[PATCH 3/6] mm:split the drop cache operation into a function

Put the drop caches operation in a new function and export it, then
wen can reuse it later.

Signed-off-by: Liang Li <>
Cc: Michael S. Tsirkin <>
Cc: Paolo Bonzini <>
Cc: Cornelia Huck <>
Cc: Amit Shah <>
Cc: Alexander Viro <> 
---
 fs/drop_caches.c   | 22 ++++++++++++++--------
 include/linux/mm.h |  1 +
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/fs/drop_caches.c b/fs/drop_caches.c
index d72d52b..977dc71 100644
--- a/fs/drop_caches.c
+++ b/fs/drop_caches.c
@@ -50,14 +50,7 @@ int drop_caches_sysctl_handler(struct ctl_table *table, int write,
 	if (write) {
 		static int stfu;
 
-		if (sysctl_drop_caches & 1) {
-			iterate_supers(drop_pagecache_sb, NULL);
-			count_vm_event(DROP_PAGECACHE);
-		}
-		if (sysctl_drop_caches & 2) {
-			drop_slab();
-			count_vm_event(DROP_SLAB);
-		}
+		drop_caches(sysctl_drop_caches);
 		if (!stfu) {
 			pr_info("%s (%d): drop_caches: %d\n",
 				current->comm, task_pid_nr(current),
@@ -67,3 +60,16 @@ int drop_caches_sysctl_handler(struct ctl_table *table, int write,
 	}
 	return 0;
 }
+
+void drop_caches(int drop_ctl)
+{
+	if (drop_ctl & 1) {
+		iterate_supers(drop_pagecache_sb, NULL);
+		count_vm_event(DROP_PAGECACHE);
+	}
+	if (drop_ctl & 2) {
+		drop_slab();
+		count_vm_event(DROP_SLAB);
+	}
+}
+EXPORT_SYMBOL_GPL(drop_caches);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 5df5feb..e22e315 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2263,6 +2263,7 @@ static inline int in_gate_area(struct mm_struct *mm, unsigned long addr)
 extern int sysctl_drop_caches;
 int drop_caches_sysctl_handler(struct ctl_table *, int,
 					void __user *, size_t *, loff_t *);
+void drop_caches(int drop_ctl);
 #endif
 
 void drop_slab(void);
-- 
1.9.1