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authorAlex Shi <alex.shi@linaro.org>2017-03-20 12:03:10 +0800
committerAlex Shi <alex.shi@linaro.org>2017-03-20 12:03:10 +0800
commite0d60977f25c7a33b2acda240a1d121bf0a35deb (patch)
tree4f930533fa1e36e0ec75ee8bcaa82d2320985a2c /drivers/md/dm.c
parent4304568925f8191755da36df5c61abb69db9b1b0 (diff)
parent1c563c0006661025d7a6c9bc85fc889a4e8a1c06 (diff)
downloadlinux-linaro-stable-lsk-v4.4-17.03-android.tar.gz
Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-androidlsk-v4.4-17.03-android
Diffstat (limited to 'drivers/md/dm.c')
-rw-r--r--drivers/md/dm.c55
1 files changed, 55 insertions, 0 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 3384a3eef917..397f0454100b 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1467,11 +1467,62 @@ void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors)
}
EXPORT_SYMBOL_GPL(dm_accept_partial_bio);
+/*
+ * Flush current->bio_list when the target map method blocks.
+ * This fixes deadlocks in snapshot and possibly in other targets.
+ */
+struct dm_offload {
+ struct blk_plug plug;
+ struct blk_plug_cb cb;
+};
+
+static void flush_current_bio_list(struct blk_plug_cb *cb, bool from_schedule)
+{
+ struct dm_offload *o = container_of(cb, struct dm_offload, cb);
+ struct bio_list list;
+ struct bio *bio;
+
+ INIT_LIST_HEAD(&o->cb.list);
+
+ if (unlikely(!current->bio_list))
+ return;
+
+ list = *current->bio_list;
+ bio_list_init(current->bio_list);
+
+ while ((bio = bio_list_pop(&list))) {
+ struct bio_set *bs = bio->bi_pool;
+ if (unlikely(!bs) || bs == fs_bio_set) {
+ bio_list_add(current->bio_list, bio);
+ continue;
+ }
+
+ spin_lock(&bs->rescue_lock);
+ bio_list_add(&bs->rescue_list, bio);
+ queue_work(bs->rescue_workqueue, &bs->rescue_work);
+ spin_unlock(&bs->rescue_lock);
+ }
+}
+
+static void dm_offload_start(struct dm_offload *o)
+{
+ blk_start_plug(&o->plug);
+ o->cb.callback = flush_current_bio_list;
+ list_add(&o->cb.list, &current->plug->cb_list);
+}
+
+static void dm_offload_end(struct dm_offload *o)
+{
+ list_del(&o->cb.list);
+ blk_finish_plug(&o->plug);
+}
+
static void __map_bio(struct dm_target_io *tio)
{
int r;
sector_t sector;
struct mapped_device *md;
+ struct dm_offload o;
struct bio *clone = &tio->clone;
struct dm_target *ti = tio->ti;
@@ -1484,7 +1535,11 @@ static void __map_bio(struct dm_target_io *tio)
*/
atomic_inc(&tio->io->io_count);
sector = clone->bi_iter.bi_sector;
+
+ dm_offload_start(&o);
r = ti->type->map(ti, clone);
+ dm_offload_end(&o);
+
if (r == DM_MAPIO_REMAPPED) {
/* the bio has been remapped so dispatch it */