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 4b9b7169bdd96957d9a6054ea68ec99c897a2381..1340ffd764844a5a30762c6dc429907e276178f8 100644 (file)
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2777,10 +2777,15 @@ 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(