block: Avoid deadlocks with bio allocation by stacking drivers

[firefly-linux-kernel-4.4.55.git] / include / linux / bio.h

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 820e7aaad4fdbbf432b188b083662b5015bd3905..b31036ff779f216d78b8b6ad7c7f8c9b43dacff7 100644 (file)
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -298,39 +298,6 @@ static inline int bio_associate_current(struct bio *bio) { return -ENOENT; }
 static inline void bio_disassociate_task(struct bio *bio) { }
 #endif /* CONFIG_BLK_CGROUP */
 
-/*
- * bio_set is used to allow other portions of the IO system to
- * allocate their own private memory pools for bio and iovec structures.
- * These memory pools in turn all allocate from the bio_slab
- * and the bvec_slabs[].
- */
-#define BIO_POOL_SIZE 2
-#define BIOVEC_NR_POOLS 6
-#define BIOVEC_MAX_IDX (BIOVEC_NR_POOLS - 1)
-
-struct bio_set {
-       struct kmem_cache *bio_slab;
-       unsigned int front_pad;
-
-       mempool_t *bio_pool;
-#if defined(CONFIG_BLK_DEV_INTEGRITY)
-       mempool_t *bio_integrity_pool;
-#endif
-       mempool_t *bvec_pool;
-};
-
-struct biovec_slab {
-       int nr_vecs;
-       char *name;
-       struct kmem_cache *slab;
-};
-
-/*
- * a small number of entries is fine, not going to be performance critical.
- * basically we just need to survive
- */
-#define BIO_SPLIT_ENTRIES 2
-
 #ifdef CONFIG_HIGHMEM
 /*
  * remember never ever reenable interrupts between a bvec_kmap_irq and
@@ -527,6 +494,48 @@ static inline struct bio *bio_list_get(struct bio_list *bl)
        return bio;
 }
 
+/*
+ * bio_set is used to allow other portions of the IO system to
+ * allocate their own private memory pools for bio and iovec structures.
+ * These memory pools in turn all allocate from the bio_slab
+ * and the bvec_slabs[].
+ */
+#define BIO_POOL_SIZE 2
+#define BIOVEC_NR_POOLS 6
+#define BIOVEC_MAX_IDX (BIOVEC_NR_POOLS - 1)
+
+struct bio_set {
+       struct kmem_cache *bio_slab;
+       unsigned int front_pad;
+
+       mempool_t *bio_pool;
+#if defined(CONFIG_BLK_DEV_INTEGRITY)
+       mempool_t *bio_integrity_pool;
+#endif
+       mempool_t *bvec_pool;
+
+       /*
+        * Deadlock avoidance for stacking block drivers: see comments in
+        * bio_alloc_bioset() for details
+        */
+       spinlock_t              rescue_lock;
+       struct bio_list         rescue_list;
+       struct work_struct      rescue_work;
+       struct workqueue_struct *rescue_workqueue;
+};
+
+struct biovec_slab {
+       int nr_vecs;
+       char *name;
+       struct kmem_cache *slab;
+};
+
+/*
+ * a small number of entries is fine, not going to be performance critical.
+ * basically we just need to survive
+ */
+#define BIO_SPLIT_ENTRIES 2
+
 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 
 #define bip_vec_idx(bip, idx)  (&(bip->bip_vec[(idx)]))