LXR linux/fs/drop

   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
  44        do {
  45                nr_objects = shrink_slab(1000, GFP_KERNEL, 1000);
  46        } while (nr_objects > 10);
  47}
  48
  49int drop_caches_sysctl_handler(ctl_table *table, int write,
  50        void __user *buffer, size_t *length, loff_t *ppos)
  51{
  52        int ret;
  53
  54        ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
  55        if (ret)
  56                return ret;
  57        if (write) {
  58                if (sysctl_drop_caches & 1)
  59                        iterate_supers(drop_pagecache_sb, NULL);
  60                if (sysctl_drop_caches & 2)
  61                        drop_slab();
  62        }
  63        return 0;
  64}
  65