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

[Christoph Hellwig <hch@xxxxxx>]

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@xxxxxx>
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
---
 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 b9ee8fe5acd570..e8d7de5fae00a9 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)
@@ -879,7 +879,6 @@ 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;
@@ -1342,9 +1341,7 @@ 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)
@@ -1384,7 +1381,6 @@ 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 (!bdev->bd_part || !bdev->bd_part->nr_sects) {
                                __blkdev_put(whole, mode, 1);
@@ -1398,7 +1394,7 @@ 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);
@@ -1416,7 +1412,6 @@ 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;
 }
 
@@ -1659,8 +1654,7 @@ 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);
@@ -1678,6 +1672,7 @@ 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;
 
                /*
@@ -1688,13 +1683,12 @@ 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