Root/fs/drop_caches.c

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}
68

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