[RFC PATCH 1/2] block: embed bdevname in struct block_device

[Yuanhan Liu <yuanhan.liu@linux.intel.com>]

Embed block device name in struct block_device, thus we can replace
the following code:
	char b[BDEVNAME_SIZE];
	printk(KERN_XXX "...%s..\n", bdevname(bdev, b);

with a much simpler and less stack usage version:
	printk(KERN_XXX "...%s..\n", bdev->bd_name);

This is a RFC version, which I just included one sample with this change
appiled. If this patch makes sense to you, I will file more patches to
apply this change.

Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
---
 fs/block_dev.c     |    2 ++
 include/linux/fs.h |    3 ++-
 2 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 1e51919..5e796e58 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1213,6 +1213,8 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
 			}
 			bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
 		}
+
+		disk_name(bdev->bd_disk, bdev->bd_part->partno, bdev->bd_name);
 	} else {
 		if (bdev->bd_contains == bdev) {
 			ret = 0;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index aa11047..98ea89d 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -689,6 +689,7 @@ struct address_space {
 	 */
 struct request_queue;
 
+#define BDEVNAME_SIZE	32	/* Largest string for a blockdev identifier */
 struct block_device {
 	dev_t			bd_dev;  /* not a kdev_t - it's a search key */
 	int			bd_openers;
@@ -724,6 +725,7 @@ struct block_device {
 	int			bd_fsfreeze_count;
 	/* Mutex for freeze */
 	struct mutex		bd_fsfreeze_mutex;
+	char 			bd_name[BDEVNAME_SIZE];
 };
 
 /*
@@ -2323,7 +2325,6 @@ static inline void unregister_chrdev(unsigned int major, const char *name)
 }
 
 /* fs/block_dev.c */
-#define BDEVNAME_SIZE	32	/* Largest string for a blockdev identifier */
 #define BDEVT_SIZE	10	/* Largest string for MAJ:MIN for blkdev */
 
 #ifdef CONFIG_BLOCK
-- 
1.7.7.6