// SPDX-License-Identifier: GPL-2.0 /* * Implement the manual drop-all-pagecache function */ #include <linux/pagemap.h> #include <linux/kernel.h> #include <linux/mm.h> #include <linux/fs.h> #include <linux/writeback.h> #include <linux/sysctl.h> #include <linux/gfp.h> #include "internal.h" /* A global variable is a bit ugly, but it keeps the code simple */ int sysctl_drop_caches; static void drop_pagecache_sb(struct super_block *sb, void *unused) { struct inode *inode, *toput_inode = NULL; spin_lock(&sb->s_inode_list_lock); list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { spin_lock(&inode->i_lock); /* * We must skip inodes in unusual state. We may also skip * inodes without pages but we deliberately won't in case * we need to reschedule to avoid softlockups. */ if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) || (mapping_empty(inode->i_mapping) && !need_resched())) { spin_unlock(&inode->i_lock); continue; } __iget(inode); spin_unlock(&inode->i_lock); spin_unlock(&sb->s_inode_list_lock); invalidate_mapping_pages(inode->i_mapping, 0, -1); iput(toput_inode); toput_inode = inode; cond_resched(); spin_lock(&sb->s_inode_list_lock); } spin_unlock(&sb->s_inode_list_lock); iput(toput_inode); } int drop_caches_sysctl_handler(struct ctl_table *table, int write, void *buffer, size_t *length, loff_t *ppos) { int ret; ret = proc_dointvec_minmax(table, write, buffer, length, ppos); if (ret) return ret; if (write) { static int stfu; if (sysctl_drop_caches & 1) { iterate_supers(drop_pagecache_sb, NULL); count_vm_event(DROP_PAGECACHE); } if (sysctl_drop_caches & 2) { drop_slab(); count_vm_event(DROP_SLAB); } if (!stfu) { pr_info("%s (%d): drop_caches: %d\n", current->comm, task_pid_nr(current), sysctl_drop_caches); } stfu |= sysctl_drop_caches & 4; } return 0; }