From 5616b0a46ed82eb9a093f752fc4d7bd3cc688583 Mon Sep 17 00:00:00 2001
From: "Martin K. Petersen" <martin.petersen@oracle.com>
Date: Tue, 24 Jun 2014 16:59:35 +0200
Subject: [PATCH] [SCSI] use the scsi data buffer length to extract transfer
size
Commit 8846bab180fa introduced a helper that can be used to query the
wire transfer size for a SCSI command taking protection information into
account.
However, some commands do not have a 1:1 mapping between the block range
they work on and the payload size (discard, write same). After the
scatterlist has been set up these requests use __data_len to store the
number of bytes to report completion on. This means that callers of
scsi_transfer_length() would get the wrong byte count for these types of
requests.
To overcome this we make scsi_transfer_length() use the scatterlist
length in the scsi_data_buffer as basis for the wire transfer
calculation instead of __data_len.
Reported-by: Christoph Hellwig <hch@infradead.org>
Debugged-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Fixes: d77e65350f2d82dfa0557707d505711f5a43c8fd
Cc: stable@vger.kernel.org
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
---
include/scsi/scsi_cmnd.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index 42ed789ebafcf9..e0ae71098144ac 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -318,7 +318,7 @@ static inline void set_driver_byte(struct scsi_cmnd *cmd, char status)
static inline unsigned scsi_transfer_length(struct scsi_cmnd *scmd)
{
- unsigned int xfer_len = blk_rq_bytes(scmd->request);
+ unsigned int xfer_len = scsi_out(scmd)->length;
unsigned int prot_op = scsi_get_prot_op(scmd);
unsigned int sector_size = scmd->device->sector_size;
--
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