linux/fs/drop_caches.c
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   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        nodes_setall(shrink.nodes_to_scan);
  48        do {
  49                nr_objects = shrink_slab(&shrink, 1000, 1000);
  50        } while (nr_objects > 10);
  51}
  52
  53int drop_caches_sysctl_handler(ctl_table *table, int write,
  54        void __user *buffer, size_t *length, loff_t *ppos)
  55{
  56        int ret;
  57
  58        ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
  59        if (ret)
  60                return ret;
  61        if (write) {
  62                if (sysctl_drop_caches & 1)
  63                        iterate_supers(drop_pagecache_sb, NULL);
  64                if (sysctl_drop_caches & 2)
  65                        drop_slab();
  66        }
  67        return 0;
  68}
  69
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