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Linux/fs/drop_caches.c

  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 

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