text: /*
   * Copyright (C) 2005-2014 Junjiro R. Okajima
   *
   * This program, aufs is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
   */
  
  /*
   * magic sysrq hanlder
   */
  
  /* #include <linux/sysrq.h> */
  #include <linux/writeback.h>
  #include "aufs.h"
  
  /* ---------------------------------------------------------------------- */
  
  static void sysrq_sb(struct super_block *sb)
  {
  	char *plevel;
  	struct au_sbinfo *sbinfo;
  	struct file *file;
  
  	plevel = au_plevel;
  	au_plevel = KERN_WARNING;
  
  	/* since we define pr_fmt, call printk directly */
  #define pr(str) printk(KERN_WARNING AUFS_NAME ": " str)
  
  	sbinfo = au_sbi(sb);
  	printk(KERN_WARNING "si=%lx\n", sysaufs_si_id(sbinfo));
  	pr("superblock\n");
  	au_dpri_sb(sb);
  
  #if 0
  	pr("root dentry\n");
  	au_dpri_dentry(sb->s_root);
  	pr("root inode\n");
  	au_dpri_inode(sb->s_root->d_inode);
  #endif
  
  #if 0
  	do {
  		int err, i, j, ndentry;
  		struct au_dcsub_pages dpages;
  		struct au_dpage *dpage;
  
  		err = au_dpages_init(&dpages, GFP_ATOMIC);
  		if (unlikely(err))
  			break;
  		err = au_dcsub_pages(&dpages, sb->s_root, NULL, NULL);
  		if (!err)
  			for (i = 0; i < dpages.ndpage; i++) {
  				dpage = dpages.dpages + i;
  				ndentry = dpage->ndentry;
  				for (j = 0; j < ndentry; j++)
  					au_dpri_dentry(dpage->dentries[j]);
  			}
  		au_dpages_free(&dpages);
  	} while (0);
  #endif
  
  #if 1
  	{
  		struct inode *i;
  
  		pr("isolated inode\n");
  		spin_lock(&inode_sb_list_lock);
  		list_for_each_entry(i, &sb->s_inodes, i_sb_list) {
  			spin_lock(&i->i_lock);
  			if (1 || hlist_empty(&i->i_dentry))
  				au_dpri_inode(i);
  			spin_unlock(&i->i_lock);
  		}
  		spin_unlock(&inode_sb_list_lock);
  	}
  #endif
  	pr("files\n");
  	lg_global_lock(&files_lglock);
  	do_file_list_for_each_entry(sb, file) {
  		umode_t mode;
  
  		mode = file_inode(file)->i_mode;
  		if (!special_file(mode))
  			au_dpri_file(file);
  	} while_file_list_for_each_entry;
  	lg_global_unlock(&files_lglock);
  	pr("done\n");
  
  #undef pr
  	au_plevel = plevel;
  }
  
  /* ---------------------------------------------------------------------- */
  
  /* module parameter */
  static char *aufs_sysrq_key = "a";
  module_param_named(sysrq, aufs_sysrq_key, charp, S_IRUGO);
  MODULE_PARM_DESC(sysrq, "MagicSysRq key for " AUFS_NAME);
  
  static void au_sysrq(int key __maybe_unused)
  {
  	struct au_sbinfo *sbinfo;
  
  	lockdep_off();
  	au_sbilist_lock();
  	list_for_each_entry(sbinfo, &au_sbilist.head, si_list)
  		sysrq_sb(sbinfo->si_sb);
  	au_sbilist_unlock();
  	lockdep_on();
  }
  
  static struct sysrq_key_op au_sysrq_op = {
  	.handler	= au_sysrq,
  	.help_msg	= "Aufs",
  	.action_msg	= "Aufs",
  	.enable_mask	= SYSRQ_ENABLE_DUMP
  };
  
  /* ---------------------------------------------------------------------- */
  
  int __init au_sysrq_init(void)
  {
  	int err;
  	char key;
  
  	err = -1;
  	key = *aufs_sysrq_key;
  	if ('a' <= key && key <= 'z')
  		err = register_sysrq_key(key, &au_sysrq_op);
  	if (unlikely(err))
  		pr_err("err %d, sysrq=%c\n", err, key);
  	return err;
  }
  
  void au_sysrq_fin(void)
  {
  	int err;
  
  	err = unregister_sysrq_key(*aufs_sysrq_key, &au_sysrq_op);
  	if (unlikely(err))
  		pr_err("err %d (ignored)\n", err);
  }
  