 @@
 #include <linux/namei.h>
 #include <linux/shm.h>
 #include <linux/blkdev.h>
+#include <linux/random.h>
 #include <linux/writeback.h>
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
@@ -1806,6 +1807,11 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
 		goto bad_swap;
 	}
 
+	if (blk_queue_nonrot(bdev_get_queue(p->bdev))) {
+		p->flags |= SWP_SOLIDSTATE;
+		srandom32((u32)get_seconds());
+		p->cluster_next = 1 + (random32() % p->highest_bit);
+	}
 	if (discard_swap(p) == 0)
 		p->flags |= SWP_DISCARDABLE;
 
@@ -1822,10 +1828,11 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
 	total_swap_pages += nr_good_pages;
 
 	printk(KERN_INFO "Adding %uk swap on %s.  "
-			"Priority:%d extents:%d across:%lluk%s\n",
+			"Priority:%d extents:%d across:%lluk %s%s\n",
 		nr_good_pages<<(PAGE_SHIFT-10), name, p->prio,
 		nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10),
-		(p->flags & SWP_DISCARDABLE) ? " D" : "");
+		(p->flags & SWP_SOLIDSTATE) ? "SS" : "",
+		(p->flags & SWP_DISCARDABLE) ? "D" : "");
 
 	/* insert swap space into swap_list: */
 	prev = -1;