1/* 2 * Implement the manual drop-all-pagecache function 3 */ 4 5#include <linux/kernel.h> 6#include <linux/mm.h> 7#include <linux/fs.h> 8#include <linux/writeback.h> 9#include <linux/sysctl.h> 10#include <linux/gfp.h> 11 12/* A global variable is a bit ugly, but it keeps the code simple */ 13int sysctl_drop_caches; 14 15static void drop_pagecache_sb(struct super_block *sb, void *unused) 16{ 17 struct inode *inode, *toput_inode = NULL; 18 19 spin_lock(&inode_lock); 20 list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { 21 if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) 22 continue; 23 if (inode->i_mapping->nrpages == 0) 24 continue; 25 __iget(inode); 26 spin_unlock(&inode_lock); 27 invalidate_mapping_pages(inode->i_mapping, 0, -1); 28 iput(toput_inode); 29 toput_inode = inode; 30 spin_lock(&inode_lock); 31 } 32 spin_unlock(&inode_lock); 33 iput(toput_inode); 34} 35 36static void drop_slab(void) 37{ 38 int nr_objects; 39 40 do { 41 nr_objects = shrink_slab(1000, GFP_KERNEL, 1000); 42 } while (nr_objects > 10); 43} 44 45int drop_caches_sysctl_handler(ctl_table *table, int write, 46 void __user *buffer, size_t *length, loff_t *ppos) 47{ 48 proc_dointvec_minmax(table, write, buffer, length, ppos); 49 if (write) { 50 if (sysctl_drop_caches & 1) 51 iterate_supers(drop_pagecache_sb, NULL); 52 if (sysctl_drop_caches & 2) 53 drop_slab(); 54 } 55 return 0; 56} 57