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1/*
2 * Implement the manual drop-all-pagecache function
3 */
4
5#include <linux/kernel.h>
6#include <linux/mm.h>
7#include <linux/fs.h>
8#include <linux/writeback.h>
9#include <linux/sysctl.h>
10#include <linux/gfp.h>
11#include "internal.h"
12
13/* A global variable is a bit ugly, but it keeps the code simple */
14int sysctl_drop_caches;
15
16static void drop_pagecache_sb(struct super_block *sb, void *unused)
17{
18 struct inode *inode, *toput_inode = NULL;
19
20 spin_lock(&inode_sb_list_lock);
21 list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
22 spin_lock(&inode->i_lock);
23 if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
24 (inode->i_mapping->nrpages == 0)) {
25 spin_unlock(&inode->i_lock);
26 continue;
27 }
28 __iget(inode);
29 spin_unlock(&inode->i_lock);
30 spin_unlock(&inode_sb_list_lock);
31 invalidate_mapping_pages(inode->i_mapping, 0, -1);
32 iput(toput_inode);
33 toput_inode = inode;
34 spin_lock(&inode_sb_list_lock);
35 }
36 spin_unlock(&inode_sb_list_lock);
37 iput(toput_inode);
38}
39
40static void drop_slab(void)
41{
42 int nr_objects;
43 struct shrink_control shrink = {
44 .gfp_mask = GFP_KERNEL,
45 };
46
47 do {
48 nr_objects = shrink_slab(&shrink, 1000, 1000);
49 } while (nr_objects > 10);
50}
51
52int drop_caches_sysctl_handler(ctl_table *table, int write,
53 void __user *buffer, size_t *length, loff_t *ppos)
54{
55 int ret;
56
57 ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
58 if (ret)
59 return ret;
60 if (write) {
61 if (sysctl_drop_caches & 1)
62 iterate_supers(drop_pagecache_sb, NULL);
63 if (sysctl_drop_caches & 2)
64 drop_slab();
65 }
66 return 0;
67}