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, *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))
  22                         continue;
  23                 __iget(inode);
  24                 spin_unlock(&inode_lock);
  25                 __invalidate_mapping_pages(inode->i_mapping, 0, -1, true);
  26                 iput(toput_inode);
  27                 toput_inode = inode;
  28                 spin_lock(&inode_lock);
  29         }
  30         spin_unlock(&inode_lock);
  31         iput(toput_inode);
  32 }
  33
  34 static void drop_pagecache(void)
  35 {
  36         struct super_block *sb;
  37
  38         spin_lock(&sb_lock);
  39 restart:
  40         list_for_each_entry(sb, &super_blocks, s_list) {
  41                 sb->s_count++;
  42                 spin_unlock(&sb_lock);
  43                 down_read(&sb->s_umount);
  44                 if (sb->s_root)
  45                         drop_pagecache_sb(sb);
  46                 up_read(&sb->s_umount);
  47                 spin_lock(&sb_lock);
  48                 if (__put_super_and_need_restart(sb))
  49                         goto restart;
  50         }
  51         spin_unlock(&sb_lock);
  52 }
  53
  54 static void drop_slab(void)
  55 {
  56         int nr_objects;
  57
  58         do {
  59                 nr_objects = shrink_slab(1000, GFP_KERNEL, 1000);
  60         } while (nr_objects > 10);
  61 }
  62
  63 int drop_caches_sysctl_handler(ctl_table *table, int write,
  64         struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
  65 {
  66         proc_dointvec_minmax(table, write, file, buffer, length, ppos);
  67         if (write) {
  68                 if (sysctl_drop_caches & 1)
  69                         drop_pagecache();
  70                 if (sysctl_drop_caches & 2)
  71                         drop_slab();
  72         }
  73         return 0;
  74 }