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dm: flush queued bios when process blocks to avoid deadlock

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am: 21582cd0b6

Change-Id: I23e32d9f39d07a9a6178688aa78f7b0a10718408
This commit is contained in:
Mikulas Patocka
2017-03-18 11:36:57 +00:00
committed by android-build-merger
parent f2b56a7662 21582cd0b6
commit 04ab239838
1 changed files with 55 additions and 0 deletions
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55
drivers/md/dm.c
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@@ -972,10 +972,61 @@ 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 dm_offload o;
struct bio *clone = &tio->clone;
struct dm_target *ti = tio->ti;
@@ -988,7 +1039,11 @@ 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 */