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authorMikulas Patocka <mpatocka@redhat.com>2020-02-17 07:43:03 -0500
committerMike Snitzer <snitzer@redhat.com>2020-02-25 12:06:07 -0500
commit53770f0ec5fd417429775ba006bc4abe14002335 (patch)
treef4e1a8ff13effc8ea2e9bc51d90d4c97921da1e6 /drivers/md/dm-integrity.c
parentdm integrity: fix recalculation when moving from journal mode to bitmap mode (diff)
downloadlinux-dev-53770f0ec5fd417429775ba006bc4abe14002335.tar.xz
linux-dev-53770f0ec5fd417429775ba006bc4abe14002335.zip
dm integrity: fix a deadlock due to offloading to an incorrect workqueue
If we need to perform synchronous I/O in dm_integrity_map_continue(), we must make sure that we are not in the map function - in order to avoid the deadlock due to bio queuing in generic_make_request. To avoid the deadlock, we offload the request to metadata_wq. However, metadata_wq also processes metadata updates for write requests. If there are too many requests that get offloaded to metadata_wq at the beginning of dm_integrity_map_continue, the workqueue metadata_wq becomes clogged and the system is incapable of processing any metadata updates. This causes a deadlock because all the requests that need to do metadata updates wait for metadata_wq to proceed and metadata_wq waits inside wait_and_add_new_range until some existing request releases its range lock (which doesn't happen because the range lock is released after metadata update). In order to fix the deadlock, we create a new workqueue offload_wq and offload requests to it - so that processing of offload_wq is independent from processing of metadata_wq. Fixes: 7eada909bfd7 ("dm: add integrity target") Cc: stable@vger.kernel.org # v4.12+ Reported-by: Heinz Mauelshagen <heinzm@redhat.com> Tested-by: Heinz Mauelshagen <heinzm@redhat.com> Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm-integrity.c')
-rw-r--r--drivers/md/dm-integrity.c19
1 files changed, 15 insertions, 4 deletions
diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index 166727a47cef..6b6c3e1deaa8 100644
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -212,6 +212,7 @@ struct dm_integrity_c {
struct list_head wait_list;
wait_queue_head_t endio_wait;
struct workqueue_struct *wait_wq;
+ struct workqueue_struct *offload_wq;
unsigned char commit_seq;
commit_id_t commit_ids[N_COMMIT_IDS];
@@ -1439,7 +1440,7 @@ static void dec_in_flight(struct dm_integrity_io *dio)
dio->range.logical_sector += dio->range.n_sectors;
bio_advance(bio, dio->range.n_sectors << SECTOR_SHIFT);
INIT_WORK(&dio->work, integrity_bio_wait);
- queue_work(ic->wait_wq, &dio->work);
+ queue_work(ic->offload_wq, &dio->work);
return;
}
do_endio_flush(ic, dio);
@@ -1865,7 +1866,7 @@ static void dm_integrity_map_continue(struct dm_integrity_io *dio, bool from_map
if (need_sync_io && from_map) {
INIT_WORK(&dio->work, integrity_bio_wait);
- queue_work(ic->metadata_wq, &dio->work);
+ queue_work(ic->offload_wq, &dio->work);
return;
}
@@ -2501,7 +2502,7 @@ static void bitmap_block_work(struct work_struct *w)
dio->range.n_sectors, BITMAP_OP_TEST_ALL_SET)) {
remove_range(ic, &dio->range);
INIT_WORK(&dio->work, integrity_bio_wait);
- queue_work(ic->wait_wq, &dio->work);
+ queue_work(ic->offload_wq, &dio->work);
} else {
block_bitmap_op(ic, ic->journal, dio->range.logical_sector,
dio->range.n_sectors, BITMAP_OP_SET);
@@ -2524,7 +2525,7 @@ static void bitmap_block_work(struct work_struct *w)
remove_range(ic, &dio->range);
INIT_WORK(&dio->work, integrity_bio_wait);
- queue_work(ic->wait_wq, &dio->work);
+ queue_work(ic->offload_wq, &dio->work);
}
queue_delayed_work(ic->commit_wq, &ic->bitmap_flush_work, ic->bitmap_flush_interval);
@@ -3843,6 +3844,14 @@ static int dm_integrity_ctr(struct dm_target *ti, unsigned argc, char **argv)
goto bad;
}
+ ic->offload_wq = alloc_workqueue("dm-integrity-offload", WQ_MEM_RECLAIM,
+ METADATA_WORKQUEUE_MAX_ACTIVE);
+ if (!ic->offload_wq) {
+ ti->error = "Cannot allocate workqueue";
+ r = -ENOMEM;
+ goto bad;
+ }
+
ic->commit_wq = alloc_workqueue("dm-integrity-commit", WQ_MEM_RECLAIM, 1);
if (!ic->commit_wq) {
ti->error = "Cannot allocate workqueue";
@@ -4147,6 +4156,8 @@ static void dm_integrity_dtr(struct dm_target *ti)
destroy_workqueue(ic->metadata_wq);
if (ic->wait_wq)
destroy_workqueue(ic->wait_wq);
+ if (ic->offload_wq)
+ destroy_workqueue(ic->offload_wq);
if (ic->commit_wq)
destroy_workqueue(ic->commit_wq);
if (ic->writer_wq)