Send WRITE SAME request with the unmap bit set to the device if it
advertises thin provisioning support. Still pretty hacky and not
actually looking at the INQUIRY data for the unmap parameters for
example.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Index: linux-2.6/drivers/scsi/sd.c
===================================================================
--- linux-2.6.orig/drivers/scsi/sd.c 2009-09-17 13:12:00.743253792 -0300
+++ linux-2.6/drivers/scsi/sd.c 2009-09-17 13:18:31.185005932 -0300
@@ -370,6 +370,35 @@ static void scsi_disk_put(struct scsi_di
mutex_unlock(&sd_ref_mutex);
}
+static void sd_prepare_discard(struct request_queue *q, struct request *rq)
+{
+ struct bio *bio = rq->bio;
+
+ rq->cmd_type = REQ_TYPE_BLOCK_PC;
+ rq->timeout = SD_TIMEOUT;
+ rq->cmd[0] = WRITE_SAME_16;
+ rq->cmd[1] = 0x8; /* UNMAP bit */
+ rq->cmd[2] = sizeof(bio->bi_sector) > 4 ?
+ (unsigned char) (bio->bi_sector >> 56) & 0xff : 0;
+ rq->cmd[3] = sizeof(bio->bi_sector) > 4 ?
+ (unsigned char) (bio->bi_sector >> 48) & 0xff : 0;
+ rq->cmd[4] = sizeof(bio->bi_sector) > 4 ?
+ (unsigned char) (bio->bi_sector >> 40) & 0xff : 0;
+ rq->cmd[5] = sizeof(bio->bi_sector) > 4 ?
+ (unsigned char) (bio->bi_sector >> 32) & 0xff : 0;
+ rq->cmd[6] = (unsigned char) (bio->bi_sector >> 24) & 0xff;
+ rq->cmd[7] = (unsigned char) (bio->bi_sector >> 16) & 0xff;
+ rq->cmd[8] = (unsigned char) (bio->bi_sector >> 8) & 0xff;
+ rq->cmd[9] = (unsigned char) bio->bi_sector & 0xff;
+ rq->cmd[10] = (unsigned char) (bio_sectors(bio) >> 24) & 0xff;
+ rq->cmd[11] = (unsigned char) (bio_sectors(bio) >> 16) & 0xff;
+ rq->cmd[12] = (unsigned char) (bio_sectors(bio) >> 8) & 0xff;
+ rq->cmd[13] = (unsigned char) bio_sectors(bio) & 0xff;
+ rq->cmd[14] = 0;
+ rq->cmd[15] = 0;
+ rq->cmd_len = 16;
+}
+
/**
* sd_init_command - build a scsi (read or write) command from
* information in the request structure.
@@ -389,6 +418,13 @@ static int sd_prep_fn(struct request_que
unsigned int this_count = blk_rq_sectors(rq);
int ret, host_dif;
+ /*
+ * Discard request come in as REQ_TYPE_FS but we turn them into
+ * block PC requests to make life easier.
+ */
+ if (blk_discard_rq(rq))
+ sd_prepare_discard(q, rq);
+
if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
ret = scsi_setup_blk_pc_cmnd(sdp, rq);
goto out;
@@ -396,6 +432,7 @@ static int sd_prep_fn(struct request_que
ret = BLKPREP_KILL;
goto out;
}
+
ret = scsi_setup_fs_cmnd(sdp, rq);
if (ret != BLKPREP_OK)
goto out;
@@ -1369,6 +1406,9 @@ static int read_capacity_16(struct scsi_
sd_printk(KERN_NOTICE, sdkp,
"physical block alignment offset: %u\n", alignment);
+ if (buffer[14] & 0x80)
+ sdkp->thin_provisioning = 1;
+
sdkp->capacity = lba + 1;
return sector_size;
}
@@ -1916,6 +1956,11 @@ static int sd_revalidate_disk(struct gen
blk_queue_ordered(sdkp->disk->queue, ordered, sd_prepare_flush);
+ if (sdkp->thin_provisioning) {
+ queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, sdkp->disk->queue);
+ blk_queue_max_discard_sectors(sdp->request_queue, UINT_MAX);
+ }
+
set_capacity(disk, sdkp->capacity);
kfree(buffer);
Index: linux-2.6/include/scsi/scsi.h
===================================================================
--- linux-2.6.orig/include/scsi/scsi.h 2009-09-17 13:12:00.756253702 -0300
+++ linux-2.6/include/scsi/scsi.h 2009-09-17 13:12:21.031004671 -0300
@@ -122,6 +122,8 @@ struct scsi_cmnd;
#define READ_16 0x88
#define WRITE_16 0x8a
#define VERIFY_16 0x8f
+#define WRITE_SAME_16 0x93
+
#define SERVICE_ACTION_IN 0x9e
/* values for service action in */
#define SAI_READ_CAPACITY_16 0x10
Index: linux-2.6/drivers/scsi/sd.h
===================================================================
--- linux-2.6.orig/drivers/scsi/sd.h 2009-09-17 13:12:00.750254405 -0300
+++ linux-2.6/drivers/scsi/sd.h 2009-09-17 13:12:21.034025726 -0300
@@ -55,6 +55,7 @@ struct scsi_disk {
unsigned RCD : 1; /* state of disk RCD bit, unused */
unsigned DPOFUA : 1; /* state of disk DPOFUA bit */
unsigned first_scan : 1;
+ unsigned thin_provisioning : 1;
};
#define to_scsi_disk(obj) container_of(obj,struct scsi_disk,dev)
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