dm: mark targets that pass integrity data

A dm-crypt on dm-integrity device incorrectly advertises an integrity
profile on the DM crypt device.  It can be seen in the files
"/sys/block/dm-*/integrity/*" that both dm-integrity and dm-crypt target
advertise the integrity profile.  That is incorrect, only the
dm-integrity target should advertise the integrity profile.

A general problem in DM is that if we have a DM device that depends on
another device with an integrity profile, the upper device will always
advertise the integrity profile, even when the target driver doesn't
support handling integrity data.

Most targets don't support integrity data, so we provide a whitelist of
targets that support it (linear, delay and striped).  The targets that
support passing integrity data to the lower device are marked with the
flag DM_TARGET_PASSES_INTEGRITY.  The DM core will now advertise
integrity data on a DM device only if all the targets support the
integrity data.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

6 files changed, 29 insertions, 3 deletions

diff --git a/drivers/md/dm-delay.c b/drivers/md/dm-delay.c
index cc70871a6d29..ae3158795d26 100644
--- a/drivers/md/dm-delay.c
+++ b/drivers/md/dm-delay.c
@@ -340,6 +340,7 @@ out:
 static struct target_type delay_target = {
 	.name	     = "delay",
 	.version     = {1, 2, 1},
+	.features    = DM_TARGET_PASSES_INTEGRITY,
 	.module      = THIS_MODULE,
 	.ctr	     = delay_ctr,
 	.dtr	     = delay_dtr,
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 4788b0b989a9..ffa0c9c5968a 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -162,6 +162,7 @@ static long linear_direct_access(struct dm_target *ti, sector_t sector,
 static struct target_type linear_target = {
 	.name   = "linear",
 	.version = {1, 3, 0},
+	.features = DM_TARGET_PASSES_INTEGRITY,
 	.module = THIS_MODULE,
 	.ctr    = linear_ctr,
 	.dtr    = linear_dtr,
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index 28193a57bf47..d7e1b86e7570 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -440,6 +440,7 @@ static void stripe_io_hints(struct dm_target *ti,
 static struct target_type stripe_target = {
 	.name   = "striped",
 	.version = {1, 6, 0},
+	.features = DM_TARGET_PASSES_INTEGRITY,
 	.module = THIS_MODULE,
 	.ctr    = stripe_ctr,
 	.dtr    = stripe_dtr,
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 7fb29db478cd..c68757f94e16 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1135,6 +1135,13 @@ static struct gendisk * dm_table_get_integrity_disk(struct dm_table *t)
 	struct list_head *devices = dm_table_get_devices(t);
 	struct dm_dev_internal *dd = NULL;
 	struct gendisk *prev_disk = NULL, *template_disk = NULL;
+	unsigned i;
+
+	for (i = 0; i < dm_table_get_num_targets(t); i++) {
+		struct dm_target *ti = dm_table_get_target(t, i);
+		if (!dm_target_passes_integrity(ti->type))
+			goto no_integrity;
+	}
 
 	list_for_each_entry(dd, devices, list) {
 		template_disk = dd->dm_dev->bdev->bd_disk;
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index f4ffd1eb8f44..e602ae0d5d75 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1089,8 +1089,18 @@ static int clone_bio(struct dm_target_io *tio, struct bio *bio,
 
 	__bio_clone_fast(clone, bio);
 
-	if (bio_integrity(bio)) {
-		int r = bio_integrity_clone(clone, bio, GFP_NOIO);
+	if (unlikely(bio_integrity(bio) != NULL)) {
+		int r;
+
+		if (unlikely(!dm_target_has_integrity(tio->ti->type) &&
+			     !dm_target_passes_integrity(tio->ti->type))) {
+			DMWARN("%s: the target %s doesn't support integrity data.",
+				dm_device_name(tio->io->md),
+				tio->ti->type->name);
+			return -EIO;
+		}
+
+		r = bio_integrity_clone(clone, bio, GFP_NOIO);
 		if (r < 0)
 			return r;
 	}
@@ -1098,7 +1108,7 @@ static int clone_bio(struct dm_target_io *tio, struct bio *bio,
 	bio_advance(clone, to_bytes(sector - clone->bi_iter.bi_sector));
 	clone->bi_iter.bi_size = to_bytes(len);
 
-	if (bio_integrity(bio))
+	if (unlikely(bio_integrity(bio) != NULL))
 		bio_integrity_trim(clone, 0, len);
 
 	return 0;
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 874462153f14..98f981026e4e 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -227,6 +227,12 @@ typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio)
 #define DM_TARGET_INTEGRITY		0x00000010
 #define dm_target_has_integrity(type)	((type)->features & DM_TARGET_INTEGRITY)
 
+/*
+ * A target passes integrity data to the lower device.
+ */
+#define DM_TARGET_PASSES_INTEGRITY	0x00000020
+#define dm_target_passes_integrity(type) ((type)->features & DM_TARGET_PASSES_INTEGRITY)
+
 struct dm_target {
 	struct dm_table *table;
 	struct target_type *type;