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authorDamien Le Moal <damien.lemoal@wdc.com>2017-04-24 16:51:10 +0900
committerMartin K. Petersen <martin.petersen@oracle.com>2017-04-24 19:00:29 -0400
commit6eadc61224666dcc79763dc21749b5f809d82140 (patch)
treeb14107bc46373d10b1727c2b0f348de0b5ad7e50 /drivers/scsi/sd.c
parent7529fbb0080d67bc45a3cdad91574cdd0f8a31cf (diff)
downloadlinux-6eadc61224666dcc79763dc21749b5f809d82140.tar.bz2
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>
Diffstat (limited to 'drivers/scsi/sd.c')
-rw-r--r--drivers/scsi/sd.c51
1 files changed, 27 insertions, 24 deletions
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index c385d903c253..1cc5dd20e2f2 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1758,41 +1758,44 @@ static int sd_eh_action(struct scsi_cmnd *scmd, int eh_disp)
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;
+
/*
- * resid is optional but mostly filled in. When it's unused,
- * its value is zero, so we assume the whole buffer transferred
+ * Some commands have a payload smaller than the device logical
+ * block size (e.g. INQUIRY on a 4K disk).
*/
- unsigned int transferred = scsi_bufflen(scmd) - scsi_get_resid(scmd);
- unsigned int good_bytes;
-
- info_valid = scsi_get_sense_info_fld(scmd->sense_buffer,
- SCSI_SENSE_BUFFERSIZE,
- &bad_lba);
- if (!info_valid)
+ if (scsi_bufflen(scmd) <= sdev->sector_size)
return 0;
- if (scsi_bufflen(scmd) <= scmd->device->sector_size)
+ /* Check if we have a 'bad_lba' information */
+ if (!scsi_get_sense_info_fld(scmd->sense_buffer,
+ SCSI_SENSE_BUFFERSIZE,
+ &bad_lba))
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
+ /*
+ * If the bad lba was reported incorrectly, we have no idea where
* the error is.
*/
- if (bad_lba < start_lba || bad_lba >= end_lba)
+ 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;
- /* This computation should always be done in terms of
- * the resolution of the device's medium.
+ /*
+ * resid is optional but mostly filled in. When it's unused,
+ * its value is zero, so we assume the whole buffer transferred
*/
- good_bytes = (bad_lba - start_lba) * scmd->device->sector_size;
+ transferred = scsi_bufflen(scmd) - scsi_get_resid(scmd);
+
+ /* This computation should always be done in terms of the
+ * resolution of the device's medium.
+ */
+ good_bytes = logical_to_bytes(sdev, bad_lba - start_lba);
+
return min(good_bytes, transferred);
}