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, void *unused)
  16{
  17        struct inode *inode, *toput_inode = NULL;
  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|I_NEW))
  22                        continue;
  23                if (inode->i_mapping->nrpages == 0)
  24                        continue;
  25                __iget(inode);
  26                spin_unlock(&inode_lock);
  27                invalidate_mapping_pages(inode->i_mapping, 0, -1);
  28                iput(toput_inode);
  29                toput_inode = inode;
  30                spin_lock(&inode_lock);
  31        }
  32        spin_unlock(&inode_lock);
  33        iput(toput_inode);
  34}
  35
  36static void drop_slab(void)
  37{
  38        int nr_objects;
  39
  40        do {
  41                nr_objects = shrink_slab(1000, GFP_KERNEL, 1000);
  42        } while (nr_objects > 10);
  43}
  44
  45int drop_caches_sysctl_handler(ctl_table *table, int write,
  46        void __user *buffer, size_t *length, loff_t *ppos)
  47{
  48        proc_dointvec_minmax(table, write, buffer, length, ppos);
  49        if (write) {
  50                if (sysctl_drop_caches & 1)
  51                        iterate_supers(drop_pagecache_sb, NULL);
  52                if (sysctl_drop_caches & 2)
  53                        drop_slab();
  54        }
  55        return 0;
  56}
  57