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