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| author | Martin K. Petersen <martin.petersen@oracle.com> | 2012-09-18 18:19:32 +0200 |
|---|---|---|
| committer | James Bottomley <JBottomley@Parallels.com> | 2012-11-14 07:45:42 +0100 |
| commit | 5db44863b6ebbb400c5e61d56ebe8f21ef48b1bd (patch) | |
| tree | a352bab202b6cb40f234bd2fd306b54776543e8b /include/scsi/scsi_device.h | |
| parent | [SCSI] sd: Permit merged discard requests (diff) | |
| download | linux-5db44863b6ebbb400c5e61d56ebe8f21ef48b1bd.tar.xz linux-5db44863b6ebbb400c5e61d56ebe8f21ef48b1bd.zip | |
[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 <martin.petersen@oracle.com>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Diffstat (limited to 'include/scsi/scsi_device.h')
| -rw-r--r-- | include/scsi/scsi_device.h | 1 |
1 files changed, 1 insertions, 0 deletions
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 */ |