1 // SPDX-License-Identifier: GPL-2.0 <<
2 /* 1 /*
3 * Implement the manual drop-all-pagecache fun 2 * Implement the manual drop-all-pagecache function
4 */ 3 */
5 4
6 #include <linux/pagemap.h> <<
7 #include <linux/kernel.h> 5 #include <linux/kernel.h>
8 #include <linux/mm.h> 6 #include <linux/mm.h>
9 #include <linux/fs.h> 7 #include <linux/fs.h>
10 #include <linux/writeback.h> 8 #include <linux/writeback.h>
11 #include <linux/sysctl.h> 9 #include <linux/sysctl.h>
12 #include <linux/gfp.h> 10 #include <linux/gfp.h>
13 #include <linux/swap.h> <<
14 #include "internal.h" 11 #include "internal.h"
15 12
16 /* A global variable is a bit ugly, but it kee 13 /* A global variable is a bit ugly, but it keeps the code simple */
17 int sysctl_drop_caches; 14 int sysctl_drop_caches;
18 15
19 static void drop_pagecache_sb(struct super_blo 16 static void drop_pagecache_sb(struct super_block *sb, void *unused)
20 { 17 {
21 struct inode *inode, *toput_inode = NU 18 struct inode *inode, *toput_inode = NULL;
22 19
23 spin_lock(&sb->s_inode_list_lock); 20 spin_lock(&sb->s_inode_list_lock);
24 list_for_each_entry(inode, &sb->s_inod 21 list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
25 spin_lock(&inode->i_lock); 22 spin_lock(&inode->i_lock);
26 /* <<
27 * We must skip inodes in unus <<
28 * inodes without pages but we <<
29 * we need to reschedule to av <<
30 */ <<
31 if ((inode->i_state & (I_FREEI 23 if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
32 (mapping_empty(inode->i_ma !! 24 (inode->i_mapping->nrpages == 0)) {
33 spin_unlock(&inode->i_ 25 spin_unlock(&inode->i_lock);
34 continue; 26 continue;
35 } 27 }
36 __iget(inode); 28 __iget(inode);
37 spin_unlock(&inode->i_lock); 29 spin_unlock(&inode->i_lock);
38 spin_unlock(&sb->s_inode_list_ 30 spin_unlock(&sb->s_inode_list_lock);
39 31
40 invalidate_mapping_pages(inode 32 invalidate_mapping_pages(inode->i_mapping, 0, -1);
41 iput(toput_inode); 33 iput(toput_inode);
42 toput_inode = inode; 34 toput_inode = inode;
43 35
44 cond_resched(); <<
45 spin_lock(&sb->s_inode_list_lo 36 spin_lock(&sb->s_inode_list_lock);
46 } 37 }
47 spin_unlock(&sb->s_inode_list_lock); 38 spin_unlock(&sb->s_inode_list_lock);
48 iput(toput_inode); 39 iput(toput_inode);
49 } 40 }
50 41
51 int drop_caches_sysctl_handler(const struct ct !! 42 int drop_caches_sysctl_handler(struct ctl_table *table, int write,
52 void *buffer, size_t *length, !! 43 void __user *buffer, size_t *length, loff_t *ppos)
53 { 44 {
54 int ret; 45 int ret;
55 46
56 ret = proc_dointvec_minmax(table, writ 47 ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
57 if (ret) 48 if (ret)
58 return ret; 49 return ret;
59 if (write) { 50 if (write) {
60 static int stfu; 51 static int stfu;
61 52
62 if (sysctl_drop_caches & 1) { 53 if (sysctl_drop_caches & 1) {
63 lru_add_drain_all(); <<
64 iterate_supers(drop_pa 54 iterate_supers(drop_pagecache_sb, NULL);
65 count_vm_event(DROP_PA 55 count_vm_event(DROP_PAGECACHE);
66 } 56 }
67 if (sysctl_drop_caches & 2) { 57 if (sysctl_drop_caches & 2) {
68 drop_slab(); 58 drop_slab();
69 count_vm_event(DROP_SL 59 count_vm_event(DROP_SLAB);
70 } 60 }
71 if (!stfu) { 61 if (!stfu) {
72 pr_info("%s (%d): drop 62 pr_info("%s (%d): drop_caches: %d\n",
73 current->comm, 63 current->comm, task_pid_nr(current),
74 sysctl_drop_ca 64 sysctl_drop_caches);
75 } 65 }
76 stfu |= sysctl_drop_caches & 4 66 stfu |= sysctl_drop_caches & 4;
77 } 67 }
78 return 0; 68 return 0;
79 } 69 }
80 70
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