[PATCH 16/20] block: stop using bdget_disk for partition 0

[Christoph Hellwig <hch@lst.de>]

We can just dereference the point in struct gendisk instead.  Also
remove the now unused export.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/genhd.c                   |  1 -
 drivers/block/nbd.c             |  4 +---
 drivers/block/xen-blkfront.c    | 20 +++++---------------
 drivers/block/zram/zram_drv.c   | 18 +++---------------
 drivers/md/dm.c                 |  8 +-------
 drivers/s390/block/dasd_ioctl.c |  5 ++---
 6 files changed, 12 insertions(+), 44 deletions(-)

diff --git a/block/genhd.c b/block/genhd.c
index a14e2408e3d4e8..ec41d0f18f5ce1 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -907,7 +907,6 @@ struct block_device *bdget_disk(struct gendisk *disk, int partno)
 
 	return bdev;
 }
-EXPORT_SYMBOL(bdget_disk);
 
 /*
  * print a full list of all partitions - intended for places where the root
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 014683968ce174..92f84ed0ba9eb6 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1488,12 +1488,10 @@ static int nbd_open(struct block_device *bdev, fmode_t mode)
 static void nbd_release(struct gendisk *disk, fmode_t mode)
 {
 	struct nbd_device *nbd = disk->private_data;
-	struct block_device *bdev = bdget_disk(disk, 0);
 
 	if (test_bit(NBD_RT_DISCONNECT_ON_CLOSE, &nbd->config->runtime_flags) &&
-			bdev->bd_openers == 0)
+			disk->part0->bd_openers == 0)
 		nbd_disconnect_and_put(nbd);
-	bdput(bdev);
 
 	nbd_config_put(nbd);
 	nbd_put(nbd);
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 79521e33d30ed5..188e0b47534bcf 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -2153,7 +2153,7 @@ static void blkfront_closing(struct blkfront_info *info)
 	}
 
 	if (info->gd)
-		bdev = bdget_disk(info->gd, 0);
+		bdev = bdgrab(info->gd->part0);
 
 	mutex_unlock(&info->mutex);
 
@@ -2518,7 +2518,7 @@ static int blkfront_remove(struct xenbus_device *xbdev)
 
 	disk = info->gd;
 	if (disk)
-		bdev = bdget_disk(disk, 0);
+		bdev = bdgrab(disk->part0);
 
 	info->xbdev = NULL;
 	mutex_unlock(&info->mutex);
@@ -2595,19 +2595,11 @@ static int blkif_open(struct block_device *bdev, fmode_t mode)
 static void blkif_release(struct gendisk *disk, fmode_t mode)
 {
 	struct blkfront_info *info = disk->private_data;
-	struct block_device *bdev;
 	struct xenbus_device *xbdev;
 
 	mutex_lock(&blkfront_mutex);
-
-	bdev = bdget_disk(disk, 0);
-
-	if (!bdev) {
-		WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
+	if (disk->part0->bd_openers)
 		goto out_mutex;
-	}
-	if (bdev->bd_openers)
-		goto out;
 
 	/*
 	 * Check if we have been instructed to close. We will have
@@ -2619,7 +2611,7 @@ static void blkif_release(struct gendisk *disk, fmode_t mode)
 
 	if (xbdev && xbdev->state == XenbusStateClosing) {
 		/* pending switch to state closed */
-		dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
+		dev_info(disk_to_dev(disk), "releasing disk\n");
 		xlvbd_release_gendisk(info);
 		xenbus_frontend_closed(info->xbdev);
  	}
@@ -2628,14 +2620,12 @@ static void blkif_release(struct gendisk *disk, fmode_t mode)
 
 	if (!xbdev) {
 		/* sudden device removal */
-		dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
+		dev_info(disk_to_dev(disk), "releasing disk\n");
 		xlvbd_release_gendisk(info);
 		disk->private_data = NULL;
 		free_info(info);
 	}
 
-out:
-	bdput(bdev);
 out_mutex:
 	mutex_unlock(&blkfront_mutex);
 }
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 01757f9578dcb8..56024905bd242c 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1748,7 +1748,7 @@ static ssize_t reset_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t len)
 {
 	struct zram *zram = dev_to_zram(dev);
-	struct block_device *bdev;
+	struct block_device *bdev = zram->disk->part0;
 	unsigned short do_reset;
 	int ret = 0;
 
@@ -1758,17 +1758,12 @@ static ssize_t reset_store(struct device *dev,
 	if (!do_reset)
 		return -EINVAL;
 
-	bdev = bdget_disk(zram->disk, 0);
-	if (!bdev)
-		return -ENOMEM;
-
 	mutex_lock(&bdev->bd_mutex);
 	if (bdev->bd_openers)
 		ret = -EBUSY;
 	else
 		zram_reset_device(zram);
 	mutex_unlock(&bdev->bd_mutex);
-	bdput(bdev);
 
 	return ret ? ret : len;
 }
@@ -1933,15 +1928,8 @@ static int zram_add(void)
 
 static int zram_remove(struct zram *zram)
 {
-	struct block_device *bdev = bdget_disk(zram->disk, 0);
-
-	if (bdev) {
-		if (bdev->bd_openers) {
-			bdput(bdev);
-			return -EBUSY;
-		}
-		bdput(bdev);
-	}
+	if (zram->disk->part0->bd_openers)
+		return -EBUSY;
 
 	del_gendisk(zram->disk);
 	zram_debugfs_unregister(zram);
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index c9438feefe55a3..ec48ccae50dd53 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2375,17 +2375,12 @@ struct dm_table *dm_swap_table(struct mapped_device *md, struct dm_table *table)
  */
 static int lock_fs(struct mapped_device *md)
 {
-	struct block_device *bdev;
 	int r;
 
 	WARN_ON(md->frozen_sb);
 
-	bdev = bdget_disk(md->disk, 0);
-	if (!bdev)
-		return -ENOMEM;
-	md->frozen_sb = freeze_bdev(bdev);
+	md->frozen_sb = freeze_bdev(md->disk->part0);
 	if (IS_ERR(md->frozen_sb)) {
-		bdput(bdev);
 		r = PTR_ERR(md->frozen_sb);
 		md->frozen_sb = NULL;
 		return r;
@@ -2402,7 +2397,6 @@ static void unlock_fs(struct mapped_device *md)
 		return;
 
 	thaw_bdev(md->frozen_sb->s_bdev, md->frozen_sb);
-	bdput(md->frozen_sb->s_bdev);
 	md->frozen_sb = NULL;
 	clear_bit(DMF_FROZEN, &md->flags);
 }
diff --git a/drivers/s390/block/dasd_ioctl.c b/drivers/s390/block/dasd_ioctl.c
index 304eba1acf163c..9f642440894655 100644
--- a/drivers/s390/block/dasd_ioctl.c
+++ b/drivers/s390/block/dasd_ioctl.c
@@ -220,9 +220,8 @@ dasd_format(struct dasd_block *block, struct format_data_t *fdata)
 	 * enabling the device later.
 	 */
 	if (fdata->start_unit == 0) {
-		struct block_device *bdev = bdget_disk(block->gdp, 0);
-		bdev->bd_inode->i_blkbits = blksize_bits(fdata->blksize);
-		bdput(bdev);
+		block->gdp->part0->bd_inode->i_blkbits =
+			blksize_bits(fdata->blksize);
 	}
 
 	rc = base->discipline->format_device(base, fdata, 1);
-- 
2.29.2