[PATCH v4 8/9] mm/swap: Enable swap slots cache usage

[Tim Chen]

Initialize swap slots cache and enable it on swap on.
Drain all swap slots on swap off.

Signed-off-by: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
---
 mm/swapfile.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 3a6cad1..2440cec 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2184,6 +2184,8 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 	spin_unlock(&p->lock);
 	spin_unlock(&swap_lock);
 
+	disable_swap_slots_cache_lock();
+
 	set_current_oom_origin();
 	err = try_to_unuse(p->type, false, 0); /* force unuse all pages */
 	clear_current_oom_origin();
@@ -2191,9 +2193,12 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 	if (err) {
 		/* re-insert swap space back into swap_list */
 		reinsert_swap_info(p);
+		reenable_swap_slots_cache_unlock();
 		goto out_dput;
 	}
 
+	reenable_swap_slots_cache_unlock();
+
 	flush_work(&p->discard_work);
 
 	destroy_swap_extents(p);
@@ -2871,6 +2876,8 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 		putname(name);
 	if (inode && S_ISREG(inode->i_mode))
 		inode_unlock(inode);
+	if (!error)
+		enable_swap_slots_cache();
 	return error;
 }
 
-- 
2.5.5