[linux-lvm] Re: Reverting "bd_mount_mutex" to "bd_mount_sem"

[Sergej Smirnov]

Reply-To: foma3 at hotmail.com

Hi.
You need comment? I have some for you:
----------------------------------------------------------------------
#if 0
/* old: */
#define MOUNT_SEMUTEX_IS_MUTEX yes
#undef MOUNT_SEMUTEX_IS_SEMAPHORE
#else
/* new: */
#undef MOUNT_SEMUTEX_IS_MUTEX
#define MOUNT_SEMUTEX_IS_SEMAPHORE yes
#endif
----------------------------------------------------------------------
#ifdef MOUNT_SEMUTEX_IS_MUTEX
#ifdef MOUNT_SEMUTEX_IS_SEMAPHORE
#error "both defined"
#else
#define INIT_MOUNT_SEMUTEX(x) mutex_init(&x->bd_mount_mutex)
#define LOCK_MOUNT_SEMUTEX(x) mutex_lock(&x->bd_mount_mutex)
#define UNLOCK_MOUNT_SEMUTEX(x) mutex_unlock(&x->bd_mount_mutex)
#endif
#else
#ifdef MOUNT_SEMUTEX_IS_SEMAPHORE
#define INIT_MOUNT_SEMUTEX(x) sema_init(&x->bd_mount_sem, 1)
#define LOCK_MOUNT_SEMUTEX(x) down(&x->bd_mount_sem)
#define UNLOCK_MOUNT_SEMUTEX(x) up(&x->bd_mount_sem)
#else
#error "none defined"
#endif
#endif
----------------------------------------------------------------------
   	{
   		memset(bdev, 0, sizeof(*bdev));
   		mutex_init(&bdev->bd_mutex);
--		mutex_init(&bdev->bd_mount_mutex);
-+		sema_init(&bdev->bd_mount_sem, 1);
++		INIT_MOUNT_SEMUTEX(bdev);
   		INIT_LIST_HEAD(&bdev->bd_inodes);
   		INIT_LIST_HEAD(&bdev->bd_list);
   #ifdef CONFIG_SYSFS
----------------------------------------------------------------------
   {
   	struct super_block *sb;

--	mutex_lock(&bdev->bd_mount_mutex);
-+	down(&bdev->bd_mount_sem);
++	LOCK_MOUNT_SEMUTEX(bdev);
   	sb = get_super(bdev);
   	if (sb && !(sb->s_flags & MS_RDONLY)) {
   		sb->s_frozen = SB_FREEZE_WRITE;
----------------------------------------------------------------------
   		drop_super(sb);
   	}

--	mutex_unlock(&bdev->bd_mount_mutex);
-+	up(&bdev->bd_mount_sem);
++	UNLOCK_MOUNT_SEMUTEX(bdev);
   }
   EXPORT_SYMBOL(thaw_bdev);

----------------------------------------------------------------------
   	 * will protect the lockfs code from trying to start a snapshot
   	 * while we are mounting
   	 */
--	mutex_lock(&bdev->bd_mount_mutex);
-+	down(&bdev->bd_mount_sem);
++	LOCK_MOUNT_SEMUTEX(bdev);
   	s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
--	mutex_unlock(&bdev->bd_mount_mutex);
-+	up(&bdev->bd_mount_sem);
++	UNLOCK_MOUNT_SEMUTEX(bdev);
   	if (IS_ERR(s))
   		goto error_s;

----------------------------------------------------------------------
   	struct inode *		bd_inode;	/* will die */
   	int			bd_openers;
   	struct mutex		bd_mutex;	/* open/close mutex */
--	struct mutex		bd_mount_mutex;	/* mount mutex */
-+	struct semaphore        bd_mount_sem;
++#ifdef MOUNT_SEMUTEX_IS_MUTEX
++	struct mutex		bd_mount_mutex;	/* mount mutex */
++#endif
++#ifdef MOUNT_SEMUTEX_IS_SEMAPHORE
++	struct semaphore        bd_mount_sem;
++#endif
   	struct list_head	bd_inodes;
   	void *			bd_holder;
   	int			bd_holders;
----------------------------------------------------------------------
The End.
2007-01-03T06:20:00+0000 foma at pc.somewhere.over.the.ru

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