1 files changed, 68 insertions, 0 deletions

diff --git a/fs/drop_caches.c b/fs/drop_caches.c
new file mode 100644
index 000000000000..4e4762389bdc
--- /dev/null
+++ b/fs/drop_caches.c
@@ -0,0 +1,68 @@
+/*
+ * Implement the manual drop-all-pagecache function
+ */
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/fs.h>
+#include <linux/writeback.h>
+#include <linux/sysctl.h>
+#include <linux/gfp.h>
+
+/* A global variable is a bit ugly, but it keeps the code simple */
+int sysctl_drop_caches;
+
+static void drop_pagecache_sb(struct super_block *sb)
+{
+        struct inode *inode;
+
+        spin_lock(&inode_lock);
+        list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
+                if (inode->i_state & (I_FREEING|I_WILL_FREE))
+                        continue;
+                invalidate_inode_pages(inode->i_mapping);
+        }
+        spin_unlock(&inode_lock);
+}
+
+void drop_pagecache(void)
+{
+        struct super_block *sb;
+
+        spin_lock(&sb_lock);
+restart:
+        list_for_each_entry(sb, &super_blocks, s_list) {
+                sb->s_count++;
+                spin_unlock(&sb_lock);
+                down_read(&sb->s_umount);
+                if (sb->s_root)
+                        drop_pagecache_sb(sb);
+                up_read(&sb->s_umount);
+                spin_lock(&sb_lock);
+                if (__put_super_and_need_restart(sb))
+                        goto restart;
+        }
+        spin_unlock(&sb_lock);
+}
+
+void drop_slab(void)
+{
+        int nr_objects;
+
+        do {
+                nr_objects = shrink_slab(1000, GFP_KERNEL, 1000);
+        } while (nr_objects > 10);
+}
+
+int drop_caches_sysctl_handler(ctl_table *table, int write,
+        struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
+{
+        proc_dointvec_minmax(table, write, file, buffer, length, ppos);
+        if (write) {
+                if (sysctl_drop_caches & 1)
+                        drop_pagecache();
+                if (sysctl_drop_caches & 2)
+                        drop_slab();
+        }
+        return 0;
+}