#include <linux/reiserfs_fs.h>
  #include <linux/mutex.h>
  
  /*
   * The previous reiserfs locking scheme was heavily based on
   * the tricky properties of the Bkl:
   *
   * - it was acquired recursively by a same task
   * - the performances relied on the release-while-schedule() property
   *
   * Now that we replace it by a mutex, we still want to keep the same
   * recursive property to avoid big changes in the code structure.
   * We use our own lock_owner here because the owner field on a mutex
   * is only available in SMP or mutex debugging, also we only need this field
   * for this mutex, no need for a system wide mutex facility.
   *
   * Also this lock is often released before a call that could block because

   * reiserfs performances were partially based on the release while schedule()

   * property of the Bkl.
   */
  void reiserfs_write_lock(struct super_block *s)
  {
  	struct reiserfs_sb_info *sb_i = REISERFS_SB(s);
  
  	if (sb_i->lock_owner != current) {
  		mutex_lock(&sb_i->lock);
  		sb_i->lock_owner = current;
  	}
  
  	/* No need to protect it, only the current task touches it */
  	sb_i->lock_depth++;
  }
  
  void reiserfs_write_unlock(struct super_block *s)
  {
  	struct reiserfs_sb_info *sb_i = REISERFS_SB(s);
  
  	/*
  	 * Are we unlocking without even holding the lock?

  	 * Such a situation must raise a BUG() if we don't want
  	 * to corrupt the data.

  	 */

  	BUG_ON(sb_i->lock_owner != current);

  
  	if (--sb_i->lock_depth == -1) {
  		sb_i->lock_owner = NULL;
  		mutex_unlock(&sb_i->lock);
  	}
  }
  
  /*

   * If we already own the lock, just exit and don't increase the depth.
   * Useful when we don't want to lock more than once.
   *
   * We always return the lock_depth we had before calling
   * this function.
   */
  int reiserfs_write_lock_once(struct super_block *s)
  {
  	struct reiserfs_sb_info *sb_i = REISERFS_SB(s);
  
  	if (sb_i->lock_owner != current) {
  		mutex_lock(&sb_i->lock);
  		sb_i->lock_owner = current;
  		return sb_i->lock_depth++;
  	}
  
  	return sb_i->lock_depth;
  }
  
  void reiserfs_write_unlock_once(struct super_block *s, int lock_depth)
  {
  	if (lock_depth == -1)
  		reiserfs_write_unlock(s);
  }
  
  /*

   * Utility function to force a BUG if it is called without the superblock
   * write lock held.  caller is the string printed just before calling BUG()
   */
  void reiserfs_check_lock_depth(struct super_block *sb, char *caller)
  {
  	struct reiserfs_sb_info *sb_i = REISERFS_SB(sb);
  
  	if (sb_i->lock_depth < 0)
  		reiserfs_panic(sb, "%s called without kernel lock held %d",
  			       caller);
  }

  
  #ifdef CONFIG_REISERFS_CHECK
  void reiserfs_lock_check_recursive(struct super_block *sb)
  {
  	struct reiserfs_sb_info *sb_i = REISERFS_SB(sb);
  
  	WARN_ONCE((sb_i->lock_depth > 0), "Unwanted recursive reiserfs lock!
  ");
  }
  #endif