81 lines
1.8 KiB
C
Executable File
81 lines
1.8 KiB
C
Executable File
/*
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* Implement the manual drop-all-pagecache function
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*/
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/fs.h>
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#include <linux/writeback.h>
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#include <linux/sysctl.h>
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#include <linux/gfp.h>
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#include "internal.h"
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/* A global variable is a bit ugly, but it keeps the code simple */
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int sysctl_drop_caches;
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static void drop_pagecache_sb(struct super_block *sb, void *unused)
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{
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struct inode *inode, *toput_inode = NULL;
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spin_lock(&inode_sb_list_lock);
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list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
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spin_lock(&inode->i_lock);
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if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
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(inode->i_mapping->nrpages == 0)) {
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spin_unlock(&inode->i_lock);
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continue;
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}
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__iget(inode);
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spin_unlock(&inode->i_lock);
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spin_unlock(&inode_sb_list_lock);
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invalidate_mapping_pages(inode->i_mapping, 0, -1);
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iput(toput_inode);
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toput_inode = inode;
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spin_lock(&inode_sb_list_lock);
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}
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spin_unlock(&inode_sb_list_lock);
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iput(toput_inode);
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}
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static void drop_slab(void)
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{
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int nr_objects;
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struct shrink_control shrink = {
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.gfp_mask = GFP_KERNEL,
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};
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nodes_setall(shrink.nodes_to_scan);
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do {
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nr_objects = shrink_slab(&shrink, 1000, 1000);
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} while (nr_objects > 10);
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}
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int drop_caches_sysctl_handler(struct ctl_table *table, int write,
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void __user *buffer, size_t *length, loff_t *ppos)
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{
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int ret;
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ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
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if (ret)
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return ret;
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if (write) {
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static int stfu;
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if (sysctl_drop_caches & 1) {
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iterate_supers(drop_pagecache_sb, NULL);
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count_vm_event(DROP_PAGECACHE);
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}
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if (sysctl_drop_caches & 2) {
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drop_slab();
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count_vm_event(DROP_SLAB);
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}
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if (!stfu) {
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pr_info("%s (%d): drop_caches: %d\n",
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current->comm, task_pid_nr(current),
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sysctl_drop_caches);
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}
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stfu |= sysctl_drop_caches & 4;
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}
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return 0;
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}
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