Hi Mike
Please submit this to Linus and to RHEL-8.
Mikulas
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
The patch adc0daad366b62ca1bce3e2958a40b0b71a8b8b3 broke recalculation on
dm-integrity. The patch replaces a private variable "suspending" with a
call to "dm_suspended".
The problem is that dm_suspended returns true not only during suspend, but
also during resume. 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.
In order to fix this race condition, we stop using dm_suspended and start
using the variable "suspending" (that is only set during suspend, not
during resume).
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Fixes: adc0daad366b ("dm: report suspended device during destroy")
Cc: stable@xxxxxxxxxxxxxxx # v4.18+
---
drivers/md/dm-integrity.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
Index: linux-2.6/drivers/md/dm-integrity.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-integrity.c 2020-06-29 14:49:59.000000000 +0200
+++ linux-2.6/drivers/md/dm-integrity.c 2020-07-22 15:48:49.000000000 +0200
@@ -204,13 +204,12 @@ struct dm_integrity_c {
__u8 log2_blocks_per_bitmap_bit;
unsigned char mode;
+ int suspending;
int failed;
struct crypto_shash *internal_hash;
- struct dm_target *ti;
-
/* these variables are locked with endio_wait.lock */
struct rb_root in_progress;
struct list_head wait_list;
@@ -2420,7 +2419,7 @@ 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 (READ_ONCE(ic->suspending) && !ic->meta_dev)
return;
spin_lock_irq(&ic->endio_wait.lock);
@@ -2481,7 +2480,7 @@ static void integrity_recalc(struct work
next_chunk:
- if (unlikely(dm_suspended(ic->ti)))
+ if (unlikely(READ_ONCE(ic->suspending)))
goto unlock_ret;
range.logical_sector = le64_to_cpu(ic->sb->recalc_sector);
@@ -2909,6 +2908,8 @@ static void dm_integrity_postsuspend(str
del_timer_sync(&ic->autocommit_timer);
+ WRITE_ONCE(ic->suspending, 1);
+
if (ic->recalc_wq)
drain_workqueue(ic->recalc_wq);
@@ -2937,6 +2938,8 @@ static void dm_integrity_postsuspend(str
#endif
}
+ WRITE_ONCE(ic->suspending, 0);
+
BUG_ON(!RB_EMPTY_ROOT(&ic->in_progress));
ic->journal_uptodate = true;
@@ -3767,7 +3770,6 @@ static int dm_integrity_ctr(struct dm_ta
}
ti->private = ic;
ti->per_io_data_size = sizeof(struct dm_integrity_io);
- ic->ti = ti;
ic->in_progress = RB_ROOT;
INIT_LIST_HEAD(&ic->wait_list);
--
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