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6#include <linux/kernel.h>
7#include <linux/mm.h>
8#include <linux/fs.h>
9#include <linux/writeback.h>
10#include <linux/sysctl.h>
11#include <linux/gfp.h>
12#include "internal.h"
13
14
15int sysctl_drop_caches;
16
17static void drop_pagecache_sb(struct super_block *sb, void *unused)
18{
19 struct inode *inode, *toput_inode = NULL;
20
21 spin_lock(&sb->s_inode_list_lock);
22 list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
23 spin_lock(&inode->i_lock);
24
25
26
27
28
29 if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
30 (inode->i_mapping->nrpages == 0 && !need_resched())) {
31 spin_unlock(&inode->i_lock);
32 continue;
33 }
34 __iget(inode);
35 spin_unlock(&inode->i_lock);
36 spin_unlock(&sb->s_inode_list_lock);
37
38 invalidate_mapping_pages(inode->i_mapping, 0, -1);
39 iput(toput_inode);
40 toput_inode = inode;
41
42 cond_resched();
43 spin_lock(&sb->s_inode_list_lock);
44 }
45 spin_unlock(&sb->s_inode_list_lock);
46 iput(toput_inode);
47}
48
49int drop_caches_sysctl_handler(struct ctl_table *table, int write,
50 void *buffer, size_t *length, loff_t *ppos)
51{
52 int ret;
53
54 ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
55 if (ret)
56 return ret;
57 if (write) {
58 static int stfu;
59
60 if (sysctl_drop_caches & 1) {
61 iterate_supers(drop_pagecache_sb, NULL);
62 count_vm_event(DROP_PAGECACHE);
63 }
64 if (sysctl_drop_caches & 2) {
65 drop_slab();
66 count_vm_event(DROP_SLAB);
67 }
68 if (!stfu) {
69 pr_info("%s (%d): drop_caches: %d\n",
70 current->comm, task_pid_nr(current),
71 sysctl_drop_caches);
72 }
73 stfu |= sysctl_drop_caches & 4;
74 }
75 return 0;
76}
77