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dm raid: fix failed takeover/reshapes by keeping raid set frozen 

Superblock updates where bogus causing some takovers/reshapes to fail.

Introduce new runtime flag (RT_FLAG_KEEP_RS_FROZEN) to keep a raid set
frozen when a layout change was requested.  Userpace will immediately
reload the table w/o the flags requesting such change once they made it
to the superblocks and any change of recovery/reshape offsets has to be
avoided until after read.

Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Heinz Mauelshagen 2016-06-14 15:23:13 -04:00 committed by Mike Snitzer
parent 4257e085e2
commit 6e20902e8f
1 changed files with 57 additions and 30 deletions
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87
drivers/md/dm-raid.c
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@ -190,6 +190,7 @@ struct raid_dev {
#define RT_FLAG_RS_BITMAP_LOADED 2
#define RT_FLAG_UPDATE_SBS 3
#define RT_FLAG_RESHAPE_RS 4
#define RT_FLAG_KEEP_RS_FROZEN 5
/* Array elements of 64 bit needed for rebuild/write_mostly bits */
#define DISKS_ARRAY_ELEMS ((MAX_RAID_DEVICES + (sizeof(uint64_t) * 8 - 1)) / sizeof(uint64_t) / 8)
@ -2727,6 +2728,7 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
return r;
set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
set_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags);
rs_set_new(rs);
} else if (rs_reshape_requested(rs)) {
if (rs_is_reshaping(rs)) {
@ -2767,13 +2769,19 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
* Would cause allocations in raid1->check_reshape
* though, thus more issues with potential failures
*/
else if (rs_is_raid1(rs))
else if (rs_is_raid1(rs)) {
set_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags);
rs->md.raid_disks = rs->raid_disks;
}
if (test_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags)) {
set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
set_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags);
}
if (rs->md.raid_disks < rs->raid_disks)
set_bit(MD_ARRAY_FIRST_USE, &rs->md.flags);
set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
rs_set_cur(rs);
} else
rs_set_cur(rs);
@ -3231,9 +3239,11 @@ static void raid_postsuspend(struct dm_target *ti)
{
struct raid_set *rs = ti->private;
mddev_suspend(&rs->md);
rs->md.ro = 1;
clear_bit(RT_FLAG_RS_RESUMED, &rs->runtime_flags);
if (test_and_clear_bit(RT_FLAG_RS_RESUMED, &rs->runtime_flags)) {
if (!rs->md.suspended)
mddev_suspend(&rs->md);
rs->md.ro = 1;
}
}
static void attempt_restore_of_faulty_devices(struct raid_set *rs)
@ -3308,6 +3318,18 @@ static int __load_dirty_region_bitmap(struct raid_set *rs)
return r;
}
/* Enforce updating all superblocks */
static void rs_update_sbs(struct raid_set *rs)
{
struct mddev *mddev = &rs->md;
int ro = mddev->ro;
set_bit(MD_CHANGE_DEVS, &mddev->flags);
mddev->ro = 0;
md_update_sb(mddev, 1);
mddev->ro = ro;
}
/*
* Reshape changes raid algorithm of @rs to new one within personality
* (e.g. raid6_zr -> raid6_nc), changes stripe size, adds/removes
@ -3356,9 +3378,12 @@ static int rs_start_reshape(struct raid_set *rs)
if (!mddev->suspended)
mddev_suspend(mddev);
mddev->ro = 0;
md_update_sb(mddev, 1);
mddev->ro = 1;
/*
* Now reshape got set up, update superblocks to
* reflect the fact so that a table reload will
* access proper superblock content in the ctr.
*/
rs_update_sbs(rs);
return 0;
}
@ -3375,22 +3400,12 @@ static int raid_preresume(struct dm_target *ti)
/*
* The superblocks need to be updated on disk if the
* array is new or __load_dirty_region_bitmap will overwrite them
* in core with old data.
*
* In case the array got modified (takeover/reshape/resize)
* or the data offsets on the component devices changed, they
* have to be updated as well.
*
* Have to switch to readwrite and back in order to
* allow for the superblock updates.
* array is new or new devices got added (thus zeroed
* out by userspace) or __load_dirty_region_bitmap
* will overwrite them in core with old data or fail.
*/
if (test_and_clear_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags)) {
set_bit(MD_CHANGE_DEVS, &mddev->flags);
mddev->ro = 0;
md_update_sb(mddev, 1);
mddev->ro = 1;
}
if (test_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags))
rs_update_sbs(rs);
/*
* Disable/enable discard support on raid set after any
@ -3449,14 +3464,26 @@ static void raid_resume(struct dm_target *ti)
* devices are reachable again.
*/
attempt_restore_of_faulty_devices(rs);
} else {
mddev->ro = 0;
mddev->in_sync = 0;
/*
* When passing in flags to the ctr, we expect userspace
* to reset them because they made it to the superblocks
* and reload the mapping anyway.
*
* -> only unfreeze recovery in case of a table reload or
* we'll have a bogus recovery/reshape position
* retrieved from the superblock by the ctr because
* the ongoing recovery/reshape will change it after read.
*/
if (!test_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags))
clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
if (mddev->suspended)
mddev_resume(mddev);
}
mddev->ro = 0;
mddev->in_sync = 0;
clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
if (mddev->suspended)
mddev_resume(mddev);
}
static struct target_type raid_target = {