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

Depends on d7533ad0e132f92e75c1b2eb7c26387b25a583c1 being reverted.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
---
 drivers/md/md.c |   32 +++++++++++++++++++++++++++++++-
 1 files changed, 31 insertions(+), 1 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 45521da..b038581 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -3497,7 +3497,7 @@ static int do_md_run(mddev_t * mddev)
 	int err;
 	int chunk_size;
 	struct list_head *tmp;
-	mdk_rdev_t *rdev;
+	mdk_rdev_t *rdev, *prev;
 	struct gendisk *disk;
 	struct mdk_personality *pers;
 	char b[BDEVNAME_SIZE];
@@ -3759,6 +3759,35 @@ static int do_md_run(mddev_t * mddev)
 	sysfs_notify(&mddev->kobj, NULL, "sync_action");
 	sysfs_notify(&mddev->kobj, NULL, "degraded");
 	kobject_uevent(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE);
+
+	/* Data integrity passthrough not supported on RAID 4, 5 and 6 */
+	if (pers->level >= 4 && pers->level <= 6)
+		return 0;
+
+	prev = NULL;
+
+	rdev_for_each(rdev, tmp, mddev) {
+
+		if (prev && blk_integrity_compare(prev->bdev, rdev->bdev) < 0) {
+			printk(KERN_ERR "%s: %s %s Integrity mismatch!\n",
+			       __func__, prev->bdev->bd_disk->disk_name,
+			       rdev->bdev->bd_disk->disk_name);
+			return 0;
+		}
+
+		prev = rdev;
+	}
+
+	if (prev && bdev_get_integrity(prev->bdev)) {
+
+		if (blk_integrity_register(disk, prev->bdev->bd_disk->integrity))
+			printk(KERN_ERR "%s: %s Could not register integrity!\n",
+			       __func__, disk->disk_name);
+		else
+			printk(KERN_INFO "Enabling data integrity on %s\n",
+			       disk->disk_name);
+	}
+
 	return 0;
 }
 
@@ -3947,6 +3976,7 @@ static int do_md_stop(mddev_t * mddev, int mode, int is_open)
 		printk(KERN_INFO "md: %s switched to read-only mode.\n",
 			mdname(mddev));
 	err = 0;
+	blk_integrity_unregister(disk);
 	md_new_event(mddev);
 	sysfs_notify(&mddev->kobj, NULL, ...
[ message continues ]

On Sat, Sep 20, 2008 at 5:18 PM, Martin K. Petersen

Do you have a reference to the issues in supporting this?

Thanks,
Dan
--

[ message continues ]

Dan> Do you have a reference to the issues in supporting this?

Not really.

The protection information is an extra 8-bytes of stuff per sector.
But it comes down in a different buffer.  To do R-M-W effectively
we'll have to maintain a separate protection information stripe cache.
And we'll have to generate DIF checksums and reference tags for the
parity sectors going out.

Quite frankly it's a lot of ick and I haven't completely wrapped my
head around it yet.

-- 
Martin K. Petersen	Oracle Linux Engineering

--

[ message continues ]