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 /* 23 /*
27 * We must skip inodes in unus 24 * We must skip inodes in unusual state. We may also skip
28 * inodes without pages but we 25 * inodes without pages but we deliberately won't in case
29 * we need to reschedule to av 26 * we need to reschedule to avoid softlockups.
30 */ 27 */
31 if ((inode->i_state & (I_FREEI 28 if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
32 (mapping_empty(inode->i_ma !! 29 (inode->i_mapping->nrpages == 0 && !need_resched())) {
33 spin_unlock(&inode->i_ 30 spin_unlock(&inode->i_lock);
34 continue; 31 continue;
35 } 32 }
36 __iget(inode); 33 __iget(inode);
37 spin_unlock(&inode->i_lock); 34 spin_unlock(&inode->i_lock);
38 spin_unlock(&sb->s_inode_list_ 35 spin_unlock(&sb->s_inode_list_lock);
39 36
>> 37 cond_resched();
40 invalidate_mapping_pages(inode 38 invalidate_mapping_pages(inode->i_mapping, 0, -1);
41 iput(toput_inode); 39 iput(toput_inode);
42 toput_inode = inode; 40 toput_inode = inode;
43 41
44 cond_resched(); <<
45 spin_lock(&sb->s_inode_list_lo 42 spin_lock(&sb->s_inode_list_lock);
46 } 43 }
47 spin_unlock(&sb->s_inode_list_lock); 44 spin_unlock(&sb->s_inode_list_lock);
48 iput(toput_inode); 45 iput(toput_inode);
49 } 46 }
50 47
51 int drop_caches_sysctl_handler(const struct ct !! 48 int drop_caches_sysctl_handler(struct ctl_table *table, int write,
52 void *buffer, size_t *length, !! 49 void __user *buffer, size_t *length, loff_t *ppos)
53 { 50 {
54 int ret; 51 int ret;
55 52
56 ret = proc_dointvec_minmax(table, writ 53 ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
57 if (ret) 54 if (ret)
58 return ret; 55 return ret;
59 if (write) { 56 if (write) {
60 static int stfu; 57 static int stfu;
61 58
62 if (sysctl_drop_caches & 1) { 59 if (sysctl_drop_caches & 1) {
63 lru_add_drain_all(); <<
64 iterate_supers(drop_pa 60 iterate_supers(drop_pagecache_sb, NULL);
65 count_vm_event(DROP_PA 61 count_vm_event(DROP_PAGECACHE);
66 } 62 }
67 if (sysctl_drop_caches & 2) { 63 if (sysctl_drop_caches & 2) {
68 drop_slab(); 64 drop_slab();
69 count_vm_event(DROP_SL 65 count_vm_event(DROP_SLAB);
70 } 66 }
71 if (!stfu) { 67 if (!stfu) {
72 pr_info("%s (%d): drop 68 pr_info("%s (%d): drop_caches: %d\n",
73 current->comm, 69 current->comm, task_pid_nr(current),
74 sysctl_drop_ca 70 sysctl_drop_caches);
75 } 71 }
76 stfu |= sysctl_drop_caches & 4 72 stfu |= sysctl_drop_caches & 4;
77 } 73 }
78 return 0; 74 return 0;
79 } 75 }
80 76
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