LXR linux/fs/drop

   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 */
  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                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
  43int 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}
  71