[PATCH 4.19 84/86] dm integrity: fix integrity recalculation that is improperly skipped

Greg Kroah-Hartman
2020-07-27T14:12:56Z

From: Mikulas Patocka <mpatocka@redhat.com>

commit 5df96f2b9f58a5d2dc1f30fe7de75e197f2c25f2 upstream.

Commit adc0daad366b62ca1bce3e2958a40b0b71a8b8b3 ("dm: report suspended
device during destroy") broke integrity recalculation.

The problem is dm_suspended() returns true not only during suspend,
but also during resume. So this race condition could occur:
1. dm_integrity_resume calls queue_work(ic->recalc_wq, &ic->recalc_work)
2. integrity_recalc (&ic->recalc_work) preempts the current thread
3. integrity_recalc calls if (unlikely(dm_suspended(ic->ti))) goto unlock_ret;
4. integrity_recalc exits and no recalculating is done.

To fix this race condition, add a function dm_post_suspending that is
only true during the postsuspend phase and use it instead of
dm_suspended().

Signed-off-by: Mikulas Patocka <mpatocka redhat com>
Fixes: adc0daad366b ("dm: report suspended device during destroy")
Cc: stable vger kernel org # v4.18+
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/md/dm-integrity.c | 4 ++--
drivers/md/dm.c | 17 +++++++++++++++++
include/linux/device-mapper.h | 1 +
3 files changed, 20 insertions(+), 2 deletions(-)

--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -2068,7 +2068,7 @@ static void integrity_writer(struct work
unsigned prev_free_sectors;

/* the following test is not needed, but it tests the replay code */
- if (unlikely(dm_suspended(ic->ti)) && !ic->meta_dev)
+ if (unlikely(dm_post_suspending(ic->ti)) && !ic->meta_dev)
return;

spin_lock_irq(&ic->endio_wait.lock);
@@ -2127,7 +2127,7 @@ static void integrity_recalc(struct work

next_chunk:

- if (unlikely(dm_suspended(ic->ti)))
+ if (unlikely(dm_post_suspending(ic->ti)))
goto unlock_ret;

range.logical_sector = le64_to_cpu(ic->sb->recalc_sector);
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -141,6 +141,7 @@ EXPORT_SYMBOL_GPL(dm_bio_get_target_bio_
#define DMF_NOFLUSH_SUSPENDING 5
#define DMF_DEFERRED_REMOVE 6
#define DMF_SUSPENDED_INTERNALLY 7
+#define DMF_POST_SUSPENDING 8

#define DM_NUMA_NODE NUMA_NO_NODE
static int dm_numa_node = DM_NUMA_NODE;
@@ -2355,6 +2356,7 @@ static void __dm_destroy(struct mapped_d
if (!dm_suspended_md(md)) {
dm_table_presuspend_targets(map);
set_bit(DMF_SUSPENDED, &md->flags);
+ set_bit(DMF_POST_SUSPENDING, &md->flags);
dm_table_postsuspend_targets(map);
}
/* dm_put_live_table must be before msleep, otherwise deadlock is possible */
@@ -2680,7 +2682,9 @@ retry:
if (r)
goto out_unlock;

+ set_bit(DMF_POST_SUSPENDING, &md->flags);
dm_table_postsuspend_targets(map);
+ clear_bit(DMF_POST_SUSPENDING, &md->flags);

out_unlock:
mutex_unlock(&md->suspend_lock);
@@ -2777,7 +2781,9 @@ static void __dm_internal_suspend(struct
(void) __dm_suspend(md, map, suspend_flags, TASK_UNINTERRUPTIBLE,
DMF_SUSPENDED_INTERNALLY);

+ set_bit(DMF_POST_SUSPENDING, &md->flags);
dm_table_postsuspend_targets(map);
+ clear_bit(DMF_POST_SUSPENDING, &md->flags);
}

static void __dm_internal_resume(struct mapped_device *md)
@@ -2938,6 +2944,11 @@ int dm_suspended_md(struct mapped_device
return test_bit(DMF_SUSPENDED, &md->flags);
}

+static int dm_post_suspending_md(struct mapped_device *md)
+{
+ return test_bit(DMF_POST_SUSPENDING, &md->flags);
+}
+
int dm_suspended_internally_md(struct mapped_device *md)
{
return test_bit(DMF_SUSPENDED_INTERNALLY, &md->flags);
@@ -2954,6 +2965,12 @@ int dm_suspended(struct dm_target *ti)
}
EXPORT_SYMBOL_GPL(dm_suspended);

+int dm_post_suspending(struct dm_target *ti)
+{
+ return dm_post_suspending_md(dm_table_get_md(ti->table));
+}
+EXPORT_SYMBOL_GPL(dm_post_suspending);
+
int dm_noflush_suspending(struct dm_target *ti)
{
return __noflush_suspending(dm_table_get_md(ti->table));
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -419,6 +419,7 @@ const char *dm_device_name(struct mapped
int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
struct gendisk *dm_disk(struct mapped_device *md);
int dm_suspended(struct dm_target *ti);
+int dm_post_suspending(struct dm_target *ti);
int dm_noflush_suspending(struct dm_target *ti);
void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors);
void dm_remap_zone_report(struct dm_target *ti, struct bio *bio,