From: Martin K. Petersen Date: Tue, 18 Sep 2012 16:19:32 +0000 (-0400) Subject: [SCSI] sd: Implement support for WRITE SAME X-Git-Tag: v3.7-rc7~19^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5db44863b6ebbb400c5e61d56ebe8f21ef48b1bd;p=pandora-kernel.git [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 --- Reading git-diff-tree failed