[PATCH 3/7] dm: handle failures in dm_table_set_restrictions

Benjamin Marzinski
2025-03-09T22:29:13Z

If dm_table_set_restrictions() fails while swapping tables,
device-mapper will continue using the previous table. It must be sure to
leave the mapped_device in it's previous state on failure. Otherwise
device-mapper could end up using the old table with settings from the
unused table.

Do not update the mapped device in dm_set_zones_restrictions(). Wait
till after dm_table_set_restrictions() is sure to succeed to update the
md zoned settings. Do the same with the dax settings, and if
dm_revalidate_zones() fails, restore the original queue limits.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
---
drivers/md/dm-table.c | 24 ++++++++++++++++--------
drivers/md/dm-zone.c | 26 ++++++++++++++++++--------
drivers/md/dm.h | 1 +
3 files changed, 35 insertions(+), 16 deletions(-)

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 0ef5203387b2..4003e84af11d 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1836,6 +1836,7 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
struct queue_limits *limits)
{
int r;
+ struct queue_limits old_limits;

if (!dm_table_supports_nowait(t))
limits->features &= ~BLK_FEAT_NOWAIT;
@@ -1862,16 +1863,11 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
if (dm_table_supports_flush(t))
limits->features |= BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA;

- if (dm_table_supports_dax(t, device_not_dax_capable)) {
+ if (dm_table_supports_dax(t, device_not_dax_capable))
limits->features |= BLK_FEAT_DAX;
- if (dm_table_supports_dax(t, device_not_dax_synchronous_capable))
- set_dax_synchronous(t->md->dax_dev);
- } else
+ else
limits->features &= ~BLK_FEAT_DAX;

- if (dm_table_any_dev_attr(t, device_dax_write_cache_enabled, NULL))
- dax_write_cache(t->md->dax_dev, true);
-
/* For a zoned table, setup the zone related queue attributes. */
if (IS_ENABLED(CONFIG_BLK_DEV_ZONED) &&
(limits->features & BLK_FEAT_ZONED)) {
@@ -1883,6 +1879,7 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
if (dm_table_supports_atomic_writes(t))
limits->features |= BLK_FEAT_ATOMIC_WRITES;

+ old_limits = q->limits;
r = queue_limits_set(q, limits);
if (r)
return r;
@@ -1894,10 +1891,21 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
if (IS_ENABLED(CONFIG_BLK_DEV_ZONED) &&
(limits->features & BLK_FEAT_ZONED)) {
r = dm_revalidate_zones(t, q);
- if (r)
+ if (r) {
+ queue_limits_set(q, &old_limits);
return r;
+ }
}

+ if (IS_ENABLED(CONFIG_BLK_DEV_ZONED))
+ dm_finalize_zone_settings(t, limits);
+
+ if (dm_table_supports_dax(t, device_not_dax_synchronous_capable))
+ set_dax_synchronous(t->md->dax_dev);
+
+ if (dm_table_any_dev_attr(t, device_dax_write_cache_enabled, NULL))
+ dax_write_cache(t->md->dax_dev, true);
+
dm_update_crypto_profile(q, t);
return 0;
}
diff --git a/drivers/md/dm-zone.c b/drivers/md/dm-zone.c
index 20edd3fabbab..681058feb63b 100644
--- a/drivers/md/dm-zone.c
+++ b/drivers/md/dm-zone.c
@@ -340,12 +340,8 @@ int dm_set_zones_restrictions(struct dm_table *t, struct request_queue *q,
* mapped device queue as needing zone append emulation.
*/
WARN_ON_ONCE(queue_is_mq(q));
- if (dm_table_supports_zone_append(t)) {
- clear_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
- } else {
- set_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
+ if (!dm_table_supports_zone_append(t))
lim->max_hw_zone_append_sectors = 0;
- }

/*
* Determine the max open and max active zone limits for the mapped
@@ -383,9 +379,6 @@ int dm_set_zones_restrictions(struct dm_table *t, struct request_queue *q,
lim->zone_write_granularity = 0;
lim->chunk_sectors = 0;
lim->features &= ~BLK_FEAT_ZONED;
- clear_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
- md->nr_zones = 0;
- disk->nr_zones = 0;
return 0;
}

@@ -408,6 +401,23 @@ int dm_set_zones_restrictions(struct dm_table *t, struct request_queue *q,
return 0;
}

+void dm_finalize_zone_settings(struct dm_table *t, struct queue_limits *lim)
+{
+ struct mapped_device *md = t->md;
+
+ if (lim->features & BLK_FEAT_ZONED) {
+ if (dm_table_supports_zone_append(t))
+ clear_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
+ else
+ set_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
+ } else {
+ clear_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
+ md->nr_zones = 0;
+ md->disk->nr_zones = 0;
+ }
+}
+
+
/*
* IO completion callback called from clone_endio().
*/
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index a0a8ff119815..e5d3a9f46a91 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -102,6 +102,7 @@ int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t);
int dm_set_zones_restrictions(struct dm_table *t, struct request_queue *q,
struct queue_limits *lim);
int dm_revalidate_zones(struct dm_table *t, struct request_queue *q);
+void dm_finalize_zone_settings(struct dm_table *t, struct queue_limits *lim);
void dm_zone_endio(struct dm_io *io, struct bio *clone);
#ifdef CONFIG_BLK_DEV_ZONED
int dm_blk_report_zones(struct gendisk *disk, sector_t sector,
--
2.48.1