From: Martin K. Petersen <martin.petersen@oracle.com>

Add support for data integrity to DM.

If all subdevices support the same protection format the DM device is
flagged as capable.

[FIXME: Doesn't yet cope with integrity profile needing removing after
a table swap.  blk_integrity_register() allocating & manipulating kobjects
needs moving outside __bind().]

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

---
 drivers/md/dm-table.c |   38 ++++++++++++++++++++++++++++++++++++++
 drivers/md/dm.c       |   15 +++++++++++++++
 2 files changed, 53 insertions(+)

Index: linux-2.6.28-devel/drivers/md/dm-table.c
===================================================================
--- linux-2.6.28-devel.orig/drivers/md/dm-table.c	2009-01-07 02:32:49.000000000 +0100
+++ linux-2.6.28-devel/drivers/md/dm-table.c	2009-01-07 02:32:56.000000000 +0100
@@ -864,6 +864,43 @@ struct dm_target *dm_table_find_target(s
 	return &t->targets[(KEYS_PER_NODE * n) + k];
 }
 
+/*
+ * Set the integrity profile for this device if all devices used have
+ * matching profiles.
+ */
+static void dm_table_set_integrity(struct dm_table *t)
+{
+	struct list_head *devices = dm_table_get_devices(t);
+	struct dm_dev_internal *prev = NULL, *dd = NULL;
+	struct blk_integrity *bi;
+
+	list_for_each_entry(dd, devices, list) {
+		if (prev &&
+		    blk_integrity_compare(prev->dm_dev.bdev->bd_disk,
+					  dd->dm_dev.bdev->bd_disk) < 0) {
+			DMWARN("%s: integrity not set: %s and %s mismatch",
+			       dm_device_name(t->md),
+			       prev->dm_dev.bdev->bd_disk->disk_name,
+			       dd->dm_dev.bdev->bd_disk->disk_name);
+			return;
+		}
+		prev = dd;
+	}
+
+	if (!prev)
+		return;
+
+	bi = bdev_get_integrity(prev->dm_dev.bdev);
+	if (!bi)
+		return;
+
+	if (blk_integrity_register(dm_disk(t->md), bi))
+		DMERR("%s: %s: blk_integrity_register failed.",
+		       __func__, dm_device_name(t->md));
+	else
+		DMDEBUG("%s: Enabling data integrity.", dm_device_name(t->md));
+}
+
 void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q)
 {
 	/*
@@ -884,6 +921,7 @@ void dm_table_set_restrictions(struct dm
 	else
 		queue_flag_set_unlocked(QUEUE_FLAG_CLUSTER, q);
 
+	dm_table_set_integrity(t);
 }
 
 unsigned int dm_table_get_num_targets(struct dm_table *t)
Index: linux-2.6.28-devel/drivers/md/dm.c
===================================================================
--- linux-2.6.28-devel.orig/drivers/md/dm.c	2009-01-07 02:32:49.000000000 +0100
+++ linux-2.6.28-devel/drivers/md/dm.c	2009-01-07 02:32:56.000000000 +0100
@@ -698,6 +698,12 @@ static struct bio *split_bvec(struct bio
 	clone->bi_io_vec->bv_len = clone->bi_size;
 	clone->bi_flags |= 1 << BIO_CLONED;
 
+	if (bio_integrity(bio)) {
+		bio_integrity_clone(clone, bio, bs);
+		bio_integrity_trim(clone,
+				   bio_sector_offset(bio, idx, offset), len);
+	}
+
 	return clone;
 }
 
@@ -719,6 +725,14 @@ static struct bio *clone_bio(struct bio 
 	clone->bi_size = to_bytes(len);
 	clone->bi_flags &= ~(1 << BIO_SEG_VALID);
 
+	if (bio_integrity(bio)) {
+		bio_integrity_clone(clone, bio, bs);
+
+		if (idx != bio->bi_idx || clone->bi_size < bio->bi_size)
+			bio_integrity_trim(clone,
+					   bio_sector_offset(bio, idx, 0), len);
+	}
+
 	return clone;
 }
 
@@ -1191,6 +1205,7 @@ static void free_dev(struct mapped_devic
 	mempool_destroy(md->tio_pool);
 	mempool_destroy(md->io_pool);
 	bioset_free(md->bs);
+	blk_integrity_unregister(md->disk);
 	del_gendisk(md->disk);
 	free_minor(minor);