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 #include "internal.h" 12 13 /* A global variable is a bit ugly, but it keeps the code simple */ 14 int sysctl_drop_caches; 15 16 static void drop_pagecache_sb(struct super_block *sb, void *unused) 17 { 18 struct inode *inode, *toput_inode = NULL; 19 20 spin_lock(&sb->s_inode_list_lock); 21 list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { 22 spin_lock(&inode->i_lock); 23 if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) || 24 (inode->i_mapping->nrpages == 0)) { 25 spin_unlock(&inode->i_lock); 26 continue; 27 } 28 __iget(inode); 29 spin_unlock(&inode->i_lock); 30 spin_unlock(&sb->s_inode_list_lock); 31 32 invalidate_mapping_pages(inode->i_mapping, 0, -1); 33 iput(toput_inode); 34 toput_inode = inode; 35 36 spin_lock(&sb->s_inode_list_lock); 37 } 38 spin_unlock(&sb->s_inode_list_lock); 39 iput(toput_inode); 40 } 41 42 int drop_caches_sysctl_handler(struct ctl_table *table, int write, 43 void __user *buffer, size_t *length, loff_t *ppos) 44 { 45 int ret; 46 47 ret = proc_dointvec_minmax(table, write, buffer, length, ppos); 48 if (ret) 49 return ret; 50 if (write) { 51 static int stfu; 52 53 if (sysctl_drop_caches & 1) { 54 iterate_supers(drop_pagecache_sb, NULL); 55 count_vm_event(DROP_PAGECACHE); 56 } 57 if (sysctl_drop_caches & 2) { 58 drop_slab(); 59 count_vm_event(DROP_SLAB); 60 } 61 if (!stfu) { 62 pr_info("%s (%d): drop_caches: %d\n", 63 current->comm, task_pid_nr(current), 64 sysctl_drop_caches); 65 } 66 stfu |= sysctl_drop_caches & 4; 67 } 68 return 0; 69 } 70