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
  12 /* A global variable is a bit ugly, but it keeps the code simple */
  13 int sysctl_drop_caches;
  14
  15 static 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
  28 void drop_pagecache(void)
  29 {
  30         struct super_block *sb;
  31
  32         spin_lock(&sb_lock);
  33 restart:
  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
  48 void 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
  57 int 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 }