GFS2: Extend umount wait coverage to full glock lifetime
[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
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                 sb->s_count++;
44                 spin_unlock(&sb_lock);
45                 down_read(&sb->s_umount);
46                 if (sb->s_root)
47                         drop_pagecache_sb(sb);
48                 up_read(&sb->s_umount);
49                 spin_lock(&sb_lock);
50                 if (__put_super_and_need_restart(sb))
51                         goto restart;
52         }
53         spin_unlock(&sb_lock);
54 }
55
56 static void drop_slab(void)
57 {
58         int nr_objects;
59
60         do {
61                 nr_objects = shrink_slab(1000, GFP_KERNEL, 1000);
62         } while (nr_objects > 10);
63 }
64
65 int drop_caches_sysctl_handler(ctl_table *table, int write,
66         void __user *buffer, size_t *length, loff_t *ppos)
67 {
68         proc_dointvec_minmax(table, write, buffer, length, ppos);
69         if (write) {
70                 if (sysctl_drop_caches & 1)
71                         drop_pagecache();
72                 if (sysctl_drop_caches & 2)
73                         drop_slab();
74         }
75         return 0;
76 }