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authorMike Snitzer <snitzer@redhat.com>2022-02-17 23:40:02 -0500
committerMike Snitzer <snitzer@redhat.com>2022-02-21 15:19:08 -0500
commit9f6dc633761006f974701d4c88da71ab68670749 (patch)
treefcabdaea0e9f0c3306be15f39ee4dd9f71978c73 /drivers/md/dm.c
parentbcd2be763252f3a4d5fc4d6008d4d96c601ee74b (diff)
downloadlinux-9f6dc633761006f974701d4c88da71ab68670749.tar.bz2
dm: interlock pending dm_io and dm_wait_for_bios_completion
Commit d208b89401e0 ("dm: fix mempool NULL pointer race when completing IO") didn't go far enough. When bio_end_io_acct ends the count of in-flight I/Os may reach zero and the DM device may be suspended. There is a possibility that the suspend races with dm_stats_account_io. Fix this by adding percpu "pending_io" counters to track outstanding dm_io. Move kicking of suspend queue to dm_io_dec_pending(). Also, rename md_in_flight_bios() to dm_in_flight_bios() and update it to iterate all pending_io counters. Fixes: d208b89401e0 ("dm: fix mempool NULL pointer race when completing IO") Cc: stable@vger.kernel.org Co-developed-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm.c')
-rw-r--r--drivers/md/dm.c35
1 files changed, 23 insertions, 12 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index ab9cc91931f9..18329b33e8cd 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -508,10 +508,6 @@ static void end_io_acct(struct mapped_device *md, struct bio *bio,
dm_stats_account_io(&md->stats, bio_data_dir(bio),
bio->bi_iter.bi_sector, bio_sectors(bio),
true, duration, stats_aux);
-
- /* nudge anyone waiting on suspend queue */
- if (unlikely(wq_has_sleeper(&md->wait)))
- wake_up(&md->wait);
}
static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio)
@@ -530,6 +526,7 @@ static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio)
io->magic = DM_IO_MAGIC;
io->status = 0;
atomic_set(&io->io_count, 1);
+ this_cpu_inc(*md->pending_io);
io->orig_bio = bio;
io->md = md;
spin_lock_init(&io->endio_lock);
@@ -827,6 +824,12 @@ void dm_io_dec_pending(struct dm_io *io, blk_status_t error)
stats_aux = io->stats_aux;
free_io(md, io);
end_io_acct(md, bio, start_time, &stats_aux);
+ smp_wmb();
+ this_cpu_dec(*md->pending_io);
+
+ /* nudge anyone waiting on suspend queue */
+ if (unlikely(wq_has_sleeper(&md->wait)))
+ wake_up(&md->wait);
if (io_error == BLK_STS_DM_REQUEUE)
return;
@@ -1569,6 +1572,11 @@ static void cleanup_mapped_device(struct mapped_device *md)
blk_cleanup_disk(md->disk);
}
+ if (md->pending_io) {
+ free_percpu(md->pending_io);
+ md->pending_io = NULL;
+ }
+
cleanup_srcu_struct(&md->io_barrier);
mutex_destroy(&md->suspend_lock);
@@ -1671,6 +1679,10 @@ static struct mapped_device *alloc_dev(int minor)
if (!md->wq)
goto bad;
+ md->pending_io = alloc_percpu(unsigned long);
+ if (!md->pending_io)
+ goto bad;
+
dm_stats_init(&md->stats);
/* Populate the mapping, nobody knows we exist yet */
@@ -2078,16 +2090,13 @@ void dm_put(struct mapped_device *md)
}
EXPORT_SYMBOL_GPL(dm_put);
-static bool md_in_flight_bios(struct mapped_device *md)
+static bool dm_in_flight_bios(struct mapped_device *md)
{
int cpu;
- struct block_device *part = dm_disk(md)->part0;
- long sum = 0;
+ unsigned long sum = 0;
- for_each_possible_cpu(cpu) {
- sum += part_stat_local_read_cpu(part, in_flight[0], cpu);
- sum += part_stat_local_read_cpu(part, in_flight[1], cpu);
- }
+ for_each_possible_cpu(cpu)
+ sum += *per_cpu_ptr(md->pending_io, cpu);
return sum != 0;
}
@@ -2100,7 +2109,7 @@ static int dm_wait_for_bios_completion(struct mapped_device *md, unsigned int ta
while (true) {
prepare_to_wait(&md->wait, &wait, task_state);
- if (!md_in_flight_bios(md))
+ if (!dm_in_flight_bios(md))
break;
if (signal_pending_state(task_state, current)) {
@@ -2112,6 +2121,8 @@ static int dm_wait_for_bios_completion(struct mapped_device *md, unsigned int ta
}
finish_wait(&md->wait, &wait);
+ smp_rmb();
+
return r;
}