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 <nks@daterainc.com>
Signed-off-by: Kent Overstreet <kmo@daterainc.com>

1 files changed, 7 insertions, 6 deletions

diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index fc14ba3f6d05..3e880869871f 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -248,7 +248,7 @@ static void bch_data_insert_keys(struct closure *cl)
                 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 @@ static void bch_data_invalidate(struct closure *cl)
         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 @@ static void bch_data_insert_endio(struct bio *bio, int error)
                 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 @@ static void bch_data_insert_start(struct closure *cl)
                 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 @@ static void bch_data_insert_start(struct closure *cl)
         } 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 @@ err:
                 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 @@ static inline struct search *search_alloc(struct bio *bio,
         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;
 }