[PATCH] block: Fix register_disk() when name has '/' in it

[Roland Dreier <rdreier@cisco.com>]

Commit 3ada8b7e ("block: struct device - replace bus_id with dev_name(),
dev_set_name()") deleted the code in register_disk() that changed a '/'
to a '!' in the device name when registering a disk.  This leads to
amusing problems with disks that have '/' in their names -- for example
a failure to boot with the root partition on a cciss device, even though
the kernel says it knows about the root device:

    VFS: Cannot open root device "cciss/c0d0p6" or unknown-block(0,0)
    Please append a correct "root=" boot option; here are the available partitions:
    6800        71652960 cciss/c0d0 driver: cciss
      6802               1 cciss/c0d0p2
      6805         2931831 cciss/c0d0p5
      6806        34354908 cciss/c0d0p6
    6810        71652960 cciss/c0d1 driver: cciss

Fix this by bringing back the code to change '/' to '!' in disk names
when registering a disk.

Signed-off-by: Roland Dreier <rolandd@cisco.com>
---
 fs/partitions/check.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index 6d72024..474d73e 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -448,11 +448,19 @@ void register_disk(struct gendisk *disk)
 	struct block_device *bdev;
 	struct disk_part_iter piter;
 	struct hd_struct *part;
+	char dname[DISK_NAME_LEN];
+	char *s;
 	int err;
 
 	ddev->parent = disk->driverfs_dev;
 
-	dev_set_name(ddev, disk->disk_name);
+	/* ewww... some of these buggers have / in the name... */
+	strcpy(dname, disk->disk_name);
+	s = strchr(dname, '/');
+	if (s)
+		*s = '!';
+
+	dev_set_name(ddev, dname);
 
 	/* delay uevents, until we scanned partition table */
 	ddev->uevent_suppress = 1;