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 <linux/export.h>
  12 #include "internal.h"
  13
  14 /* A global variable is a bit ugly, but it keeps the code simple */
  15 int sysctl_drop_caches;
  16
  17 static void drop_pagecache_sb(struct super_block *sb, void *unused)
  18 {
  19         struct inode *inode, *toput_inode = NULL;
  20
  21         spin_lock(&inode_sb_list_lock);
  22         list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
  23                 spin_lock(&inode->i_lock);
  24                 if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
  25                     (inode->i_mapping->nrpages == 0)) {
  26                         spin_unlock(&inode->i_lock);
  27                         continue;
  28                 }
  29                 __iget(inode);
  30                 spin_unlock(&inode->i_lock);
  31                 spin_unlock(&inode_sb_list_lock);
  32                 invalidate_mapping_pages(inode->i_mapping, 0, -1);
  33                 iput(toput_inode);
  34                 toput_inode = inode;
  35                 spin_lock(&inode_sb_list_lock);
  36         }
  37         spin_unlock(&inode_sb_list_lock);
  38         iput(toput_inode);
  39 }
  40
  41 static void drop_slab(void)
  42 {
  43         int nr_objects;
  44         struct shrink_control shrink = {
  45                 .gfp_mask = GFP_KERNEL,
  46         };
  47
  48         do {
  49                 nr_objects = shrink_slab(&shrink, 1000, 1000);
  50         } while (nr_objects > 10);
  51 }
  52
  53 /* For TuxOnIce */
  54 void drop_pagecache(void)
  55 {
  56         iterate_supers(drop_pagecache_sb, NULL);
  57 }
  58 EXPORT_SYMBOL_GPL(drop_pagecache);
  59
  60 int drop_caches_sysctl_handler(ctl_table *table, int write,
  61         void __user *buffer, size_t *length, loff_t *ppos)
  62 {
  63         int ret;
  64
  65         ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
  66         if (ret)
  67                 return ret;
  68         if (write) {
  69                 if (sysctl_drop_caches & 1)
  70                         iterate_supers(drop_pagecache_sb, NULL);
  71                 if (sysctl_drop_caches & 2)
  72                         drop_slab();
  73         }
  74         return 0;
  75 }