bcache: Fix moving_gc deadlocking with a foreground write
Deadlock happened because a foreground write slept, waiting for a bucket
to be allocated. Normally the gc would mark buckets available for invalidation.
But the moving_gc was stuck waiting for outstanding writes to complete.
These writes used the bcache_wq, the same queue foreground writes used.
This fix gives moving_gc its own work queue, so it was still finish moving
even if foreground writes are stuck waiting for allocation. It also makes
work queue a parameter to the data_insert path, so moving_gc can use its
workqueue for writes.
Signed-off-by: Nicholas Swenson <[email protected]>
Signed-off-by: Kent Overstreet <[email protected]>
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index a4c7306..6d814f4 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -628,6 +628,8 @@
/* Number of moving GC bios in flight */
struct semaphore moving_in_flight;
+ struct workqueue_struct *moving_gc_wq;
+
struct btree *root;
#ifdef CONFIG_BCACHE_DEBUG
diff --git a/drivers/md/bcache/movinggc.c b/drivers/md/bcache/movinggc.c
index 9eb60d1..8c72051 100644
--- a/drivers/md/bcache/movinggc.c
+++ b/drivers/md/bcache/movinggc.c
@@ -115,7 +115,7 @@
closure_call(&op->cl, bch_data_insert, NULL, cl);
}
- continue_at(cl, write_moving_finish, system_wq);
+ continue_at(cl, write_moving_finish, op->wq);
}
static void read_moving_submit(struct closure *cl)
@@ -125,7 +125,7 @@
bch_submit_bbio(bio, io->op.c, &io->w->key, 0);
- continue_at(cl, write_moving, system_wq);
+ continue_at(cl, write_moving, io->op.wq);
}
static void read_moving(struct cache_set *c)
@@ -160,6 +160,7 @@
io->w = w;
io->op.inode = KEY_INODE(&w->key);
io->op.c = c;
+ io->op.wq = c->moving_gc_wq;
moving_init(io);
bio = &io->bio.bio;
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index fc14ba3..3e880869 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -248,7 +248,7 @@
atomic_dec_bug(journal_ref);
if (!op->insert_data_done)
- continue_at(cl, bch_data_insert_start, bcache_wq);
+ continue_at(cl, bch_data_insert_start, op->wq);
bch_keylist_free(&op->insert_keys);
closure_return(cl);
@@ -297,7 +297,7 @@
op->insert_data_done = true;
bio_put(bio);
out:
- continue_at(cl, bch_data_insert_keys, bcache_wq);
+ continue_at(cl, bch_data_insert_keys, op->wq);
}
static void bch_data_insert_error(struct closure *cl)
@@ -340,7 +340,7 @@
if (op->writeback)
op->error = error;
else if (!op->replace)
- set_closure_fn(cl, bch_data_insert_error, bcache_wq);
+ set_closure_fn(cl, bch_data_insert_error, op->wq);
else
set_closure_fn(cl, NULL, NULL);
}
@@ -376,7 +376,7 @@
if (bch_keylist_realloc(&op->insert_keys,
3 + (op->csum ? 1 : 0),
op->c))
- continue_at(cl, bch_data_insert_keys, bcache_wq);
+ continue_at(cl, bch_data_insert_keys, op->wq);
k = op->insert_keys.top;
bkey_init(k);
@@ -413,7 +413,7 @@
} while (n != bio);
op->insert_data_done = true;
- continue_at(cl, bch_data_insert_keys, bcache_wq);
+ continue_at(cl, bch_data_insert_keys, op->wq);
err:
/* bch_alloc_sectors() blocks if s->writeback = true */
BUG_ON(op->writeback);
@@ -442,7 +442,7 @@
bio_put(bio);
if (!bch_keylist_empty(&op->insert_keys))
- continue_at(cl, bch_data_insert_keys, bcache_wq);
+ continue_at(cl, bch_data_insert_keys, op->wq);
else
closure_return(cl);
}
@@ -824,6 +824,7 @@
s->iop.error = 0;
s->iop.flags = 0;
s->iop.flush_journal = (bio->bi_rw & (REQ_FLUSH|REQ_FUA)) != 0;
+ s->iop.wq = bcache_wq;
return s;
}
diff --git a/drivers/md/bcache/request.h b/drivers/md/bcache/request.h
index 39f21db..c117c40 100644
--- a/drivers/md/bcache/request.h
+++ b/drivers/md/bcache/request.h
@@ -7,6 +7,7 @@
struct closure cl;
struct cache_set *c;
struct bio *bio;
+ struct workqueue_struct *wq;
unsigned inode;
uint16_t write_point;
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index fb34327..ddfde38 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1356,6 +1356,8 @@
bch_bset_sort_state_free(&c->sort);
free_pages((unsigned long) c->uuids, ilog2(bucket_pages(c)));
+ if (c->moving_gc_wq)
+ destroy_workqueue(c->moving_gc_wq);
if (c->bio_split)
bioset_free(c->bio_split);
if (c->fill_iter)
@@ -1522,6 +1524,7 @@
!(c->fill_iter = mempool_create_kmalloc_pool(1, iter_size)) ||
!(c->bio_split = bioset_create(4, offsetof(struct bbio, bio))) ||
!(c->uuids = alloc_bucket_pages(GFP_KERNEL, c)) ||
+ !(c->moving_gc_wq = create_workqueue("bcache_gc")) ||
bch_journal_alloc(c) ||
bch_btree_cache_alloc(c) ||
bch_open_buckets_alloc(c) ||
