I recommend broadening this patch. T10 is discussing making READ (10), WRITE (10), etc. obsolete in SBC-4 in favor of their 16-byte CDB counterparts. The algorithm should be: 1. During discovery, determine if 16-byte CDBs are supported. There are several ways to determine this: a) REPORT SUPPORTED OPERATION CODES command succeeds and reports that READ (16) et al are supported. b) READ (16) command specifying a Transfer Length of zero succeeds. c) READ CAPACITY (16) command succeeds and reports that the capacity is > 2 TiB. d) (future) INQUIRY command succeeds fetching the Block Device Characteristics VPD page and notices a new field added by the SBC-4 simplified SCSI feature set proposal. Since REPORT SUPPORTED OPERATION CODES is optional, it won't always work. READ CAPACITY (16) used to be optional for < 2 TiB drives, so it won't always work either. READ (16) will always work, but requires the drive to be spun up beforehand (e.g., with START STOP UNIT). 2. if 16-byte CDBs are supported, then use them; only drop down to 10-byte CDBs if 16-byte CDBs are unavailable. Don't make the decision by comparing the LBA on every IO. -----Original Message----- From: linux-scsi-owner@xxxxxxxxxxxxxxx [mailto:linux-scsi-owner@xxxxxxxxxxxxxxx] On Behalf Of Jason J. Herne Sent: Friday, November 09, 2012 9:08 AM To: linux-scsi@xxxxxxxxxxxxxxx Cc: linux-usb@xxxxxxxxxxxxxxx; stern@xxxxxxxxxxxxxxxxxxx; Jason J. Herne Subject: [PATCH] USB enclosures seem to require read(16) with >2TB drives From: "Jason J. Herne" <hernejj@xxxxxxxxx> Force large capacity (> 2TB) drives in USB enclosures to use READ(16) instead of READ(10). Some(most/all?) enclosures do not like READ(10) commands when a large capacity drive is installed. Signed-off-by: Jason J. Herne <hernejj@xxxxxxxxx> --- drivers/scsi/sd.c | 7 +++++-- drivers/usb/storage/scsiglue.c | 5 +++++ include/scsi/scsi_device.h | 1 + 3 files changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 4b63c73..9b65ddf 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -649,7 +649,7 @@ static int sd_prep_fn(struct request_queue *q, struct request *rq) sector_t block = blk_rq_pos(rq); sector_t threshold; unsigned int this_count = blk_rq_sectors(rq); - int ret, host_dif; + int ret, host_dif, force_read16; unsigned char protect; /* @@ -797,6 +797,9 @@ static int sd_prep_fn(struct request_queue *q, struct request *rq) else protect = 0; + /* Many large capacity USB drives/controllers require the use of read(16). */ + force_read16 = (sdkp->capacity > 0xffffffffULL && sdp->force_read_16); + if (host_dif == SD_DIF_TYPE2_PROTECTION) { SCpnt->cmnd = mempool_alloc(sd_cdb_pool, GFP_ATOMIC); @@ -833,7 +836,7 @@ static int sd_prep_fn(struct request_queue *q, struct request *rq) SCpnt->cmnd[29] = (unsigned char) (this_count >> 16) & 0xff; SCpnt->cmnd[30] = (unsigned char) (this_count >> 8) & 0xff; SCpnt->cmnd[31] = (unsigned char) this_count & 0xff; - } else if (block > 0xffffffff) { + } else if (block > 0xffffffff || force_read16) { SCpnt->cmnd[0] += READ_16 - READ_6; SCpnt->cmnd[1] = protect | ((rq->cmd_flags & REQ_FUA) ? 0x8 : 0); SCpnt->cmnd[2] = sizeof(block) > 4 ? (unsigned char) (block >> 56) & 0xff : 0; diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c index 13b8bcd..6ff785e 100644 --- a/drivers/usb/storage/scsiglue.c +++ b/drivers/usb/storage/scsiglue.c @@ -251,6 +251,11 @@ static int slave_configure(struct scsi_device *sdev) US_FL_SCM_MULT_TARG)) && us->protocol == USB_PR_BULK) us->use_last_sector_hacks = 1; + + /* Force read-16 for large capacity drives. */ + sdev->force_read_16 = 1; + + } else { /* Non-disk-type devices don't need to blacklist any pages diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index 5591ed5..e92b846 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -134,6 +134,7 @@ struct scsi_device { * because we did a bus reset. */ unsigned use_10_for_rw:1; /* first try 10-byte read / write */ unsigned use_10_for_ms:1; /* first try 10-byte mode sense/select */ + unsigned force_read_16:1; /* Use read(16) over read(10) */ unsigned skip_ms_page_8:1; /* do not use MODE SENSE page 0x08 */ unsigned skip_ms_page_3f:1; /* do not use MODE SENSE page 0x3f */ unsigned use_192_bytes_for_3f:1; /* ask for 192 bytes from page 0x3f */ -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
