Bury __put_super_and_need_restart()
[linux-2.6.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 #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 }