9cd4e4a70f56d80126c685bebe41dd7e85b0a3fc
[linux-3.10.git] / 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_CLEAR|I_WILL_FREE|I_NEW))
22                         continue;
23                 if (inode->i_mapping->nrpages == 0)
24                         continue;
25                 __iget(inode);
26                 spin_unlock(&inode_lock);
27                 invalidate_mapping_pages(inode->i_mapping, 0, -1);
28                 iput(toput_inode);
29                 toput_inode = inode;
30                 spin_lock(&inode_lock);
31         }
32         spin_unlock(&inode_lock);
33         iput(toput_inode);
34 }
35
36 static void drop_pagecache(void)
37 {
38         struct super_block *sb;
39
40         spin_lock(&sb_lock);
41 restart:
42         list_for_each_entry(sb, &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                 if (__put_super_and_need_restart(sb))
53                         goto restart;
54         }
55         spin_unlock(&sb_lock);
56 }
57
58 static void drop_slab(void)
59 {
60         int nr_objects;
61
62         do {
63                 nr_objects = shrink_slab(1000, GFP_KERNEL, 1000);
64         } while (nr_objects > 10);
65 }
66
67 int drop_caches_sysctl_handler(ctl_table *table, int write,
68         void __user *buffer, size_t *length, loff_t *ppos)
69 {
70         proc_dointvec_minmax(table, write, buffer, length, ppos);
71         if (write) {
72                 if (sysctl_drop_caches & 1)
73                         drop_pagecache();
74                 if (sysctl_drop_caches & 2)
75                         drop_slab();
76         }
77         return 0;
78 }