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Commit 0da205e0 authored by Matthew Wilcox's avatar Matthew Wilcox Committed by James Bottomley
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[SCSI] sd: Refactor sd_read_capacity() 



The sd_read_capacity() function was about 180 lines long and
included a backwards goto and a tricky state variable.  Splitting out
read_capacity_10() and read_capacity_16() (about 50 lines each) reduces
sd_read_capacity to about 100 lines and gets rid of the backwards goto
and the state variable.  I've tried to avoid any behaviour change with
this patch.

[jejb: upped transfer request to standard recommended 32 for RC16]
Signed-off-by: default avatarMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
parent 635374e7

drivers/scsi/sd.c

+155 −86
Original line number Diff line number Diff line
@@ -1273,42 +1273,117 @@ disable: 
	sdkp->capacity = 0;

}



static void read_capacity_error(struct scsi_disk *sdkp, struct scsi_device *sdp,

			struct scsi_sense_hdr *sshdr, int sense_valid,

			int the_result)

{

	sd_print_result(sdkp, the_result);

	if (driver_byte(the_result) & DRIVER_SENSE)

		sd_print_sense_hdr(sdkp, sshdr);

	else

		sd_printk(KERN_NOTICE, sdkp, "Sense not available.\n");



	/*

 * read disk capacity

	 * Set dirty bit for removable devices if not ready -

	 * sometimes drives will not report this properly.

	 */

static void

sd_read_capacity(struct scsi_disk *sdkp, unsigned char *buffer)

	if (sdp->removable &&

	    sense_valid && sshdr->sense_key == NOT_READY)

		sdp->changed = 1;



	/*

	 * We used to set media_present to 0 here to indicate no media

	 * in the drive, but some drives fail read capacity even with

	 * media present, so we can't do that.

	 */

	sdkp->capacity = 0; /* unknown mapped to zero - as usual */

}



#define RC16_LEN 32

#if RC16_LEN > SD_BUF_SIZE

#error RC16_LEN must not be more than SD_BUF_SIZE

#endif



static int read_capacity_16(struct scsi_disk *sdkp, struct scsi_device *sdp,

						unsigned char *buffer)

{

	unsigned char cmd[16];

	int the_result, retries;

	int sector_size = 0;

	/* Force READ CAPACITY(16) when PROTECT=1 */

	int longrc = scsi_device_protection(sdkp->device) ? 1 : 0;

	struct scsi_sense_hdr sshdr;

	int sense_valid = 0;

	struct scsi_device *sdp = sdkp->device;

	int the_result;

	int retries = 3;

	unsigned long long lba;

	unsigned sector_size;



repeat:

	retries = 3;

	do {

		if (longrc) {

			memset((void *) cmd, 0, 16);

		memset(cmd, 0, 16);

		cmd[0] = SERVICE_ACTION_IN;

		cmd[1] = SAI_READ_CAPACITY_16;

			cmd[13] = 13;

			memset((void *) buffer, 0, 13);

		} else {

			cmd[0] = READ_CAPACITY;

			memset((void *) &cmd[1], 0, 9);

			memset((void *) buffer, 0, 8);

		cmd[13] = RC16_LEN;

		memset(buffer, 0, RC16_LEN);



		the_result = scsi_execute_req(sdp, cmd, DMA_FROM_DEVICE,

					buffer, RC16_LEN, &sshdr,

					SD_TIMEOUT, SD_MAX_RETRIES, NULL);



		if (media_not_present(sdkp, &sshdr))

			return -ENODEV;



		if (the_result)

			sense_valid = scsi_sense_valid(&sshdr);

		retries--;



	} while (the_result && retries);



	if (the_result) {

		sd_printk(KERN_NOTICE, sdkp, "READ CAPACITY(16) failed\n");

		read_capacity_error(sdkp, sdp, &sshdr, sense_valid, the_result);

		return -EINVAL;

	}



	sector_size =	(buffer[8] << 24) | (buffer[9] << 16) |

			(buffer[10] << 8) | buffer[11];

	lba =  (((u64)buffer[0] << 56) | ((u64)buffer[1] << 48) |

		((u64)buffer[2] << 40) | ((u64)buffer[3] << 32) |

		((u64)buffer[4] << 24) | ((u64)buffer[5] << 16) |

		((u64)buffer[6] << 8) | (u64)buffer[7]);



	sd_read_protection_type(sdkp, buffer);



	if ((sizeof(sdkp->capacity) == 4) && (lba >= 0xffffffffULL)) {

		sd_printk(KERN_ERR, sdkp, "Too big for this kernel. Use a "

			"kernel compiled with support for large block "

			"devices.\n");

		sdkp->capacity = 0;

		return -EOVERFLOW;

	}



	sdkp->capacity = lba + 1;

	return sector_size;

}



static int read_capacity_10(struct scsi_disk *sdkp, struct scsi_device *sdp,

						unsigned char *buffer)

{

	unsigned char cmd[16];

	struct scsi_sense_hdr sshdr;

	int sense_valid = 0;

	int the_result;

	int retries = 3;

	sector_t lba;

	unsigned sector_size;



	do {

		cmd[0] = READ_CAPACITY;

		memset(&cmd[1], 0, 9);

		memset(buffer, 0, 8);



		the_result = scsi_execute_req(sdp, cmd, DMA_FROM_DEVICE,

					      buffer, longrc ? 13 : 8, &sshdr,

					buffer, 8, &sshdr,

					SD_TIMEOUT, SD_MAX_RETRIES, NULL);



		if (media_not_present(sdkp, &sshdr))

			return;

			return -ENODEV;



		if (the_result)

			sense_valid = scsi_sense_valid(&sshdr);
@@ -1316,71 +1391,65 @@ repeat: 


	} while (the_result && retries);



	if (the_result && !longrc) {

	if (the_result) {

		sd_printk(KERN_NOTICE, sdkp, "READ CAPACITY failed\n");

		sd_print_result(sdkp, the_result);

		if (driver_byte(the_result) & DRIVER_SENSE)

			sd_print_sense_hdr(sdkp, &sshdr);

		else

			sd_printk(KERN_NOTICE, sdkp, "Sense not available.\n");



		/* Set dirty bit for removable devices if not ready -

		 * sometimes drives will not report this properly. */

		if (sdp->removable &&

		    sense_valid && sshdr.sense_key == NOT_READY)

			sdp->changed = 1;

		read_capacity_error(sdkp, sdp, &sshdr, sense_valid, the_result);

		return -EINVAL;

	}



		/* Either no media are present but the drive didn't tell us,

		   or they are present but the read capacity command fails */

		/* sdkp->media_present = 0; -- not always correct */

		sdkp->capacity = 0; /* unknown mapped to zero - as usual */

	sector_size =	(buffer[4] << 24) | (buffer[5] << 16) |

			(buffer[6] << 8) | buffer[7];

	lba =	(buffer[0] << 24) | (buffer[1] << 16) |

		(buffer[2] << 8) | buffer[3];



		return;

	} else if (the_result && longrc) {

		/* READ CAPACITY(16) has been failed */

		sd_printk(KERN_NOTICE, sdkp, "READ CAPACITY(16) failed\n");

		sd_print_result(sdkp, the_result);

		sd_printk(KERN_NOTICE, sdkp, "Use 0xffffffff as device size\n");

	if ((sizeof(sdkp->capacity) == 4) && (lba == 0xffffffff)) {

		sd_printk(KERN_ERR, sdkp, "Too big for this kernel. Use a "

			"kernel compiled with support for large block "

			"devices.\n");

		sdkp->capacity = 0;

		return -EOVERFLOW;

	}



		sdkp->capacity = 1 + (sector_t) 0xffffffff;		

		goto got_data;

	sdkp->capacity = lba + 1;

	return sector_size;

}



	if (!longrc) {

		sector_size = (buffer[4] << 24) |

			(buffer[5] << 16) | (buffer[6] << 8) | buffer[7];

		if (buffer[0] == 0xff && buffer[1] == 0xff &&

		    buffer[2] == 0xff && buffer[3] == 0xff) {

			if(sizeof(sdkp->capacity) > 4) {

/*

 * read disk capacity

 */

static void

sd_read_capacity(struct scsi_disk *sdkp, unsigned char *buffer)

{

	int sector_size;

	struct scsi_device *sdp = sdkp->device;



	/* Force READ CAPACITY(16) when PROTECT=1 */

	if (scsi_device_protection(sdp)) {

		sector_size = read_capacity_16(sdkp, sdp, buffer);

		if (sector_size == -EOVERFLOW)

			goto got_data;

		if (sector_size < 0)

			return;

	} else {

		sector_size = read_capacity_10(sdkp, sdp, buffer);

		if (sector_size == -EOVERFLOW)

			goto got_data;

		if (sector_size < 0)

			return;

		if ((sizeof(sdkp->capacity) > 4) &&

		    (sdkp->capacity > 0xffffffffULL)) {

			int old_sector_size = sector_size;

			sd_printk(KERN_NOTICE, sdkp, "Very big device. "

					"Trying to use READ CAPACITY(16).\n");

				longrc = 1;

				goto repeat;

			}

			sd_printk(KERN_ERR, sdkp, "Too big for this kernel. Use "

				  "a kernel compiled with support for large "

				  "block devices.\n");

			sdkp->capacity = 0;

			sector_size = read_capacity_16(sdkp, sdp, buffer);

			if (sector_size < 0) {

				sd_printk(KERN_NOTICE, sdkp,

					"Using 0xffffffff as device size\n");

				sdkp->capacity = 1 + (sector_t) 0xffffffff;

				sector_size = old_sector_size;

				goto got_data;

			}

		sdkp->capacity = 1 + (((sector_t)buffer[0] << 24) |

			(buffer[1] << 16) |

			(buffer[2] << 8) |

			buffer[3]);			

	} else {

		sdkp->capacity = 1 + (((u64)buffer[0] << 56) |

			((u64)buffer[1] << 48) |

			((u64)buffer[2] << 40) |

			((u64)buffer[3] << 32) |

			((sector_t)buffer[4] << 24) |

			((sector_t)buffer[5] << 16) |

			((sector_t)buffer[6] << 8)  |

			(sector_t)buffer[7]);

			

		sector_size = (buffer[8] << 24) |

			(buffer[9] << 16) | (buffer[10] << 8) | buffer[11];



		sd_read_protection_type(sdkp, buffer);

		}

	}



	/* Some devices are known to return the total number of blocks,