Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost
[linux-2.6-block.git] / fs / drop_caches.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Implement the manual drop-all-pagecache function
4  */
5
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 /* A global variable is a bit ugly, but it keeps the code simple */
15 int sysctl_drop_caches;
16
17 static 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                 if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
25                     (inode->i_mapping->nrpages == 0)) {
26                         spin_unlock(&inode->i_lock);
27                         continue;
28                 }
29                 __iget(inode);
30                 spin_unlock(&inode->i_lock);
31                 spin_unlock(&sb->s_inode_list_lock);
32
33                 invalidate_mapping_pages(inode->i_mapping, 0, -1);
34                 iput(toput_inode);
35                 toput_inode = inode;
36
37                 spin_lock(&sb->s_inode_list_lock);
38         }
39         spin_unlock(&sb->s_inode_list_lock);
40         iput(toput_inode);
41 }
42
43 int drop_caches_sysctl_handler(struct ctl_table *table, int write,
44         void __user *buffer, size_t *length, loff_t *ppos)
45 {
46         int ret;
47
48         ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
49         if (ret)
50                 return ret;
51         if (write) {
52                 static int stfu;
53
54                 if (sysctl_drop_caches & 1) {
55                         iterate_supers(drop_pagecache_sb, NULL);
56                         count_vm_event(DROP_PAGECACHE);
57                 }
58                 if (sysctl_drop_caches & 2) {
59                         drop_slab();
60                         count_vm_event(DROP_SLAB);
61                 }
62                 if (!stfu) {
63                         pr_info("%s (%d): drop_caches: %d\n",
64                                 current->comm, task_pid_nr(current),
65                                 sysctl_drop_caches);
66                 }
67                 stfu |= sysctl_drop_caches & 4;
68         }
69         return 0;
70 }