1 // SPDX-License-Identifier: GPL-2.0 1 // SPDX-License-Identifier: GPL-2.0
2 /* 2 /*
3 * Implement the manual drop-all-pagecache fun 3 * Implement the manual drop-all-pagecache function
4 */ 4 */
5 5
6 #include <linux/pagemap.h> 6 #include <linux/pagemap.h>
7 #include <linux/kernel.h> 7 #include <linux/kernel.h>
8 #include <linux/mm.h> 8 #include <linux/mm.h>
9 #include <linux/fs.h> 9 #include <linux/fs.h>
10 #include <linux/writeback.h> 10 #include <linux/writeback.h>
11 #include <linux/sysctl.h> 11 #include <linux/sysctl.h>
12 #include <linux/gfp.h> 12 #include <linux/gfp.h>
13 #include <linux/swap.h> <<
14 #include "internal.h" 13 #include "internal.h"
15 14
16 /* A global variable is a bit ugly, but it kee 15 /* A global variable is a bit ugly, but it keeps the code simple */
17 int sysctl_drop_caches; 16 int sysctl_drop_caches;
18 17
19 static void drop_pagecache_sb(struct super_blo 18 static void drop_pagecache_sb(struct super_block *sb, void *unused)
20 { 19 {
21 struct inode *inode, *toput_inode = NU 20 struct inode *inode, *toput_inode = NULL;
22 21
23 spin_lock(&sb->s_inode_list_lock); 22 spin_lock(&sb->s_inode_list_lock);
24 list_for_each_entry(inode, &sb->s_inod 23 list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
25 spin_lock(&inode->i_lock); 24 spin_lock(&inode->i_lock);
26 /* 25 /*
27 * We must skip inodes in unus 26 * We must skip inodes in unusual state. We may also skip
28 * inodes without pages but we 27 * inodes without pages but we deliberately won't in case
29 * we need to reschedule to av 28 * we need to reschedule to avoid softlockups.
30 */ 29 */
31 if ((inode->i_state & (I_FREEI 30 if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
32 (mapping_empty(inode->i_ma 31 (mapping_empty(inode->i_mapping) && !need_resched())) {
33 spin_unlock(&inode->i_ 32 spin_unlock(&inode->i_lock);
34 continue; 33 continue;
35 } 34 }
36 __iget(inode); 35 __iget(inode);
37 spin_unlock(&inode->i_lock); 36 spin_unlock(&inode->i_lock);
38 spin_unlock(&sb->s_inode_list_ 37 spin_unlock(&sb->s_inode_list_lock);
39 38
40 invalidate_mapping_pages(inode 39 invalidate_mapping_pages(inode->i_mapping, 0, -1);
41 iput(toput_inode); 40 iput(toput_inode);
42 toput_inode = inode; 41 toput_inode = inode;
43 42
44 cond_resched(); 43 cond_resched();
45 spin_lock(&sb->s_inode_list_lo 44 spin_lock(&sb->s_inode_list_lock);
46 } 45 }
47 spin_unlock(&sb->s_inode_list_lock); 46 spin_unlock(&sb->s_inode_list_lock);
48 iput(toput_inode); 47 iput(toput_inode);
49 } 48 }
50 49
51 int drop_caches_sysctl_handler(const struct ct !! 50 int drop_caches_sysctl_handler(struct ctl_table *table, int write,
52 void *buffer, size_t *length, 51 void *buffer, size_t *length, loff_t *ppos)
53 { 52 {
54 int ret; 53 int ret;
55 54
56 ret = proc_dointvec_minmax(table, writ 55 ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
57 if (ret) 56 if (ret)
58 return ret; 57 return ret;
59 if (write) { 58 if (write) {
60 static int stfu; 59 static int stfu;
61 60
62 if (sysctl_drop_caches & 1) { 61 if (sysctl_drop_caches & 1) {
63 lru_add_drain_all(); <<
64 iterate_supers(drop_pa 62 iterate_supers(drop_pagecache_sb, NULL);
65 count_vm_event(DROP_PA 63 count_vm_event(DROP_PAGECACHE);
66 } 64 }
67 if (sysctl_drop_caches & 2) { 65 if (sysctl_drop_caches & 2) {
68 drop_slab(); 66 drop_slab();
69 count_vm_event(DROP_SL 67 count_vm_event(DROP_SLAB);
70 } 68 }
71 if (!stfu) { 69 if (!stfu) {
72 pr_info("%s (%d): drop 70 pr_info("%s (%d): drop_caches: %d\n",
73 current->comm, 71 current->comm, task_pid_nr(current),
74 sysctl_drop_ca 72 sysctl_drop_caches);
75 } 73 }
76 stfu |= sysctl_drop_caches & 4 74 stfu |= sysctl_drop_caches & 4;
77 } 75 }
78 return 0; 76 return 0;
79 } 77 }
80 78
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