scsi: sd: Improve sd_completed_bytes
Re-shuffle the code to be more efficient by not initializing variables
upfront (i.e. do it only when necessary). Also replace the do_div calls
with calls to sectors_to_logical().
No functional change is introduced by this patch.
[mkp: bytes_to_logical()]
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index c385d903..1cc5dd2 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1758,41 +1758,44 @@
static unsigned int sd_completed_bytes(struct scsi_cmnd *scmd)
{
- u64 start_lba = blk_rq_pos(scmd->request);
- u64 end_lba = blk_rq_pos(scmd->request) + (scsi_bufflen(scmd) / 512);
- u64 factor = scmd->device->sector_size / 512;
- u64 bad_lba;
- int info_valid;
+ struct request *req = scmd->request;
+ struct scsi_device *sdev = scmd->device;
+ unsigned int transferred, good_bytes;
+ u64 start_lba, end_lba, bad_lba;
+
+ /*
+ * Some commands have a payload smaller than the device logical
+ * block size (e.g. INQUIRY on a 4K disk).
+ */
+ if (scsi_bufflen(scmd) <= sdev->sector_size)
+ return 0;
+
+ /* Check if we have a 'bad_lba' information */
+ if (!scsi_get_sense_info_fld(scmd->sense_buffer,
+ SCSI_SENSE_BUFFERSIZE,
+ &bad_lba))
+ return 0;
+
+ /*
+ * If the bad lba was reported incorrectly, we have no idea where
+ * the error is.
+ */
+ start_lba = sectors_to_logical(sdev, blk_rq_pos(req));
+ end_lba = start_lba + bytes_to_logical(sdev, scsi_bufflen(scmd));
+ if (bad_lba < start_lba || bad_lba >= end_lba)
+ return 0;
+
/*
* resid is optional but mostly filled in. When it's unused,
* its value is zero, so we assume the whole buffer transferred
*/
- unsigned int transferred = scsi_bufflen(scmd) - scsi_get_resid(scmd);
- unsigned int good_bytes;
+ transferred = scsi_bufflen(scmd) - scsi_get_resid(scmd);
- info_valid = scsi_get_sense_info_fld(scmd->sense_buffer,
- SCSI_SENSE_BUFFERSIZE,
- &bad_lba);
- if (!info_valid)
- return 0;
-
- if (scsi_bufflen(scmd) <= scmd->device->sector_size)
- return 0;
-
- /* be careful ... don't want any overflows */
- do_div(start_lba, factor);
- do_div(end_lba, factor);
-
- /* The bad lba was reported incorrectly, we have no idea where
- * the error is.
+ /* This computation should always be done in terms of the
+ * resolution of the device's medium.
*/
- if (bad_lba < start_lba || bad_lba >= end_lba)
- return 0;
+ good_bytes = logical_to_bytes(sdev, bad_lba - start_lba);
- /* This computation should always be done in terms of
- * the resolution of the device's medium.
- */
- good_bytes = (bad_lba - start_lba) * scmd->device->sector_size;
return min(good_bytes, transferred);
}
diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index 0cf9680..e6241c4 100644
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -169,6 +169,11 @@
return blocks * sdev->sector_size;
}
+static inline sector_t bytes_to_logical(struct scsi_device *sdev, unsigned int bytes)
+{
+ return bytes >> ilog2(sdev->sector_size);
+}
+
static inline sector_t sectors_to_logical(struct scsi_device *sdev, sector_t sector)
{
return sector >> (ilog2(sdev->sector_size) - 9);