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
  12/* A global variable is a bit ugly, but it keeps the code simple */
  13int sysctl_drop_caches;
  14
  15static void drop_pagecache_sb(struct super_block *sb)
  16{
  17        struct inode *inode;
  18
  19        spin_lock(&inode_lock);
  20        list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
  21                if (inode->i_state & (I_FREEING|I_WILL_FREE))
  22                        continue;
  23                __invalidate_mapping_pages(inode->i_mapping, 0, -1, true);
  24        }
  25        spin_unlock(&inode_lock);
  26}
  27
  28void drop_pagecache(void)
  29{
  30        struct super_block *sb;
  31
  32        spin_lock(&sb_lock);
  33restart:
  34        list_for_each_entry(sb, &super_blocks, s_list) {
  35                sb->s_count++;
  36                spin_unlock(&sb_lock);
  37                down_read(&sb->s_umount);
  38                if (sb->s_root)
  39                        drop_pagecache_sb(sb);
  40                up_read(&sb->s_umount);
  41                spin_lock(&sb_lock);
  42                if (__put_super_and_need_restart(sb))
  43                        goto restart;
  44        }
  45        spin_unlock(&sb_lock);
  46}
  47
  48void drop_slab(void)
  49{
  50        int nr_objects;
  51
  52        do {
  53                nr_objects = shrink_slab(1000, GFP_KERNEL, 1000);
  54        } while (nr_objects > 10);
  55}
  56
  57int drop_caches_sysctl_handler(ctl_table *table, int write,
  58        struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
  59{
  60        proc_dointvec_minmax(table, write, file, buffer, length, ppos);
  61        if (write) {
  62                if (sysctl_drop_caches & 1)
  63                        drop_pagecache();
  64                if (sysctl_drop_caches & 2)
  65                        drop_slab();
  66        }
  67        return 0;
  68}
  69