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Commit 351b37b8 authored by Alex Lyakas's avatar Alex Lyakas Committed by Greg Kroah-Hartman
Browse files

md: Whenassemble the array, consult the superblock of the freshest device 



[ Upstream commit dc1cc22ed58f11d58d8553c5ec5f11cbfc3e3039 ]

Upon assembling the array, both kernel and mdadm allow the devices to have event
counter difference of 1, and still consider them as up-to-date.
However, a device whose event count is behind by 1, may in fact not be up-to-date,
and array resync with such a device may cause data corruption.
To avoid this, consult the superblock of the freshest device about the status
of a device, whose event counter is behind by 1.

Signed-off-by: default avatarAlex Lyakas <alex.lyakas@zadara.com>
Signed-off-by: default avatarSong Liu <song@kernel.org>
Link: https://lore.kernel.org/r/1702470271-16073-1-git-send-email-alex.lyakas@zadara.com


Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 6f2cd02f

drivers/md/md.c

+44 −10
Original line number Diff line number Diff line
@@ -1098,6 +1098,7 @@ struct super_type { 
					  struct md_rdev *refdev,

					  int minor_version);

	int		    (*validate_super)(struct mddev *mddev,

					      struct md_rdev *freshest,

					      struct md_rdev *rdev);

	void		    (*sync_super)(struct mddev *mddev,

					  struct md_rdev *rdev);
@@ -1236,8 +1237,9 @@ static int super_90_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor 


/*

 * validate_super for 0.90.0

 * note: we are not using "freshest" for 0.9 superblock

 */

static int super_90_validate(struct mddev *mddev, struct md_rdev *rdev)

static int super_90_validate(struct mddev *mddev, struct md_rdev *freshest, struct md_rdev *rdev)

{

	mdp_disk_t *desc;

	mdp_super_t *sb = page_address(rdev->sb_page);
@@ -1752,7 +1754,7 @@ static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_ 
	return ret;

}



static int super_1_validate(struct mddev *mddev, struct md_rdev *rdev)

static int super_1_validate(struct mddev *mddev, struct md_rdev *freshest, struct md_rdev *rdev)

{

	struct mdp_superblock_1 *sb = page_address(rdev->sb_page);

	__u64 ev1 = le64_to_cpu(sb->events);
@@ -1848,13 +1850,15 @@ static int super_1_validate(struct mddev *mddev, struct md_rdev *rdev) 
		}

	} else if (mddev->pers == NULL) {

		/* Insist of good event counter while assembling, except for

		 * spares (which don't need an event count) */

		++ev1;

		 * spares (which don't need an event count).

		 * Similar to mdadm, we allow event counter difference of 1

		 * from the freshest device.

		 */

		if (rdev->desc_nr >= 0 &&

		    rdev->desc_nr < le32_to_cpu(sb->max_dev) &&

		    (le16_to_cpu(sb->dev_roles[rdev->desc_nr]) < MD_DISK_ROLE_MAX ||

		     le16_to_cpu(sb->dev_roles[rdev->desc_nr]) == MD_DISK_ROLE_JOURNAL))

			if (ev1 < mddev->events)

			if (ev1 + 1 < mddev->events)

				return -EINVAL;

	} else if (mddev->bitmap) {

		/* If adding to array with a bitmap, then we can accept an
@@ -1875,8 +1879,38 @@ static int super_1_validate(struct mddev *mddev, struct md_rdev *rdev) 
		    rdev->desc_nr >= le32_to_cpu(sb->max_dev)) {

			role = MD_DISK_ROLE_SPARE;

			rdev->desc_nr = -1;

		} else

		} else if (mddev->pers == NULL && freshest && ev1 < mddev->events) {

			/*

			 * If we are assembling, and our event counter is smaller than the

			 * highest event counter, we cannot trust our superblock about the role.

			 * It could happen that our rdev was marked as Faulty, and all other

			 * superblocks were updated with +1 event counter.

			 * Then, before the next superblock update, which typically happens when

			 * remove_and_add_spares() removes the device from the array, there was

			 * a crash or reboot.

			 * If we allow current rdev without consulting the freshest superblock,

			 * we could cause data corruption.

			 * Note that in this case our event counter is smaller by 1 than the

			 * highest, otherwise, this rdev would not be allowed into array;

			 * both kernel and mdadm allow event counter difference of 1.

			 */

			struct mdp_superblock_1 *freshest_sb = page_address(freshest->sb_page);

			u32 freshest_max_dev = le32_to_cpu(freshest_sb->max_dev);



			if (rdev->desc_nr >= freshest_max_dev) {

				/* this is unexpected, better not proceed */

				pr_warn("md: %s: rdev[%pg]: desc_nr(%d) >= freshest(%pg)->sb->max_dev(%u)\n",

						mdname(mddev), rdev->bdev, rdev->desc_nr,

						freshest->bdev, freshest_max_dev);

				return -EUCLEAN;

			}



			role = le16_to_cpu(freshest_sb->dev_roles[rdev->desc_nr]);

			pr_debug("md: %s: rdev[%pg]: role=%d(0x%x) according to freshest %pg\n",

				     mdname(mddev), rdev->bdev, role, role, freshest->bdev);

		} else {

			role = le16_to_cpu(sb->dev_roles[rdev->desc_nr]);

		}

		switch(role) {

		case MD_DISK_ROLE_SPARE: /* spare */

			break;
@@ -2780,7 +2814,7 @@ static int add_bound_rdev(struct md_rdev *rdev) 
		 * and should be added immediately.

		 */

		super_types[mddev->major_version].

			validate_super(mddev, rdev);

			validate_super(mddev, NULL/*freshest*/, rdev);

		if (add_journal)

			mddev_suspend(mddev);

		err = mddev->pers->hot_add_disk(mddev, rdev);
@@ -3690,7 +3724,7 @@ static int analyze_sbs(struct mddev *mddev) 
	}



	super_types[mddev->major_version].

		validate_super(mddev, freshest);

		validate_super(mddev, NULL/*freshest*/, freshest);



	i = 0;

	rdev_for_each_safe(rdev, tmp, mddev) {
@@ -3705,7 +3739,7 @@ static int analyze_sbs(struct mddev *mddev) 
		}

		if (rdev != freshest) {

			if (super_types[mddev->major_version].

			    validate_super(mddev, rdev)) {

			    validate_super(mddev, freshest, rdev)) {

				pr_warn("md: kicking non-fresh %s from array!\n",

					bdevname(rdev->bdev,b));

				md_kick_rdev_from_array(rdev);
@@ -6610,7 +6644,7 @@ static int add_new_disk(struct mddev *mddev, mdu_disk_info_t *info) 
			rdev->saved_raid_disk = rdev->raid_disk;

		} else

			super_types[mddev->major_version].

				validate_super(mddev, rdev);

				validate_super(mddev, NULL/*freshest*/, rdev);

		if ((info->state & (1<<MD_DISK_SYNC)) &&

		     rdev->raid_disk != info->raid_disk) {

			/* This was a hot-add request, but events doesn't