1 files changed, 72 insertions, 67 deletions

diff --git a/drivers/md/dm-bio-prison.c b/drivers/md/dm-bio-prison.c
index d9d3f1c7b662..ca5771d3ffd7 100644
--- a/drivers/md/dm-bio-prison.c
+++ b/drivers/md/dm-bio-prison.c
@@ -16,7 +16,6 @@
 
 struct dm_bio_prison_cell {
         struct hlist_node list;
-        struct dm_bio_prison *prison;
         struct dm_cell_key key;
         struct bio *holder;
         struct bio_list bios;
@@ -87,6 +86,19 @@ void dm_bio_prison_destroy(struct dm_bio_prison *prison)
 }
 EXPORT_SYMBOL_GPL(dm_bio_prison_destroy);
 
+struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison, gfp_t gfp)
+{
+        return mempool_alloc(prison->cell_pool, gfp);
+}
+EXPORT_SYMBOL_GPL(dm_bio_prison_alloc_cell);
+
+void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
+                             struct dm_bio_prison_cell *cell)
+{
+        mempool_free(cell, prison->cell_pool);
+}
+EXPORT_SYMBOL_GPL(dm_bio_prison_free_cell);
+
 static uint32_t hash_key(struct dm_bio_prison *prison, struct dm_cell_key *key)
 {
         const unsigned long BIG_PRIME = 4294967291UL;
@@ -114,91 +126,86 @@ static struct dm_bio_prison_cell *__search_bucket(struct hlist_head *bucket,
         return NULL;
 }
 
-/*
- * This may block if a new cell needs allocating.  You must ensure that
- * cells will be unlocked even if the calling thread is blocked.
- *
- * Returns 1 if the cell was already held, 0 if @inmate is the new holder.
- */
-int dm_bio_detain(struct dm_bio_prison *prison, struct dm_cell_key *key,
-                  struct bio *inmate, struct dm_bio_prison_cell **ref)
+static void __setup_new_cell(struct dm_bio_prison *prison,
+                             struct dm_cell_key *key,
+                             struct bio *holder,
+                             uint32_t hash,
+                             struct dm_bio_prison_cell *cell)
 {
-        int r = 1;
-        unsigned long flags;
-        uint32_t hash = hash_key(prison, key);
-        struct dm_bio_prison_cell *cell, *cell2;
-
-        BUG_ON(hash > prison->nr_buckets);
-
-        spin_lock_irqsave(&prison->lock, flags);
-
-        cell = __search_bucket(prison->cells + hash, key);
-        if (cell) {
-                bio_list_add(&cell->bios, inmate);
-                goto out;
-        }
+        memcpy(&cell->key, key, sizeof(cell->key));
+        cell->holder = holder;
+        bio_list_init(&cell->bios);
+        hlist_add_head(&cell->list, prison->cells + hash);
+}
 
-        /*
-         * Allocate a new cell
-         */
-        spin_unlock_irqrestore(&prison->lock, flags);
-        cell2 = mempool_alloc(prison->cell_pool, GFP_NOIO);
-        spin_lock_irqsave(&prison->lock, flags);
+static int __bio_detain(struct dm_bio_prison *prison,
+                        struct dm_cell_key *key,
+                        struct bio *inmate,
+                        struct dm_bio_prison_cell *cell_prealloc,
+                        struct dm_bio_prison_cell **cell_result)
+{
+        uint32_t hash = hash_key(prison, key);
+        struct dm_bio_prison_cell *cell;
 
-        /*
-         * We've been unlocked, so we have to double check that
-         * nobody else has inserted this cell in the meantime.
-         */
         cell = __search_bucket(prison->cells + hash, key);
         if (cell) {
-                mempool_free(cell2, prison->cell_pool);
-                bio_list_add(&cell->bios, inmate);
-                goto out;
+                if (inmate)
+                        bio_list_add(&cell->bios, inmate);
+                *cell_result = cell;
+                return 1;
         }
 
-        /*
-         * Use new cell.
-         */
-        cell = cell2;
-
-        cell->prison = prison;
-        memcpy(&cell->key, key, sizeof(cell->key));
-        cell->holder = inmate;
-        bio_list_init(&cell->bios);
-        hlist_add_head(&cell->list, prison->cells + hash);
+        __setup_new_cell(prison, key, inmate, hash, cell_prealloc);
+        *cell_result = cell_prealloc;
+        return 0;
+}
 
-        r = 0;
+static int bio_detain(struct dm_bio_prison *prison,
+                      struct dm_cell_key *key,
+                      struct bio *inmate,
+                      struct dm_bio_prison_cell *cell_prealloc,
+                      struct dm_bio_prison_cell **cell_result)
+{
+        int r;
+        unsigned long flags;
 
-out:
+        spin_lock_irqsave(&prison->lock, flags);
+        r = __bio_detain(prison, key, inmate, cell_prealloc, cell_result);
         spin_unlock_irqrestore(&prison->lock, flags);
 
-        *ref = cell;
-
         return r;
 }
+
+int dm_bio_detain(struct dm_bio_prison *prison,
+                  struct dm_cell_key *key,
+                  struct bio *inmate,
+                  struct dm_bio_prison_cell *cell_prealloc,
+                  struct dm_bio_prison_cell **cell_result)
+{
+        return bio_detain(prison, key, inmate, cell_prealloc, cell_result);
+}
 EXPORT_SYMBOL_GPL(dm_bio_detain);
 
 /*
  * @inmates must have been initialised prior to this call
  */
-static void __cell_release(struct dm_bio_prison_cell *cell, struct bio_list *inmates)
+static void __cell_release(struct dm_bio_prison_cell *cell,
+                           struct bio_list *inmates)
 {
-        struct dm_bio_prison *prison = cell->prison;
-
         hlist_del(&cell->list);
 
         if (inmates) {
-                bio_list_add(inmates, cell->holder);
+                if (cell->holder)
+                        bio_list_add(inmates, cell->holder);
                 bio_list_merge(inmates, &cell->bios);
         }
-
-        mempool_free(cell, prison->cell_pool);
 }
 
-void dm_cell_release(struct dm_bio_prison_cell *cell, struct bio_list *bios)
+void dm_cell_release(struct dm_bio_prison *prison,
+                     struct dm_bio_prison_cell *cell,
+                     struct bio_list *bios)
 {
         unsigned long flags;
-        struct dm_bio_prison *prison = cell->prison;
 
         spin_lock_irqsave(&prison->lock, flags);
         __cell_release(cell, bios);
@@ -209,20 +216,18 @@ EXPORT_SYMBOL_GPL(dm_cell_release);
 /*
  * Sometimes we don't want the holder, just the additional bios.
  */
-static void __cell_release_no_holder(struct dm_bio_prison_cell *cell, struct bio_list *inmates)
+static void __cell_release_no_holder(struct dm_bio_prison_cell *cell,
+                                     struct bio_list *inmates)
 {
-        struct dm_bio_prison *prison = cell->prison;
-
         hlist_del(&cell->list);
         bio_list_merge(inmates, &cell->bios);
-
-        mempool_free(cell, prison->cell_pool);
 }
 
-void dm_cell_release_no_holder(struct dm_bio_prison_cell *cell, struct bio_list *inmates)
+void dm_cell_release_no_holder(struct dm_bio_prison *prison,
+                               struct dm_bio_prison_cell *cell,
+                               struct bio_list *inmates)
 {
         unsigned long flags;
-        struct dm_bio_prison *prison = cell->prison;
 
         spin_lock_irqsave(&prison->lock, flags);
         __cell_release_no_holder(cell, inmates);
@@ -230,9 +235,9 @@ void dm_cell_release_no_holder(struct dm_bio_prison_cell *cell, struct bio_list
 }
 EXPORT_SYMBOL_GPL(dm_cell_release_no_holder);
 
-void dm_cell_error(struct dm_bio_prison_cell *cell)
+void dm_cell_error(struct dm_bio_prison *prison,
+                   struct dm_bio_prison_cell *cell)
 {
-        struct dm_bio_prison *prison = cell->prison;
         struct bio_list bios;
         struct bio *bio;
         unsigned long flags;