Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) // SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3)  * Implement the manual drop-all-pagecache function
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6) #include <linux/kernel.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7) #include <linux/mm.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8) #include <linux/fs.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9) #include <linux/writeback.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) #include <linux/sysctl.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) #include <linux/gfp.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) #include "internal.h"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) /* A global variable is a bit ugly, but it keeps the code simple */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) int sysctl_drop_caches;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) static void drop_pagecache_sb(struct super_block *sb, void *unused)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) 	struct inode *inode, *toput_inode = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) 	spin_lock(&sb->s_inode_list_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) 	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) 		spin_lock(&inode->i_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) 		/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) 		 * We must skip inodes in unusual state. We may also skip
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) 		 * inodes without pages but we deliberately won't in case
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) 		 * we need to reschedule to avoid softlockups.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) 		 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) 		if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) 		    (inode->i_mapping->nrpages == 0 && !need_resched())) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) 			spin_unlock(&inode->i_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) 			continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) 		__iget(inode);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) 		spin_unlock(&inode->i_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) 		spin_unlock(&sb->s_inode_list_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) 		invalidate_mapping_pages(inode->i_mapping, 0, -1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) 		iput(toput_inode);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) 		toput_inode = inode;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) 		cond_resched();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) 		spin_lock(&sb->s_inode_list_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) 	spin_unlock(&sb->s_inode_list_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) 	iput(toput_inode);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) int drop_caches_sysctl_handler(struct ctl_table *table, int write,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) 		void *buffer, size_t *length, loff_t *ppos)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) 	int ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) 	ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) 	if (ret)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) 		return ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) 	if (write) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) 		static int stfu;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) 		if (sysctl_drop_caches & 1) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) 			iterate_supers(drop_pagecache_sb, NULL);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) 			count_vm_event(DROP_PAGECACHE);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) 		if (sysctl_drop_caches & 2) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) 			drop_slab();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) 			count_vm_event(DROP_SLAB);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) 		if (!stfu) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) 			pr_info("%s (%d): drop_caches: %d\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) 				current->comm, task_pid_nr(current),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) 				sysctl_drop_caches);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) 		stfu |= sysctl_drop_caches & 4;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) 	return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) }