From 5db44863b6ebbb400c5e61d56ebe8f21ef48b1bd Mon Sep 17 00:00:00 2001 From: "Martin K. Petersen" Date: Tue, 18 Sep 2012 12:19:32 -0400 Subject: [SCSI] sd: Implement support for WRITE SAME Implement support for WRITE SAME(10) and WRITE SAME(16) in the SCSI disk driver. - We set the default maximum to 0xFFFF because there are several devices out there that only support two-byte block counts even with WRITE SAME(16). We only enable transfers bigger than 0xFFFF if the device explicitly reports MAXIMUM WRITE SAME LENGTH in the BLOCK LIMITS VPD. - max_write_same_blocks can be overriden per-device basis in sysfs. - The UNMAP discovery heuristics remain unchanged but the discard limits are tweaked to match the "real" WRITE SAME commands. - In the error handling logic we now distinguish between WRITE SAME with and without UNMAP set. The discovery process heuristics are: - If the device reports a SCSI level of SPC-3 or greater we'll issue READ SUPPORTED OPERATION CODES to find out whether WRITE SAME(16) is supported. If that's the case we will use it. - If the device supports the block limits VPD and reports a MAXIMUM WRITE SAME LENGTH bigger than 0xFFFF we will use WRITE SAME(16). - Otherwise we will use WRITE SAME(10) unless the target LBA is beyond 0xFFFFFFFF or the block count exceeds 0xFFFF. - no_write_same is set for ATA, FireWire and USB. Signed-off-by: Martin K. Petersen Reviewed-by: Mike Snitzer Reviewed-by: Jeff Garzik Signed-off-by: James Bottomley --- include/scsi/scsi_device.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/scsi') diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index 379d465e8070..55367b04dc94 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -136,6 +136,7 @@ struct scsi_device { 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 no_report_opcodes:1; /* no REPORT SUPPORTED OPERATION CODES */ + unsigned no_write_same:1; /* no WRITE SAME command */ 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 skip_vpd_pages:1; /* do not read VPD pages */ -- cgit v1.2.3-59-g8ed1b