SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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)
  17 {
  18         struct inode *inode, *toput_inode = NULL;
  19
  20         spin_lock(&inode_lock);
  21         list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
  22                 if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW))
  23                         continue;
  24                 if (inode->i_mapping->nrpages == 0)
  25                         continue;
  26                 __iget(inode);
  27                 spin_unlock(&inode_lock);
  28                 invalidate_mapping_pages(inode->i_mapping, 0, -1);
  29                 iput(toput_inode);
  30                 toput_inode = inode;
  31                 spin_lock(&inode_lock);
  32         }
  33         spin_unlock(&inode_lock);
  34         iput(toput_inode);
  35 }
  36
  37 static void drop_pagecache(void)
  38 {
  39         struct super_block *sb, *n;
  40
  41         spin_lock(&sb_lock);
  42         list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
  43                 if (list_empty(&sb->s_instances))
  44                         continue;
  45                 sb->s_count++;
  46                 spin_unlock(&sb_lock);
  47                 down_read(&sb->s_umount);
  48                 if (sb->s_root)
  49                         drop_pagecache_sb(sb);
  50                 up_read(&sb->s_umount);
  51                 spin_lock(&sb_lock);
  52                 __put_super(sb);
  53         }
  54         spin_unlock(&sb_lock);
  55 }
  56
  57 static void drop_slab(void)
  58 {
  59         int nr_objects;
  60
  61         do {
  62                 nr_objects = shrink_slab(1000, GFP_KERNEL, 1000);
  63         } while (nr_objects > 10);
  64 }
  65
  66 int drop_caches_sysctl_handler(ctl_table *table, int write,
  67         void __user *buffer, size_t *length, loff_t *ppos)
  68 {
  69         proc_dointvec_minmax(table, write, buffer, length, ppos);
  70         if (write) {
  71                 if (sysctl_drop_caches & 1)
  72                         drop_pagecache();
  73                 if (sysctl_drop_caches & 2)
  74                         drop_slab();
  75         }
  76         return 0;
  77 }