diff options
| author | Martin K. Petersen <martin.petersen@oracle.com> | 2012-09-18 12:19:32 -0400 |
|---|---|---|
| committer | James Bottomley <JBottomley@Parallels.com> | 2012-11-13 22:45:42 -0800 |
| commit | 5db44863b6ebbb400c5e61d56ebe8f21ef48b1bd (patch) | |
| tree | a352bab202b6cb40f234bd2fd306b54776543e8b /drivers/usb | |
| parent | 26e85fcd15f68b57d9ba645cd3591117a8ac0e05 (diff) | |
[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 'drivers/usb')
| -rw-r--r-- | drivers/usb/storage/scsiglue.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c index 6ab376a7c501..92f35abee92d 100644 --- a/drivers/usb/storage/scsiglue.c +++ b/drivers/usb/storage/scsiglue.c @@ -189,6 +189,9 @@ static int slave_configure(struct scsi_device *sdev) /* Do not attempt to use REPORT SUPPORTED OPERATION CODES */ sdev->no_report_opcodes = 1; + /* Do not attempt to use WRITE SAME */ + sdev->no_write_same = 1; + /* Some disks return the total number of blocks in response * to READ CAPACITY rather than the highest block number. * If this device makes that mistake, tell the sd driver. */ |