[PATCH 8/8] block: remove bdget_disk

Christoph Hellwig
2021-05-25T06:13:40Z

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 e3de476797de..2abafe44bf4b 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -692,32 +692,6 @@ 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
@@ -1244,13 +1218,14 @@ 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 0d33f55a7d78..325368b9de29 100644
--- a/block/partitions/core.c
+++ b/block/partitions/core.c
@@ -325,6 +325,8 @@ static struct block_device *add_partition(struct gendisk *disk, int partno,
const char *dname;
int err;

+ lockdep_assert_held(&disk->open_mutex);
+
/*
* disk_max_parts() won't be zero, either GENHD_FL_EXT_DEVT is set
* or 'minors' is passed to alloc_disk().
@@ -464,14 +466,13 @@ 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)
@@ -481,21 +482,20 @@ 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;
@@ -509,7 +509,6 @@ 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 96d55cd06cf6..d06892a0a9ef 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -222,7 +222,6 @@ 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);

--
2.30.2