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

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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: Alex Lyakas <alex.lyakas@zadara.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/1702470271-16073-1-git-send-email-alex.lyakas@zadara.com
This commit is contained in:
Alex Lyakas 2023-12-13 14:24:31 +02:00 committed by Song Liu
parent af140f806a
commit dc1cc22ed5
1 changed files with 44 additions and 10 deletions
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54
drivers/md/md.c
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@ -1206,6 +1206,7 @@ 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);
@ -1343,8 +1344,9 @@ 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);
@ -1856,7 +1858,7 @@ 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);
@ -1952,13 +1954,15 @@ 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
@ -1979,8 +1983,38 @@ 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;
@ -2887,7 +2921,7 @@ 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);
err = mddev->pers->hot_add_disk(mddev, rdev);
if (err) {
md_kick_rdev_from_array(rdev);
@ -3824,7 +3858,7 @@ 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) {
@ -3839,7 +3873,7 @@ 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 %pg from array!\n",
rdev->bdev);
md_kick_rdev_from_array(rdev);
@ -6847,7 +6881,7 @@ int md_add_new_disk(struct mddev *mddev, struct mdu_disk_info_s *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