Commit 03aba2f7 authored by Luben Tuikov's avatar Luben Tuikov Committed by James Bottomley
Browse files

[SCSI] sd/scsi_lib simplify sd_rw_intr and scsi_io_completion 



This patch simplifies "good_bytes" computation in sd_rw_intr().
sd: "good_bytes" computation is always done in terms of the resolution
of the device's medium, since after that it is the number of good bytes
we pass around and other layers/contexts (as opposed ot sd) can translate
that to their own resolution (block layer:512).  It also makes
scsi_io_completion() processing more straightforward, eliminating the
3rd argument to the function.

It also fixes a couple of bugs like not checking return value,
using "break" instead of "return;", etc.

I've been running with this patch for some time now on a
test (do-it-all) system.

Signed-off-by: default avatarLuben Tuikov <ltuikov@yahoo.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@SteelEye.com>
parent f89d0a4e

drivers/scsi/scsi_lib.c

+42 −66
Original line number Diff line number Diff line
@@ -855,8 +855,7 @@ static void scsi_release_buffers(struct scsi_cmnd *cmd) 
 *		b) We can just use scsi_requeue_command() here.  This would

 *		   be used if we just wanted to retry, for example.

 */

void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes,

			unsigned int block_bytes)

void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)

{

	int result = cmd->result;

	int this_count = cmd->bufflen;
@@ -921,51 +920,38 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes, 
	 * Next deal with any sectors which we were able to correctly

	 * handle.

	 */

	if (good_bytes >= 0) {

		SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, %d bytes done.\n",

	if (good_bytes > 0) {

		SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, "

					      "%d bytes done.\n",

					      req->nr_sectors, good_bytes));

		SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg));



		if (clear_errors)

			req->errors = 0;

		/*

		 * If multiple sectors are requested in one buffer, then

		 * they will have been finished off by the first command.

		 * If not, then we have a multi-buffer command.

		 *

		 * If block_bytes != 0, it means we had a medium error

		 * of some sort, and that we want to mark some number of

		 * sectors as not uptodate.  Thus we want to inhibit

		 * requeueing right here - we will requeue down below

		 * when we handle the bad sectors.

		 */



		/*

		 * If the command completed without error, then either

		 * finish off the rest of the command, or start a new one.

		/* A number of bytes were successfully read.  If there

		 * is leftovers and there is some kind of error

		 * (result != 0), retry the rest.

		 */

		if (scsi_end_request(cmd, 1, good_bytes, result == 0) == NULL)

		if (scsi_end_request(cmd, 1, good_bytes, !!result) == NULL)

			return;

	}

	/*

	 * Now, if we were good little boys and girls, Santa left us a request

	 * sense buffer.  We can extract information from this, so we

	 * can choose a block to remap, etc.



	/* good_bytes = 0, or (inclusive) there were leftovers and

	 * result = 0, so scsi_end_request couldn't retry.

	 */

	if (sense_valid && !sense_deferred) {

		switch (sshdr.sense_key) {

		case UNIT_ATTENTION:

			if (cmd->device->removable) {

				/* detected disc change.  set a bit 

				/* Detected disc change.  Set a bit

				 * and quietly refuse further access.

				 */

				cmd->device->changed = 1;

				scsi_end_request(cmd, 0,

						this_count, 1);

				scsi_end_request(cmd, 0, this_count, 1);

				return;

			} else {

				/*

				* Must have been a power glitch, or a

				/* Must have been a power glitch, or a

				 * bus reset.  Could not have been a

				 * media change, so we just retry the

				 * request and see what happens.
@@ -975,33 +961,31 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes, 
			}

			break;

		case ILLEGAL_REQUEST:

			/*

		 	* If we had an ILLEGAL REQUEST returned, then we may

		 	* have performed an unsupported command.  The only

		 	* thing this should be would be a ten byte read where

			* only a six byte read was supported.  Also, on a

			* system where READ CAPACITY failed, we may have read

			* past the end of the disk.

			/* If we had an ILLEGAL REQUEST returned, then

			 * we may have performed an unsupported

			 * command.  The only thing this should be

			 * would be a ten byte read where only a six

			 * byte read was supported.  Also, on a system

			 * where READ CAPACITY failed, we may have

			 * read past the end of the disk.

			 */

			if ((cmd->device->use_10_for_rw &&

			    sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&

			    (cmd->cmnd[0] == READ_10 ||

			     cmd->cmnd[0] == WRITE_10)) {

				cmd->device->use_10_for_rw = 0;

				/*

				 * This will cause a retry with a 6-byte

				 * command.

				/* This will cause a retry with a

				 * 6-byte command.

				 */

				scsi_requeue_command(q, cmd);

				result = 0;

				return;

			} else {

				scsi_end_request(cmd, 0, this_count, 1);

				return;

			}

			break;

		case NOT_READY:

			/*

			 * If the device is in the process of becoming

			/* If the device is in the process of becoming

			 * ready, or has a temporary blockage, retry.

			 */

			if (sshdr.asc == 0x04) {
@@ -1033,17 +1017,17 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes, 
				__scsi_print_command(cmd->data_cmnd);

				scsi_print_sense("", cmd);

			}

			scsi_end_request(cmd, 0, block_bytes, 1);

			/* See SSC3rXX or current. */

			scsi_end_request(cmd, 0, this_count, 1);

			return;

		default:

			break;

		}

	}			/* driver byte != 0 */

	}

	if (host_byte(result) == DID_RESET) {

		/*

		 * Third party bus reset or reset for error

		 * recovery reasons.  Just retry the request

		 * and see what happens.  

		/* Third party bus reset or reset for error recovery

		 * reasons.  Just retry the request and see what

		 * happens.

		 */

		scsi_requeue_command(q, cmd);

		return;
@@ -1051,21 +1035,13 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes, 
	if (result) {

		if (!(req->flags & REQ_QUIET)) {

			scmd_printk(KERN_INFO, cmd,

				   "SCSI error: return code = 0x%x\n", result);



				    "SCSI error: return code = 0x%08x\n",

				    result);

			if (driver_byte(result) & DRIVER_SENSE)

				scsi_print_sense("", cmd);

		}

		/*

		 * Mark a single buffer as not uptodate.  Queue the remainder.

		 * We sometimes get this cruft in the event that a medium error

		 * isn't properly reported.

		 */

		block_bytes = req->hard_cur_sectors << 9;

		if (!block_bytes)

			block_bytes = req->data_len;

		scsi_end_request(cmd, 0, block_bytes, 1);

	}

	scsi_end_request(cmd, 0, this_count, !result);

}

EXPORT_SYMBOL(scsi_io_completion);
@@ -1169,7 +1145,7 @@ static void scsi_blk_pc_done(struct scsi_cmnd *cmd) 
	 * successfully. Since this is a REQ_BLOCK_PC command the

	 * caller should check the request's errors value

	 */

	scsi_io_completion(cmd, cmd->bufflen, 0);

	scsi_io_completion(cmd, cmd->bufflen);

}



static void scsi_setup_blk_pc_cmnd(struct scsi_cmnd *cmd)

drivers/scsi/sd.c

+62 −81
Original line number Diff line number Diff line
@@ -891,11 +891,10 @@ static struct block_device_operations sd_fops = { 
static void sd_rw_intr(struct scsi_cmnd * SCpnt)

{

	int result = SCpnt->result;

	int this_count = SCpnt->request_bufflen;

	int good_bytes = (result == 0 ? this_count : 0);

	sector_t block_sectors = 1;

	u64 first_err_block;

	sector_t error_sector;

 	unsigned int xfer_size = SCpnt->request_bufflen;

 	unsigned int good_bytes = result ? 0 : xfer_size;

 	u64 start_lba = SCpnt->request->sector;

 	u64 bad_lba;

	struct scsi_sense_hdr sshdr;

	int sense_valid = 0;

	int sense_deferred = 0;
@@ -906,7 +905,6 @@ static void sd_rw_intr(struct scsi_cmnd * SCpnt) 
		if (sense_valid)

			sense_deferred = scsi_sense_is_deferred(&sshdr);

	}



#ifdef CONFIG_SCSI_LOGGING

	SCSI_LOG_HLCOMPLETE(1, printk("sd_rw_intr: %s: res=0x%x\n", 

				SCpnt->request->rq_disk->disk_name, result));
@@ -916,68 +914,57 @@ static void sd_rw_intr(struct scsi_cmnd * SCpnt) 
				sshdr.sense_key, sshdr.asc, sshdr.ascq));

	}

#endif

	/*

	   Handle MEDIUM ERRORs that indicate partial success.  Since this is a

	   relatively rare error condition, no care is taken to avoid

	   unnecessary additional work such as memcpy's that could be avoided.

	 */

	if (driver_byte(result) != 0 &&

		 sense_valid && !sense_deferred) {

	if (driver_byte(result) != DRIVER_SENSE &&

	    (!sense_valid || sense_deferred))

		goto out;



	switch (sshdr.sense_key) {

	case HARDWARE_ERROR:

	case MEDIUM_ERROR:

		if (!blk_fs_request(SCpnt->request))

				break;

			info_valid = scsi_get_sense_info_fld(

				SCpnt->sense_buffer, SCSI_SENSE_BUFFERSIZE,

				&first_err_block);

			/*

			 * May want to warn and skip if following cast results

			 * in actual truncation (if sector_t < 64 bits)

			 */

			error_sector = (sector_t)first_err_block;

			if (SCpnt->request->bio != NULL)

				block_sectors = bio_sectors(SCpnt->request->bio);

			goto out;

		info_valid = scsi_get_sense_info_fld(SCpnt->sense_buffer,

						     SCSI_SENSE_BUFFERSIZE,

						     &bad_lba);

		if (!info_valid)

			goto out;

		if (xfer_size <= SCpnt->device->sector_size)

			goto out;

		switch (SCpnt->device->sector_size) {

		case 256:

			start_lba <<= 1;

			break;

		case 512:

			break;

		case 1024:

				error_sector <<= 1;

				if (block_sectors < 2)

					block_sectors = 2;

			start_lba >>= 1;

			break;

		case 2048:

				error_sector <<= 2;

				if (block_sectors < 4)

					block_sectors = 4;

			start_lba >>= 2;

			break;

		case 4096:

				error_sector <<=3;

				if (block_sectors < 8)

					block_sectors = 8;

				break;

			case 256:

				error_sector >>= 1;

			start_lba >>= 3;

			break;

		default:

			/* Print something here with limiting frequency. */

			goto out;

			break;

		}



			error_sector &= ~(block_sectors - 1);

			good_bytes = (error_sector - SCpnt->request->sector) << 9;

			if (good_bytes < 0 || good_bytes >= this_count)

				good_bytes = 0;

		/* This computation should always be done in terms of

		 * the resolution of the device's medium.

		 */

		good_bytes = (bad_lba - start_lba)*SCpnt->device->sector_size;

		break;



		case RECOVERED_ERROR: /* an error occurred, but it recovered */

		case NO_SENSE: /* LLDD got sense data */

			/*

			 * Inform the user, but make sure that it's not treated

	case RECOVERED_ERROR:

	case NO_SENSE:

		/* Inform the user, but make sure that it's not treated

		 * as a hard error.

		 */

		scsi_print_sense("sd", SCpnt);

		SCpnt->result = 0;

		memset(SCpnt->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);

			good_bytes = this_count;

		good_bytes = xfer_size;

		break;



	case ILLEGAL_REQUEST:

		if (SCpnt->device->use_10_for_rw &&

		    (SCpnt->cmnd[0] == READ_10 ||
@@ -988,17 +975,11 @@ static void sd_rw_intr(struct scsi_cmnd * SCpnt) 
		     SCpnt->cmnd[0] == MODE_SELECT_10))

			SCpnt->device->use_10_for_ms = 0;

		break;



	default:

		break;

	}

	}

	/*

	 * This calls the generic completion function, now that we know

	 * how many actual sectors finished, and how many sectors we need

	 * to say have failed.

	 */

	scsi_io_completion(SCpnt, good_bytes, block_sectors << 9);

 out:

	scsi_io_completion(SCpnt, good_bytes);

}



static int media_not_present(struct scsi_disk *sdkp,

drivers/scsi/sr.c

+1 −1
Original line number Diff line number Diff line
@@ -292,7 +292,7 @@ static void rw_intr(struct scsi_cmnd * SCpnt) 
	 * how many actual sectors finished, and how many sectors we need

	 * to say have failed.

	 */

	scsi_io_completion(SCpnt, good_bytes, block_sectors << 9);

	scsi_io_completion(SCpnt, good_bytes);

}



static int sr_init_command(struct scsi_cmnd * SCpnt)

include/scsi/scsi_cmnd.h

+1 −1
Original line number Diff line number Diff line
@@ -143,7 +143,7 @@ struct scsi_cmnd { 


extern struct scsi_cmnd *scsi_get_command(struct scsi_device *, gfp_t);

extern void scsi_put_command(struct scsi_cmnd *);

extern void scsi_io_completion(struct scsi_cmnd *, unsigned int, unsigned int);

extern void scsi_io_completion(struct scsi_cmnd *, unsigned int);

extern void scsi_finish_command(struct scsi_cmnd *cmd);

extern void scsi_req_abort_cmd(struct scsi_cmnd *cmd);

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