Fix incorrect Mt Rainier detection

cdrom_is_mrw() can incorrectly think that a drive is Mt Rainier capable, because if forgets to check if the "GET CONFIGURATION" command returns the MRW feature number. According to the MMC spec, the drive shall return all feature numbers >= the starting feature number, so even if the drive doesn't support Mt Rainier, it can return some data that makes cdrom_is_mrw() incorrectly think the drive is MRW capable.

This problem stops me from mounting DVD+RW discs in R/W mode on my laptop, because it makes cdrom_open_write() call cdrom_mrw_open_write() which fails because the drive isn't really MRW capable.

The fix is to make sure the returned feature number is the correct one for Mt Rainier.

Signed-off-by Peter Osterlund <[email protected]>

---

 linux-petero/drivers/cdrom/cdrom.c |    2 ++
 1 files changed, 2 insertions(+)

diff -puN drivers/cdrom/cdrom.c~mrw-fix drivers/cdrom/cdrom.c

drivers/cdrom/cdrom.c renamed from drivers/cdrom/cdrom.c~mrw-fix +2 -0

@@ -546,6 +546,8 @@ int cdrom_is_mrw(struct cdrom_device_inf
 		return ret;
 
 	mfd = (struct mrw_feature_desc *)&buffer[sizeof(struct feature_header)];
+	if (be16_to_cpu(mfd->feature_code) != CDF_MRW)
+		return 1;
 	*write = mfd->write;
 
 	if ((ret = cdrom_mrw_probe_pc(cdi))) {

_

Signature · 2 lines

Peter Osterlund - [email protected]
http://w1.894.telia.com/~u89404340