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1 | // SPDX-License-Identifier: GPL-2.0 | |
2 | /* | |
3 | * Implement the manual drop-all-pagecache function | |
4 | */ | |
5 | ||
6 | #include <linux/kernel.h> | |
7 | #include <linux/mm.h> | |
8 | #include <linux/fs.h> | |
9 | #include <linux/writeback.h> | |
10 | #include <linux/sysctl.h> | |
11 | #include <linux/gfp.h> | |
12 | #include "internal.h" | |
13 | ||
14 | /* A global variable is a bit ugly, but it keeps the code simple */ | |
15 | int sysctl_drop_caches; | |
16 | ||
17 | static void drop_pagecache_sb(struct super_block *sb, void *unused) | |
18 | { | |
19 | struct inode *inode, *toput_inode = NULL; | |
20 | ||
21 | spin_lock(&sb->s_inode_list_lock); | |
22 | list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { | |
23 | spin_lock(&inode->i_lock); | |
24 | if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) || | |
25 | (inode->i_mapping->nrpages == 0)) { | |
26 | spin_unlock(&inode->i_lock); | |
27 | continue; | |
28 | } | |
29 | __iget(inode); | |
30 | spin_unlock(&inode->i_lock); | |
31 | spin_unlock(&sb->s_inode_list_lock); | |
32 | ||
33 | invalidate_mapping_pages(inode->i_mapping, 0, -1); | |
34 | iput(toput_inode); | |
35 | toput_inode = inode; | |
36 | ||
37 | spin_lock(&sb->s_inode_list_lock); | |
38 | } | |
39 | spin_unlock(&sb->s_inode_list_lock); | |
40 | iput(toput_inode); | |
41 | } | |
42 | ||
43 | int drop_caches_sysctl_handler(struct ctl_table *table, int write, | |
44 | void __user *buffer, size_t *length, loff_t *ppos) | |
45 | { | |
46 | int ret; | |
47 | ||
48 | ret = proc_dointvec_minmax(table, write, buffer, length, ppos); | |
49 | if (ret) | |
50 | return ret; | |
51 | if (write) { | |
52 | static int stfu; | |
53 | ||
54 | if (sysctl_drop_caches & 1) { | |
55 | iterate_supers(drop_pagecache_sb, NULL); | |
56 | count_vm_event(DROP_PAGECACHE); | |
57 | } | |
58 | if (sysctl_drop_caches & 2) { | |
59 | drop_slab(); | |
60 | count_vm_event(DROP_SLAB); | |
61 | } | |
62 | if (!stfu) { | |
63 | pr_info("%s (%d): drop_caches: %d\n", | |
64 | current->comm, task_pid_nr(current), | |
65 | sysctl_drop_caches); | |
66 | } | |
67 | stfu |= sysctl_drop_caches & 4; | |
68 | } | |
69 | return 0; | |
70 | } |