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1// SPDX-License-Identifier: GPL-2.02/*3 * Implement the manual drop-all-pagecache function4 */5 6#include <linux/pagemap.h>7#include <linux/kernel.h>8#include <linux/mm.h>9#include <linux/fs.h>10#include <linux/writeback.h>11#include <linux/sysctl.h>12#include <linux/gfp.h>13#include <linux/swap.h>14#include "internal.h"15 16/* A global variable is a bit ugly, but it keeps the code simple */17int sysctl_drop_caches;18 19static HWJS_SUSPENDS void drop_pagecache_sb(struct super_block *sb, void *unused)20{21 struct inode *inode, *toput_inode = NULL;22 23 spin_lock(&sb->s_inode_list_lock);24 list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {25 spin_lock(&inode->i_lock);26 /*27 * We must skip inodes in unusual state. We may also skip28 * inodes without pages but we deliberately won't in case29 * we need to reschedule to avoid softlockups.30 */31 if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||32 (mapping_empty(inode->i_mapping) && !need_resched())) {33 spin_unlock(&inode->i_lock);34 continue;35 }36 __iget(inode);37 spin_unlock(&inode->i_lock);38 spin_unlock(&sb->s_inode_list_lock);39 40 invalidate_mapping_pages(inode->i_mapping, 0, -1);41 iput(toput_inode);42 toput_inode = inode;43 44 cond_resched();45 spin_lock(&sb->s_inode_list_lock);46 }47 spin_unlock(&sb->s_inode_list_lock);48 iput(toput_inode);49}50 51int drop_caches_sysctl_handler(const struct ctl_table *table, int write,52 void *buffer, size_t *length, loff_t *ppos)53{54 int ret;55 56 ret = proc_dointvec_minmax(table, write, buffer, length, ppos);57 if (ret)58 return ret;59 if (write) {60 static int stfu;61 62 if (sysctl_drop_caches & 1) {63 lru_add_drain_all();64 iterate_supers(drop_pagecache_sb, NULL);65 count_vm_event(DROP_PAGECACHE);66 }67 if (sysctl_drop_caches & 2) {68 drop_slab();69 count_vm_event(DROP_SLAB);70 }71 if (!stfu) {72 pr_info("%s (%d): drop_caches: %d\n",73 current->comm, task_pid_nr(current),74 sysctl_drop_caches);75 }76 stfu |= sysctl_drop_caches & 4;77 }78 return 0;79}80