move virtrng_remove to .devexit.text
[linux-2.6.git] / fs / block_dev.c
index 3a6d4fb..9cf4b92 100644 (file)
@@ -216,8 +216,6 @@ EXPORT_SYMBOL(fsync_bdev);
  * freeze_bdev  --  lock a filesystem and force it into a consistent state
  * @bdev:      blockdevice to lock
  *
- * This takes the block device bd_mount_sem to make sure no new mounts
- * happen on bdev until thaw_bdev() is called.
  * If a superblock is found on this device, we take the s_umount semaphore
  * on it to make sure nobody unmounts until the snapshot creation is done.
  * The reference counter (bd_fsfreeze_count) guarantees that only the last
@@ -232,46 +230,55 @@ struct super_block *freeze_bdev(struct block_device *bdev)
        int error = 0;
 
        mutex_lock(&bdev->bd_fsfreeze_mutex);
-       if (bdev->bd_fsfreeze_count > 0) {
-               bdev->bd_fsfreeze_count++;
+       if (++bdev->bd_fsfreeze_count > 1) {
+               /*
+                * We don't even need to grab a reference - the first call
+                * to freeze_bdev grab an active reference and only the last
+                * thaw_bdev drops it.
+                */
                sb = get_super(bdev);
+               drop_super(sb);
                mutex_unlock(&bdev->bd_fsfreeze_mutex);
                return sb;
        }
-       bdev->bd_fsfreeze_count++;
-
-       down(&bdev->bd_mount_sem);
-       sb = get_super(bdev);
-       if (sb && !(sb->s_flags & MS_RDONLY)) {
-               sb->s_frozen = SB_FREEZE_WRITE;
-               smp_wmb();
-
-               sync_filesystem(sb);
-
-               sb->s_frozen = SB_FREEZE_TRANS;
-               smp_wmb();
-
-               sync_blockdev(sb->s_bdev);
-
-               if (sb->s_op->freeze_fs) {
-                       error = sb->s_op->freeze_fs(sb);
-                       if (error) {
-                               printk(KERN_ERR
-                                       "VFS:Filesystem freeze failed\n");
-                               sb->s_frozen = SB_UNFROZEN;
-                               drop_super(sb);
-                               up(&bdev->bd_mount_sem);
-                               bdev->bd_fsfreeze_count--;
-                               mutex_unlock(&bdev->bd_fsfreeze_mutex);
-                               return ERR_PTR(error);
-                       }
+
+       sb = get_active_super(bdev);
+       if (!sb)
+               goto out;
+       if (sb->s_flags & MS_RDONLY) {
+               deactivate_locked_super(sb);
+               mutex_unlock(&bdev->bd_fsfreeze_mutex);
+               return sb;
+       }
+
+       sb->s_frozen = SB_FREEZE_WRITE;
+       smp_wmb();
+
+       sync_filesystem(sb);
+
+       sb->s_frozen = SB_FREEZE_TRANS;
+       smp_wmb();
+
+       sync_blockdev(sb->s_bdev);
+
+       if (sb->s_op->freeze_fs) {
+               error = sb->s_op->freeze_fs(sb);
+               if (error) {
+                       printk(KERN_ERR
+                               "VFS:Filesystem freeze failed\n");
+                       sb->s_frozen = SB_UNFROZEN;
+                       deactivate_locked_super(sb);
+                       bdev->bd_fsfreeze_count--;
+                       mutex_unlock(&bdev->bd_fsfreeze_mutex);
+                       return ERR_PTR(error);
                }
        }
+       up_write(&sb->s_umount);
 
+ out:
        sync_blockdev(bdev);
        mutex_unlock(&bdev->bd_fsfreeze_mutex);
-
-       return sb;      /* thaw_bdev releases s->s_umount and bd_mount_sem */
+       return sb;      /* thaw_bdev releases s->s_umount */
 }
 EXPORT_SYMBOL(freeze_bdev);
 
@@ -284,44 +291,44 @@ EXPORT_SYMBOL(freeze_bdev);
  */
 int thaw_bdev(struct block_device *bdev, struct super_block *sb)
 {
-       int error = 0;
+       int error = -EINVAL;
 
        mutex_lock(&bdev->bd_fsfreeze_mutex);
-       if (!bdev->bd_fsfreeze_count) {
-               mutex_unlock(&bdev->bd_fsfreeze_mutex);
-               return -EINVAL;
-       }
-
-       bdev->bd_fsfreeze_count--;
-       if (bdev->bd_fsfreeze_count > 0) {
-               if (sb)
-                       drop_super(sb);
-               mutex_unlock(&bdev->bd_fsfreeze_mutex);
-               return 0;
-       }
-
-       if (sb) {
-               BUG_ON(sb->s_bdev != bdev);
-               if (!(sb->s_flags & MS_RDONLY)) {
-                       if (sb->s_op->unfreeze_fs) {
-                               error = sb->s_op->unfreeze_fs(sb);
-                               if (error) {
-                                       printk(KERN_ERR
-                                               "VFS:Filesystem thaw failed\n");
-                                       sb->s_frozen = SB_FREEZE_TRANS;
-                                       bdev->bd_fsfreeze_count++;
-                                       mutex_unlock(&bdev->bd_fsfreeze_mutex);
-                                       return error;
-                               }
-                       }
-                       sb->s_frozen = SB_UNFROZEN;
-                       smp_wmb();
-                       wake_up(&sb->s_wait_unfrozen);
+       if (!bdev->bd_fsfreeze_count)
+               goto out_unlock;
+
+       error = 0;
+       if (--bdev->bd_fsfreeze_count > 0)
+               goto out_unlock;
+
+       if (!sb)
+               goto out_unlock;
+
+       BUG_ON(sb->s_bdev != bdev);
+       down_write(&sb->s_umount);
+       if (sb->s_flags & MS_RDONLY)
+               goto out_deactivate;
+
+       if (sb->s_op->unfreeze_fs) {
+               error = sb->s_op->unfreeze_fs(sb);
+               if (error) {
+                       printk(KERN_ERR
+                               "VFS:Filesystem thaw failed\n");
+                       sb->s_frozen = SB_FREEZE_TRANS;
+                       bdev->bd_fsfreeze_count++;
+                       mutex_unlock(&bdev->bd_fsfreeze_mutex);
+                       return error;
                }
-               drop_super(sb);
        }
 
-       up(&bdev->bd_mount_sem);
+       sb->s_frozen = SB_UNFROZEN;
+       smp_wmb();
+       wake_up(&sb->s_wait_unfrozen);
+
+out_deactivate:
+       if (sb)
+               deactivate_locked_super(sb);
+out_unlock:
        mutex_unlock(&bdev->bd_fsfreeze_mutex);
        return 0;
 }
@@ -420,7 +427,6 @@ static void bdev_destroy_inode(struct inode *inode)
 {
        struct bdev_inode *bdi = BDEV_I(inode);
 
-       bdi->bdev.bd_inode_backing_dev_info = NULL;
        kmem_cache_free(bdev_cachep, bdi);
 }
 
@@ -431,7 +437,6 @@ static void init_once(void *foo)
 
        memset(bdev, 0, sizeof(*bdev));
        mutex_init(&bdev->bd_mutex);
-       sema_init(&bdev->bd_mount_sem, 1);
        INIT_LIST_HEAD(&bdev->bd_inodes);
        INIT_LIST_HEAD(&bdev->bd_list);
 #ifdef CONFIG_SYSFS
@@ -564,6 +569,16 @@ struct block_device *bdget(dev_t dev)
 
 EXPORT_SYMBOL(bdget);
 
+/**
+ * bdgrab -- Grab a reference to an already referenced block device
+ * @bdev:      Block device to grab a reference to.
+ */
+struct block_device *bdgrab(struct block_device *bdev)
+{
+       atomic_inc(&bdev->bd_inode->i_count);
+       return bdev;
+}
+
 long nr_blockdev_pages(void)
 {
        struct block_device *bdev;
@@ -1105,7 +1120,7 @@ EXPORT_SYMBOL(revalidate_disk);
 int check_disk_change(struct block_device *bdev)
 {
        struct gendisk *disk = bdev->bd_disk;
-       struct block_device_operations * bdops = disk->fops;
+       const struct block_device_operations *bdops = disk->fops;
 
        if (!bdops->media_changed)
                return 0;
@@ -1395,6 +1410,33 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 }
 
 /*
+ * Write data to the block device.  Only intended for the block device itself
+ * and the raw driver which basically is a fake block device.
+ *
+ * Does not take i_mutex for the write and thus is not for general purpose
+ * use.
+ */
+ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
+                        unsigned long nr_segs, loff_t pos)
+{
+       struct file *file = iocb->ki_filp;
+       ssize_t ret;
+
+       BUG_ON(iocb->ki_pos != pos);
+
+       ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
+       if (ret > 0 || ret == -EIOCBQUEUED) {
+               ssize_t err;
+
+               err = generic_write_sync(file, pos, ret);
+               if (err < 0 && ret > 0)
+                       ret = err;
+       }
+       return ret;
+}
+EXPORT_SYMBOL_GPL(blkdev_aio_write);
+
+/*
  * Try to release a page associated with block device when the system
  * is under memory pressure.
  */
@@ -1426,7 +1468,7 @@ const struct file_operations def_blk_fops = {
        .read           = do_sync_read,
        .write          = do_sync_write,
        .aio_read       = generic_file_aio_read,
-       .aio_write      = generic_file_aio_write_nolock,
+       .aio_write      = blkdev_aio_write,
        .mmap           = generic_file_mmap,
        .fsync          = block_fsync,
        .unlocked_ioctl = block_ioctl,