On 04/05/2017 07:21 PM, Christoph Hellwig wrote: > From: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx> > > Now that zeroout and discards are distinct operations we need to > separate the policy of choosing the appropriate command. Create a > zeroing_mode which can be one of: > > write: Zeroout assist not present, use regular WRITE > writesame: Allow WRITE SAME(10/16) with a zeroed payload > writesame_16_unmap: Allow WRITE SAME(16) with UNMAP > writesame_10_unmap: Allow WRITE SAME(10) with UNMAP > > The last two are conditional on the device being thin provisioned with > LBPRZ=1 and LBPWS=1 or LBPWS10=1 respectively. > > Whether to set the UNMAP bit or not depends on the REQ_NOUNMAP flag. And > if none of the _unmap variants are supported, regular WRITE SAME will be > used if the device supports it. > > The zeroout_mode is exported in sysfs and the detected mode for a given > device can be overridden using the string constants above. > > With this change in place we can now issue WRITE SAME(16) with UNMAP set > for block zeroing applications that require hard guarantees and > logical_block_size granularity. And at the same time use the UNMAP > command with the device's preferred granulary and alignment for discard > operations. > > Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> > Signed-off-by: Christoph Hellwig <hch@xxxxxx> > --- > drivers/scsi/sd.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++--- > drivers/scsi/sd.h | 8 ++++++++ > 2 files changed, 61 insertions(+), 3 deletions(-) > Reviewed-by: Hannes Reinecke <hare@xxxxxxxx> Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@xxxxxxx +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg) -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
