[PATCH 14/21] block: mark underlying cdev with DEVFS_IS_BLOCK_DEV

[Ahmad Fatoum]

When given a cdev, we detect whether it's a block device by testing that
its ops are those of a block device.

This has the downside that any block device must use the block caching layer.
ramdisks don't benefit from the caching though, so let's add a new flag
bit to mark block devices and use it in preparation for adding ramdisk
support.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 common/block.c   |  9 +--------
 include/block.h  | 13 +++++++------
 include/driver.h |  1 +
 3 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/common/block.c b/common/block.c
index d401e979abff..ca2ed37dbd3e 100644
--- a/common/block.c
+++ b/common/block.c
@@ -447,14 +447,6 @@ static struct cdev_operations block_ops = {
 	.discard_range = block_op_discard_range,
 };
 
-struct block_device *cdev_get_block_device(const struct cdev *cdev)
-{
-	if (!cdev || cdev->ops != &block_ops)
-		return NULL;
-
-	return cdev->priv;
-}
-
 int blockdevice_register(struct block_device *blk)
 {
 	loff_t size = (loff_t)blk->num_blocks * BLOCKSIZE(blk);
@@ -465,6 +457,7 @@ int blockdevice_register(struct block_device *blk)
 	blk->cdev.dev = blk->dev;
 	blk->cdev.ops = &block_ops;
 	blk->cdev.priv = blk;
+	blk->cdev.flags |= DEVFS_IS_BLOCK_DEV;
 	blk->rdbufsize = BUFSIZE >> blk->blockbits;
 
 	INIT_LIST_HEAD(&blk->buffered_blocks);
diff --git a/include/block.h b/include/block.h
index 5ce3eb7d7838..73b305cdb03f 100644
--- a/include/block.h
+++ b/include/block.h
@@ -82,14 +82,9 @@ static inline int block_flush(struct block_device *blk)
 }
 
 #ifdef CONFIG_BLOCK
-struct block_device *cdev_get_block_device(const struct cdev *cdev);
 unsigned file_list_add_blockdevs(struct file_list *files);
 char *cdev_get_linux_rootarg(const struct cdev *partcdev);
 #else
-static inline struct block_device *cdev_get_block_device(const struct cdev *cdev)
-{
-	return NULL;
-}
 static inline unsigned file_list_add_blockdevs(struct file_list *files)
 {
 	return 0;
@@ -102,7 +97,8 @@ static inline char *cdev_get_linux_rootarg(const struct cdev *partcdev)
 
 static inline bool cdev_is_block_device(const struct cdev *cdev)
 {
-	return cdev_get_block_device(cdev) != NULL;
+	return IS_ENABLED(CONFIG_BLOCK) && cdev &&
+		(cdev->flags & DEVFS_IS_BLOCK_DEV);
 }
 
 static inline bool cdev_is_block_partition(const struct cdev *cdev)
@@ -116,4 +112,9 @@ static inline bool cdev_is_block_disk(const struct cdev *cdev)
 	return cdev_is_block_device(cdev) && !cdev_is_partition(cdev);
 }
 
+static inline struct block_device *cdev_get_block_device(const struct cdev *cdev)
+{
+	return cdev_is_block_device(cdev) ? cdev->priv : NULL;
+}
+
 #endif /* __BLOCK_H */
diff --git a/include/driver.h b/include/driver.h
index e9a919f9bbb5..41e5dad724c3 100644
--- a/include/driver.h
+++ b/include/driver.h
@@ -581,6 +581,7 @@ extern struct list_head cdev_list;
 #define DEVFS_PARTITION_FIXED		(1U << 0)
 #define DEVFS_PARTITION_READONLY	(1U << 1)
 #define DEVFS_IS_CHARACTER_DEV		(1U << 3)
+#define DEVFS_IS_BLOCK_DEV		(1U << 4)
 #define DEVFS_PARTITION_FROM_OF		(1U << 5)
 #define DEVFS_PARTITION_FROM_TABLE	(1U << 6)
 #define DEVFS_IS_MBR_PARTITIONED	(1U << 7)
-- 
2.39.5