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 struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
67 {
68 proc_dointvec_minmax(table, write, file, 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 }
77
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