fs/drop_caches.c

   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 */
  14 int sysctl_drop_caches;
  15
  16 static void drop_pagecache_sb(struct super_block *sb, void *unused)
  17 {
  18         struct inode *inode, *toput_inode = NULL;
  19
  20         spin_lock(&sb->s_inode_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(&sb->s_inode_list_lock);
  31
  32                 invalidate_mapping_pages(inode->i_mapping, 0, -1);
  33                 iput(toput_inode);
  34                 toput_inode = inode;
  35
  36                 spin_lock(&sb->s_inode_list_lock);
  37         }
  38         spin_unlock(&sb->s_inode_list_lock);
  39         iput(toput_inode);
  40 }
  41
  42 int drop_caches_sysctl_handler(struct ctl_table *table, int write,
  43         void __user *buffer, size_t *length, loff_t *ppos)
  44 {
  45         int ret;
  46
  47         ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
  48         if (ret)
  49                 return ret;
  50         if (write) {
  51                 static int stfu;
  52
  53                 if (sysctl_drop_caches & 1) {
  54                         iterate_supers(drop_pagecache_sb, NULL);
  55                         count_vm_event(DROP_PAGECACHE);
  56                 }
  57                 if (sysctl_drop_caches & 2) {
  58                         drop_slab();
  59                         count_vm_event(DROP_SLAB);
  60                 }
  61                 if (!stfu) {
  62                         pr_info("%s (%d): drop_caches: %d\n",
  63                                 current->comm, task_pid_nr(current),
  64                                 sysctl_drop_caches);
  65                 }
  66                 stfu |= sysctl_drop_caches & 4;
  67         }
  68         return 0;
  69 }