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kernel/linux-imx6_3.14.28/fs/xfs/mrlock.h 2.18 KB
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  /*
   * Copyright (c) 2000-2006 Silicon Graphics, Inc.
   * All Rights Reserved.
   *
   * This program 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.
   *
   * This program is distributed in the hope that it would 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, write the Free Software Foundation,
   * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   */
  #ifndef __XFS_SUPPORT_MRLOCK_H__
  #define __XFS_SUPPORT_MRLOCK_H__
  
  #include <linux/rwsem.h>
  
  typedef struct {
  	struct rw_semaphore	mr_lock;
  #if defined(DEBUG) || defined(XFS_WARN)
  	int			mr_writer;
  #endif
  } mrlock_t;
  
  #if defined(DEBUG) || defined(XFS_WARN)
  #define mrinit(mrp, name)	\
  	do { (mrp)->mr_writer = 0; init_rwsem(&(mrp)->mr_lock); } while (0)
  #else
  #define mrinit(mrp, name)	\
  	do { init_rwsem(&(mrp)->mr_lock); } while (0)
  #endif
  
  #define mrlock_init(mrp, t,n,s)	mrinit(mrp, n)
  #define mrfree(mrp)		do { } while (0)
  
  static inline void mraccess_nested(mrlock_t *mrp, int subclass)
  {
  	down_read_nested(&mrp->mr_lock, subclass);
  }
  
  static inline void mrupdate_nested(mrlock_t *mrp, int subclass)
  {
  	down_write_nested(&mrp->mr_lock, subclass);
  #if defined(DEBUG) || defined(XFS_WARN)
  	mrp->mr_writer = 1;
  #endif
  }
  
  static inline int mrtryaccess(mrlock_t *mrp)
  {
  	return down_read_trylock(&mrp->mr_lock);
  }
  
  static inline int mrtryupdate(mrlock_t *mrp)
  {
  	if (!down_write_trylock(&mrp->mr_lock))
  		return 0;
  #if defined(DEBUG) || defined(XFS_WARN)
  	mrp->mr_writer = 1;
  #endif
  	return 1;
  }
  
  static inline void mrunlock_excl(mrlock_t *mrp)
  {
  #if defined(DEBUG) || defined(XFS_WARN)
  	mrp->mr_writer = 0;
  #endif
  	up_write(&mrp->mr_lock);
  }
  
  static inline void mrunlock_shared(mrlock_t *mrp)
  {
  	up_read(&mrp->mr_lock);
  }
  
  static inline void mrdemote(mrlock_t *mrp)
  {
  #if defined(DEBUG) || defined(XFS_WARN)
  	mrp->mr_writer = 0;
  #endif
  	downgrade_write(&mrp->mr_lock);
  }
  
  #endif /* __XFS_SUPPORT_MRLOCK_H__ */