fs: protect inode->i_state with inode->i_lock
[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, void *unused)
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                 spin_lock(&inode->i_lock);
22                 if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
23                     (inode->i_mapping->nrpages == 0)) {
24                         spin_unlock(&inode->i_lock);
25                         continue;
26                 }
27                 __iget(inode);
28                 spin_unlock(&inode->i_lock);
29                 spin_unlock(&inode_lock);
30                 invalidate_mapping_pages(inode->i_mapping, 0, -1);
31                 iput(toput_inode);
32                 toput_inode = inode;
33                 spin_lock(&inode_lock);
34         }
35         spin_unlock(&inode_lock);
36         iput(toput_inode);
37 }
38
39 static void drop_slab(void)
40 {
41         int nr_objects;
42
43         do {
44                 nr_objects = shrink_slab(1000, GFP_KERNEL, 1000);
45         } while (nr_objects > 10);
46 }
47
48 int drop_caches_sysctl_handler(ctl_table *table, int write,
49         void __user *buffer, size_t *length, loff_t *ppos)
50 {
51         int ret;
52
53         ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
54         if (ret)
55                 return ret;
56         if (write) {
57                 if (sysctl_drop_caches & 1)
58                         iterate_supers(drop_pagecache_sb, NULL);
59                 if (sysctl_drop_caches & 2)
60                         drop_slab();
61         }
62         return 0;
63 }