Re: [PATCH] md/raid: only permit hot-add of compatible integrity profiles

[NeilBrown]

On Thu, Jan 14 2016, Dan Williams wrote:

> It is not safe for an integrity profile to be changed while i/o is
> in-flight in the queue.  Prevent adding new disks or otherwise online
> spares to an array if the device has an incompatible integrity profile.
>
> The original change to the blk_integrity_unregister implementation in
> md, commmit c7bfced9a671 "md: suspend i/o during runtime
> blk_integrity_unregister" introduced an immediate hang regression.
>
> This policy of disallowing changes the integrity profile once one has
> been established is shared with DM.

Thanks Dan.  That looks like it should address the issues and seems to
make sense.
If it passes my smoke-testing I'll include it in my merge-window pull
request tomorrow.

NeilBrown


>
> Here is an abbreviated log from a test run that:
> 1/ Creates a degraded raid1 with an integrity-enabled device (pmem0s) [   59.076127]
> 2/ Tries to add an integrity-disabled device (pmem1m) [   90.489209]
> 3/ Retries with an integrity-enabled device (pmem1s) [  205.671277]
>
> [   59.076127] md/raid1:md0: active with 1 out of 2 mirrors
> [   59.078302] md: data integrity enabled on md0
> [..]
> [   90.489209] md0: incompatible integrity profile for pmem1m
> [..]
> [  205.671277] md: super_written gets error=-5
> [  205.677386] md/raid1:md0: Disk failure on pmem1m, disabling device.
> [  205.677386] md/raid1:md0: Operation continuing on 1 devices.
> [  205.683037] RAID1 conf printout:
> [  205.684699]  --- wd:1 rd:2
> [  205.685972]  disk 0, wo:0, o:1, dev:pmem0s
> [  205.687562]  disk 1, wo:1, o:1, dev:pmem1s
> [  205.691717] md: recovery of RAID array md0
>
> Fixes: c7bfced9a671 ("md: suspend i/o during runtime blk_integrity_unregister")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
> Reported-by: NeilBrown <neilb@xxxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> ---
>  drivers/md/md.c        |   28 ++++++++++++++++------------
>  drivers/md/md.h        |    2 +-
>  drivers/md/multipath.c |    6 +++---
>  drivers/md/raid1.c     |    6 +++---
>  drivers/md/raid10.c    |    6 +++---
>  5 files changed, 26 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 61aacab424cf..b1e1f6b95782 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -2017,28 +2017,32 @@ int md_integrity_register(struct mddev *mddev)
>  }
>  EXPORT_SYMBOL(md_integrity_register);
>  
> -/* Disable data integrity if non-capable/non-matching disk is being added */
> -void md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev)
> +/*
> + * Attempt to add an rdev, but only if it is consistent with the current
> + * integrity profile
> + */
> +int md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev)
>  {
>  	struct blk_integrity *bi_rdev;
>  	struct blk_integrity *bi_mddev;
> +	char name[BDEVNAME_SIZE];
>  
>  	if (!mddev->gendisk)
> -		return;
> +		return 0;
>  
>  	bi_rdev = bdev_get_integrity(rdev->bdev);
>  	bi_mddev = blk_get_integrity(mddev->gendisk);
>  
>  	if (!bi_mddev) /* nothing to do */
> -		return;
> -	if (rdev->raid_disk < 0) /* skip spares */
> -		return;
> -	if (bi_rdev && blk_integrity_compare(mddev->gendisk,
> -					     rdev->bdev->bd_disk) >= 0)
> -		return;
> -	WARN_ON_ONCE(!mddev->suspended);
> -	printk(KERN_NOTICE "disabling data integrity on %s\n", mdname(mddev));
> -	blk_integrity_unregister(mddev->gendisk);
> +		return 0;
> +
> +	if (blk_integrity_compare(mddev->gendisk, rdev->bdev->bd_disk) != 0) {
> +		printk(KERN_NOTICE "%s: incompatible integrity profile for %s\n",
> +				mdname(mddev), bdevname(rdev->bdev, name));
> +		return -ENXIO;
> +	}
> +
> +	return 0;
>  }
>  EXPORT_SYMBOL(md_integrity_add_rdev);
>  
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index ca0b643fe3c1..dfa57b41541b 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -657,7 +657,7 @@ extern void md_wait_for_blocked_rdev(struct md_rdev *rdev, struct mddev *mddev);
>  extern void md_set_array_sectors(struct mddev *mddev, sector_t array_sectors);
>  extern int md_check_no_bitmap(struct mddev *mddev);
>  extern int md_integrity_register(struct mddev *mddev);
> -extern void md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev);
> +extern int md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev);
>  extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);
>  
>  extern void mddev_init(struct mddev *mddev);
> diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c
> index 7331a80d89f1..0a72ab6e6c20 100644
> --- a/drivers/md/multipath.c
> +++ b/drivers/md/multipath.c
> @@ -257,6 +257,9 @@ static int multipath_add_disk(struct mddev *mddev, struct md_rdev *rdev)
>  			disk_stack_limits(mddev->gendisk, rdev->bdev,
>  					  rdev->data_offset << 9);
>  
> +			err = md_integrity_add_rdev(rdev, mddev);
> +			if (err)
> +				break;
>  			spin_lock_irq(&conf->device_lock);
>  			mddev->degraded--;
>  			rdev->raid_disk = path;
> @@ -264,9 +267,6 @@ static int multipath_add_disk(struct mddev *mddev, struct md_rdev *rdev)
>  			spin_unlock_irq(&conf->device_lock);
>  			rcu_assign_pointer(p->rdev, rdev);
>  			err = 0;
> -			mddev_suspend(mddev);
> -			md_integrity_add_rdev(rdev, mddev);
> -			mddev_resume(mddev);
>  			break;
>  		}
>  
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index e2169ff6e0f0..c4b913409226 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -1589,6 +1589,9 @@ static int raid1_add_disk(struct mddev *mddev, struct md_rdev *rdev)
>  	if (mddev->recovery_disabled == conf->recovery_disabled)
>  		return -EBUSY;
>  
> +	if (md_integrity_add_rdev(rdev, mddev))
> +		return -ENXIO;
> +
>  	if (rdev->raid_disk >= 0)
>  		first = last = rdev->raid_disk;
>  
> @@ -1632,9 +1635,6 @@ static int raid1_add_disk(struct mddev *mddev, struct md_rdev *rdev)
>  			break;
>  		}
>  	}
> -	mddev_suspend(mddev);
> -	md_integrity_add_rdev(rdev, mddev);
> -	mddev_resume(mddev);
>  	if (mddev->queue && blk_queue_discard(bdev_get_queue(rdev->bdev)))
>  		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
>  	print_conf(conf);
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index 84e597e1c489..ce959b4ae4df 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -1698,6 +1698,9 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
>  	if (rdev->saved_raid_disk < 0 && !_enough(conf, 1, -1))
>  		return -EINVAL;
>  
> +	if (md_integrity_add_rdev(rdev, mddev))
> +		return -ENXIO;
> +
>  	if (rdev->raid_disk >= 0)
>  		first = last = rdev->raid_disk;
>  
> @@ -1739,9 +1742,6 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
>  		rcu_assign_pointer(p->rdev, rdev);
>  		break;
>  	}
> -	mddev_suspend(mddev);
> -	md_integrity_add_rdev(rdev, mddev);
> -	mddev_resume(mddev);
>  	if (mddev->queue && blk_queue_discard(bdev_get_queue(rdev->bdev)))
>  		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
>

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