Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 6eadc612 authored by Damien Le Moal's avatar Damien Le Moal Committed by Martin K. Petersen
Browse files

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: default avatarDamien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 7529fbb0

drivers/scsi/sd.c

+27 −24
Original line number Diff line number Diff line
@@ -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.

	 */

	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);

}

drivers/scsi/sd.h

+5 −0
Original line number Diff line number Diff line
@@ -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);