From 6eadc61224666dcc79763dc21749b5f809d82140 Mon Sep 17 00:00:00 2001 From: Damien Le Moal Date: Mon, 24 Apr 2017 16:51:10 +0900 Subject: [PATCH] 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 Reviewed-by: Christoph Hellwig Signed-off-by: Martin K. Petersen --- drivers/scsi/sd.c | 51 +++++++++++++++++++++++++---------------------- drivers/scsi/sd.h | 5 +++++ 2 files changed, 32 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); } diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h index 0cf9680cb469..e6241c445878 100644 --- a/drivers/scsi/sd.h +++ b/drivers/scsi/sd.h @@ -169,6 +169,11 @@ static inline unsigned int logical_to_bytes(struct scsi_device *sdev, sector_t b 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); -- 2.20.1