[PATCH 15/15] block: remove bdget_disk

From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>, Song Liu <song@kernel.org>
Cc: "Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>,
	"Minchan Kim" <minchan@kernel.org>,
	"Nitin Gupta" <ngupta@vflare.org>,
	"Stefan Haberland" <sth@linux.ibm.com>,
	"Jan Hoeppner" <hoeppner@linux.ibm.com>,
	linux-block@vger.kernel.org, linux-raid@vger.kernel.org,
	linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org
Subject: [PATCH 15/15] block: remove bdget_disk
Date: Tue, 30 Mar 2021 18:17:27 +0200	[thread overview]
Message-ID: <20210330161727.2297292-16-hch@lst.de> (raw)
In-Reply-To: <20210330161727.2297292-1-hch@lst.de>

Just opencode the xa_load in the callers, as none of them actually
needs a reference to the bdev.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/genhd.c           | 35 +++++------------------------------
 block/partitions/core.c | 25 ++++++++++++-------------
 include/linux/genhd.h   |  1 -
 3 files changed, 17 insertions(+), 44 deletions(-)

diff --git a/block/genhd.c b/block/genhd.c
index 232c8420b04973..f0d4cf80dac1ea 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -778,32 +778,6 @@ void blk_request_module(dev_t devt)
 		request_module("block-major-%d", MAJOR(devt));
 }
 
-/**
- * bdget_disk - do bdget() by gendisk and partition number
- * @disk: gendisk of interest
- * @partno: partition number
- *
- * Find partition @partno from @disk, do bdget() on it.
- *
- * CONTEXT:
- * Don't care.
- *
- * RETURNS:
- * Resulting block_device on success, NULL on failure.
- */
-struct block_device *bdget_disk(struct gendisk *disk, int partno)
-{
-	struct block_device *bdev = NULL;
-
-	rcu_read_lock();
-	bdev = xa_load(&disk->part_tbl, partno);
-	if (bdev && !bdgrab(bdev))
-		bdev = NULL;
-	rcu_read_unlock();
-
-	return bdev;
-}
-
 /*
  * print a full list of all partitions - intended for places where the root
  * filesystem can't be mounted and thus to give the victim some idea of what
@@ -1328,13 +1302,14 @@ module_init(proc_genhd_init);
 
 dev_t part_devt(struct gendisk *disk, u8 partno)
 {
-	struct block_device *part = bdget_disk(disk, partno);
+	struct block_device *part;
 	dev_t devt = 0;
 
-	if (part) {
+	rcu_read_lock();
+	part = xa_load(&disk->part_tbl, partno);
+	if (part)
 		devt = part->bd_dev;
-		bdput(part);
-	}
+	rcu_read_unlock();
 
 	return devt;
 }
diff --git a/block/partitions/core.c b/block/partitions/core.c
index 162b9b35c53171..00e425c668a5f8 100644
--- a/block/partitions/core.c
+++ b/block/partitions/core.c
@@ -322,6 +322,8 @@ static struct block_device *add_partition(struct gendisk *disk, int partno,
 	const char *dname;
 	int err;
 
+	lockdep_assert_held(&disk->open_mutex);
+
 	/*
 	 * Partitions are not supported on zoned block devices that are used as
 	 * such.
@@ -454,14 +456,13 @@ int bdev_add_partition(struct block_device *bdev, int partno,
 
 int bdev_del_partition(struct block_device *bdev, int partno)
 {
-	struct block_device *part;
-	int ret;
-
-	part = bdget_disk(bdev->bd_disk, partno);
-	if (!part)
-		return -ENXIO;
+	struct block_device *part = NULL;
+	int ret = -ENXIO;
 
 	mutex_lock(&bdev->bd_disk->open_mutex);
+	part = xa_load(&bdev->bd_disk->part_tbl, partno);
+	if (!part)
+		goto out_unlock;
 
 	ret = -EBUSY;
 	if (part->bd_openers)
@@ -474,21 +475,20 @@ int bdev_del_partition(struct block_device *bdev, int partno)
 	ret = 0;
 out_unlock:
 	mutex_unlock(&bdev->bd_disk->open_mutex);
-	bdput(part);
 	return ret;
 }
 
 int bdev_resize_partition(struct block_device *bdev, int partno,
 		sector_t start, sector_t length)
 {
-	struct block_device *part;
-	int ret = 0;
+	struct block_device *part = NULL;
+	int ret = -ENXIO;
 
-	part = bdget_disk(bdev->bd_disk, partno);
+	mutex_lock(&bdev->bd_disk->open_mutex);
+	part = xa_load(&bdev->bd_disk->part_tbl, partno);
 	if (!part)
-		return -ENXIO;
+		goto out_unlock;
 
-	mutex_lock(&bdev->bd_disk->open_mutex);
 	ret = -EINVAL;
 	if (start != part->bd_start_sect)
 		goto out_unlock;
@@ -502,7 +502,6 @@ int bdev_resize_partition(struct block_device *bdev, int partno,
 	ret = 0;
 out_unlock:
 	mutex_unlock(&bdev->bd_disk->open_mutex);
-	bdput(part);
 	return ret;
 }
 
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 819366811349eb..674fc0761105bc 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -241,7 +241,6 @@ static inline void add_disk_no_queue_reg(struct gendisk *disk)
 }
 
 extern void del_gendisk(struct gendisk *gp);
-extern struct block_device *bdget_disk(struct gendisk *disk, int partno);
 
 void set_disk_ro(struct gendisk *disk, bool read_only);
 
-- 
2.30.1

