target: Handle 0 correctly in transport_get_sectors_6()

commit 9b5cd7f37e1e018432111333e2a67f78ba41edfe upstream.

SBC-3 says:

    A TRANSFER LENGTH field set to zero specifies that 256 logical
    blocks shall be written.  Any other value specifies the number
    of logical blocks that shall be written.

The old code was always just returning the value in the TRANSFER LENGTH
byte.  Fix this to return 256 if the byte is 0.

Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 42d9074f7ea42c6ad3be6f40a502f1ebdbd130e8..e2added477b96e41528243078f28cbd4dfd6b889 100644 (file)
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2562,10 +2562,15 @@ static inline u32 transport_get_sectors_6(
 
        /*
         * Everything else assume TYPE_DISK Sector CDB location.
-        * Use 8-bit sector value.
+        * Use 8-bit sector value.  SBC-3 says:
+        *
+        *   A TRANSFER LENGTH field set to zero specifies that 256
+        *   logical blocks shall be written.  Any other value
+        *   specifies the number of logical blocks that shall be
+        *   written.
         */
 type_disk:
-       return (u32)cdb[4];
+       return cdb[4] ? : 256;
 }
 
 static inline u32 transport_get_sectors_10(