Merge tag 'clk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux
[platform/kernel/linux-starfive.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/pagemap.h>
7 #include <linux/kernel.h>
8 #include <linux/mm.h>
9 #include <linux/fs.h>
10 #include <linux/writeback.h>
11 #include <linux/sysctl.h>
12 #include <linux/gfp.h>
13 #include "internal.h"
14
15 /* A global variable is a bit ugly, but it keeps the code simple */
16 int sysctl_drop_caches;
17
18 static void drop_pagecache_sb(struct super_block *sb, void *unused)
19 {
20         struct inode *inode, *toput_inode = NULL;
21
22         spin_lock(&sb->s_inode_list_lock);
23         list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
24                 spin_lock(&inode->i_lock);
25                 /*
26                  * We must skip inodes in unusual state. We may also skip
27                  * inodes without pages but we deliberately won't in case
28                  * we need to reschedule to avoid softlockups.
29                  */
30                 if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
31                     (mapping_empty(inode->i_mapping) && !need_resched())) {
32                         spin_unlock(&inode->i_lock);
33                         continue;
34                 }
35                 __iget(inode);
36                 spin_unlock(&inode->i_lock);
37                 spin_unlock(&sb->s_inode_list_lock);
38
39                 invalidate_mapping_pages(inode->i_mapping, 0, -1);
40                 iput(toput_inode);
41                 toput_inode = inode;
42
43                 cond_resched();
44                 spin_lock(&sb->s_inode_list_lock);
45         }
46         spin_unlock(&sb->s_inode_list_lock);
47         iput(toput_inode);
48 }
49
50 int drop_caches_sysctl_handler(struct ctl_table *table, int write,
51                 void *buffer, size_t *length, loff_t *ppos)
52 {
53         int ret;
54
55         ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
56         if (ret)
57                 return ret;
58         if (write) {
59                 static int stfu;
60
61                 if (sysctl_drop_caches & 1) {
62                         iterate_supers(drop_pagecache_sb, NULL);
63                         count_vm_event(DROP_PAGECACHE);
64                 }
65                 if (sysctl_drop_caches & 2) {
66                         drop_slab();
67                         count_vm_event(DROP_SLAB);
68                 }
69                 if (!stfu) {
70                         pr_info("%s (%d): drop_caches: %d\n",
71                                 current->comm, task_pid_nr(current),
72                                 sysctl_drop_caches);
73                 }
74                 stfu |= sysctl_drop_caches & 4;
75         }
76         return 0;
77 }