[PATCH 26/45] block: remove ->bd_contains

Christoph Hellwig
2020-11-28T22:12:04Z

Now that each hd_struct has a reference to the corresponding
block_device, there is no need for the bd_contains pointer. Add
a bdev_whole() helper to look up the whole device block_device
struture instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
---
drivers/block/loop.c | 2 +-
drivers/scsi/scsicam.c | 2 +-
fs/block_dev.c | 22 ++++++++--------------
include/linux/blk_types.h | 4 +++-
4 files changed, 13 insertions(+), 17 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 26c7aafba7c5f8..c0df88b3300c41 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1088,7 +1088,7 @@ static int loop_configure(struct loop_device *lo, fmode_t mode,
* here to avoid changing device under exclusive owner.
*/
if (!(mode & FMODE_EXCL)) {
- claimed_bdev = bdev->bd_contains;
+ claimed_bdev = bdev_whole(bdev);
error = bd_prepare_to_claim(bdev, claimed_bdev, loop_configure);
if (error)
goto out_putf;
diff --git a/drivers/scsi/scsicam.c b/drivers/scsi/scsicam.c
index 682cf08ab04153..f1553a453616fd 100644
--- a/drivers/scsi/scsicam.c
+++ b/drivers/scsi/scsicam.c
@@ -32,7 +32,7 @@
*/
unsigned char *scsi_bios_ptable(struct block_device *dev)
{
- struct address_space *mapping = dev->bd_contains->bd_inode->i_mapping;
+ struct address_space *mapping = bdev_whole(dev)->bd_inode->i_mapping;
unsigned char *res = NULL;
struct page *page;

diff --git a/fs/block_dev.c b/fs/block_dev.c
index b350ed3af83bad..94baee369d26e5 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -119,7 +119,7 @@ int truncate_bdev_range(struct block_device *bdev, fmode_t mode,
* under live filesystem.
*/
if (!(mode & FMODE_EXCL)) {
- claimed_bdev = bdev->bd_contains;
+ claimed_bdev = bdev_whole(bdev);
err = bd_prepare_to_claim(bdev, claimed_bdev,
truncate_bdev_range);
if (err)
@@ -880,7 +880,6 @@ struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
spin_lock_init(&bdev->bd_size_lock);
bdev->bd_disk = disk;
bdev->bd_partno = partno;
- bdev->bd_contains = NULL;
bdev->bd_super = NULL;
bdev->bd_inode = inode;
bdev->bd_part_count = 0;
@@ -1347,9 +1346,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode)
int ret;

if (!bdev->bd_openers) {
- bdev->bd_contains = bdev;
-
- if (!bdev->bd_partno) {
+ if (!bdev_is_partition(bdev)) {
ret = -ENXIO;
bdev->bd_part = disk_get_part(disk, 0);
if (!bdev->bd_part)
@@ -1389,7 +1386,6 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode)
whole->bd_part_count++;
mutex_unlock(&whole->bd_mutex);

- bdev->bd_contains = whole;
bdev->bd_part = disk_get_part(disk, bdev->bd_partno);
if (!(disk->flags & GENHD_FL_UP) ||
!bdev->bd_part || !bdev->bd_part->nr_sects) {
@@ -1405,7 +1401,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode)
if (bdev->bd_bdi == &noop_backing_dev_info)
bdev->bd_bdi = bdi_get(disk->queue->backing_dev_info);
} else {
- if (bdev->bd_contains == bdev) {
+ if (!bdev_is_partition(bdev)) {
ret = 0;
if (bdev->bd_disk->fops->open)
ret = bdev->bd_disk->fops->open(bdev, mode);
@@ -1423,7 +1419,6 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode)
out_clear:
disk_put_part(bdev->bd_part);
bdev->bd_part = NULL;
- bdev->bd_contains = NULL;
return ret;
}

@@ -1670,8 +1665,7 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
disk_put_part(bdev->bd_part);
bdev->bd_part = NULL;
if (bdev_is_partition(bdev))
- victim = bdev->bd_contains;
- bdev->bd_contains = NULL;
+ victim = bdev_whole(bdev);
} else {
if (!bdev_is_partition(bdev) && disk->fops->release)
disk->fops->release(disk, mode);
@@ -1690,6 +1684,7 @@ void blkdev_put(struct block_device *bdev, fmode_t mode)
mutex_lock(&bdev->bd_mutex);

if (mode & FMODE_EXCL) {
+ struct block_device *whole = bdev_whole(bdev);
bool bdev_free;

/*
@@ -1700,13 +1695,12 @@ void blkdev_put(struct block_device *bdev, fmode_t mode)
spin_lock(&bdev_lock);

WARN_ON_ONCE(--bdev->bd_holders < 0);
- WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0);
+ WARN_ON_ONCE(--whole->bd_holders < 0);

- /* bd_contains might point to self, check in a separate step */
if ((bdev_free = !bdev->bd_holders))
bdev->bd_holder = NULL;
- if (!bdev->bd_contains->bd_holders)
- bdev->bd_contains->bd_holder = NULL;
+ if (!whole->bd_holders)
+ whole->bd_holder = NULL;

spin_unlock(&bdev_lock);

diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 9698f459cc65c9..2e0a9bd9688d28 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -32,7 +32,6 @@ struct block_device {
#ifdef CONFIG_SYSFS
struct list_head bd_holder_disks;
#endif
- struct block_device * bd_contains;
u8 bd_partno;
struct hd_struct * bd_part;
/* number of times partitions within this device have been opened. */
@@ -49,6 +48,9 @@ struct block_device {
struct super_block *bd_fsfreeze_sb;
} __randomize_layout;

+#define bdev_whole(_bdev) \
+ ((_bdev)->bd_disk->part0.bdev)
+
#define bdev_kobj(_bdev) \
(&part_to_dev((_bdev)->bd_part)->kobj)

--
2.29.2