Merge branch 'misc' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild

[linux-2.6-block.git] / block / blk-mq-tag.c

diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 60c9d4a93fe470ced7471cd8653d8a00fc8922d7..d53a764b05eacde776a4454054795d1c0277d676 100644 (file)
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -140,35 +140,39 @@ static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx,
        return atomic_read(&hctx->nr_active) < depth;
 }
 
-static int __bt_get_word(struct blk_align_bitmap *bm, unsigned int last_tag)
+static int __bt_get_word(struct blk_align_bitmap *bm, unsigned int last_tag,
+                        bool nowrap)
 {
-       int tag, org_last_tag, end;
-       bool wrap = last_tag != 0;
+       int tag, org_last_tag = last_tag;
 
-       org_last_tag = last_tag;
-       end = bm->depth;
-       do {
-restart:
-               tag = find_next_zero_bit(&bm->word, end, last_tag);
-               if (unlikely(tag >= end)) {
+       while (1) {
+               tag = find_next_zero_bit(&bm->word, bm->depth, last_tag);
+               if (unlikely(tag >= bm->depth)) {
                        /*
-                        * We started with an offset, start from 0 to
+                        * We started with an offset, and we didn't reset the
+                        * offset to 0 in a failure case, so start from 0 to
                         * exhaust the map.
                         */
-                       if (wrap) {
-                               wrap = false;
-                               end = org_last_tag;
-                               last_tag = 0;
-                               goto restart;
+                       if (org_last_tag && last_tag && !nowrap) {
+                               last_tag = org_last_tag = 0;
+                               continue;
                        }
                        return -1;
                }
+
+               if (!test_and_set_bit(tag, &bm->word))
+                       break;
+
                last_tag = tag + 1;
-       } while (test_and_set_bit(tag, &bm->word));
+               if (last_tag >= bm->depth - 1)
+                       last_tag = 0;
+       }
 
        return tag;
 }
 
+#define BT_ALLOC_RR(tags) (tags->alloc_policy == BLK_TAG_ALLOC_RR)
+
 /*
  * Straight forward bitmap tag implementation, where each bit is a tag
  * (cleared == free, and set == busy). The small twist is using per-cpu
@@ -181,7 +185,7 @@ restart:
  * until the map is exhausted.
  */
 static int __bt_get(struct blk_mq_hw_ctx *hctx, struct blk_mq_bitmap_tags *bt,
-                   unsigned int *tag_cache)
+                   unsigned int *tag_cache, struct blk_mq_tags *tags)
 {
        unsigned int last_tag, org_last_tag;
        int index, i, tag;
@@ -193,15 +197,24 @@ static int __bt_get(struct blk_mq_hw_ctx *hctx, struct blk_mq_bitmap_tags *bt,
        index = TAG_TO_INDEX(bt, last_tag);
 
        for (i = 0; i < bt->map_nr; i++) {
-               tag = __bt_get_word(&bt->map[index], TAG_TO_BIT(bt, last_tag));
+               tag = __bt_get_word(&bt->map[index], TAG_TO_BIT(bt, last_tag),
+                                   BT_ALLOC_RR(tags));
                if (tag != -1) {
                        tag += (index << bt->bits_per_word);
                        goto done;
                }
 
-               last_tag = 0;
-               if (++index >= bt->map_nr)
+               /*
+                * Jump to next index, and reset the last tag to be the
+                * first tag of that index
+                */
+               index++;
+               last_tag = (index << bt->bits_per_word);
+
+               if (index >= bt->map_nr) {
                        index = 0;
+                       last_tag = 0;
+               }
        }
 
        *tag_cache = 0;
@@ -212,7 +225,7 @@ static int __bt_get(struct blk_mq_hw_ctx *hctx, struct blk_mq_bitmap_tags *bt,
         * up using the specific cached tag.
         */
 done:
-       if (tag == org_last_tag) {
+       if (tag == org_last_tag || unlikely(BT_ALLOC_RR(tags))) {
                last_tag = tag + 1;
                if (last_tag >= bt->depth - 1)
                        last_tag = 0;
@@ -241,13 +254,13 @@ static struct bt_wait_state *bt_wait_ptr(struct blk_mq_bitmap_tags *bt,
 static int bt_get(struct blk_mq_alloc_data *data,
                struct blk_mq_bitmap_tags *bt,
                struct blk_mq_hw_ctx *hctx,
-               unsigned int *last_tag)
+               unsigned int *last_tag, struct blk_mq_tags *tags)
 {
        struct bt_wait_state *bs;
        DEFINE_WAIT(wait);
        int tag;
 
-       tag = __bt_get(hctx, bt, last_tag);
+       tag = __bt_get(hctx, bt, last_tag, tags);
        if (tag != -1)
                return tag;
 
@@ -258,7 +271,7 @@ static int bt_get(struct blk_mq_alloc_data *data,
        do {
                prepare_to_wait(&bs->wait, &wait, TASK_UNINTERRUPTIBLE);
 
-               tag = __bt_get(hctx, bt, last_tag);
+               tag = __bt_get(hctx, bt, last_tag, tags);
                if (tag != -1)
                        break;
 
@@ -273,7 +286,7 @@ static int bt_get(struct blk_mq_alloc_data *data,
                 * Retry tag allocation after running the hardware queue,
                 * as running the queue may also have found completions.
                 */
-               tag = __bt_get(hctx, bt, last_tag);
+               tag = __bt_get(hctx, bt, last_tag, tags);
                if (tag != -1)
                        break;
 
@@ -304,7 +317,7 @@ static unsigned int __blk_mq_get_tag(struct blk_mq_alloc_data *data)
        int tag;
 
        tag = bt_get(data, &data->hctx->tags->bitmap_tags, data->hctx,
-                       &data->ctx->last_tag);
+                       &data->ctx->last_tag, data->hctx->tags);
        if (tag >= 0)
                return tag + data->hctx->tags->nr_reserved_tags;
 
@@ -320,7 +333,8 @@ static unsigned int __blk_mq_get_reserved_tag(struct blk_mq_alloc_data *data)
                return BLK_MQ_TAG_FAIL;
        }
 
-       tag = bt_get(data, &data->hctx->tags->breserved_tags, NULL, &zero);
+       tag = bt_get(data, &data->hctx->tags->breserved_tags, NULL, &zero,
+               data->hctx->tags);
        if (tag < 0)
                return BLK_MQ_TAG_FAIL;
 
@@ -392,7 +406,8 @@ void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, unsigned int tag,
 
                BUG_ON(real_tag >= tags->nr_tags);
                bt_clear_tag(&tags->bitmap_tags, real_tag);
-               *last_tag = real_tag;
+               if (likely(tags->alloc_policy == BLK_TAG_ALLOC_FIFO))
+                       *last_tag = real_tag;
        } else {
                BUG_ON(tag >= tags->nr_reserved_tags);
                bt_clear_tag(&tags->breserved_tags, tag);
@@ -509,6 +524,7 @@ static int bt_alloc(struct blk_mq_bitmap_tags *bt, unsigned int depth,
        bt->bs = kzalloc(BT_WAIT_QUEUES * sizeof(*bt->bs), GFP_KERNEL);
        if (!bt->bs) {
                kfree(bt->map);
+               bt->map = NULL;
                return -ENOMEM;
        }
 
@@ -529,10 +545,12 @@ static void bt_free(struct blk_mq_bitmap_tags *bt)
 }
 
 static struct blk_mq_tags *blk_mq_init_bitmap_tags(struct blk_mq_tags *tags,
-                                                  int node)
+                                                  int node, int alloc_policy)
 {
        unsigned int depth = tags->nr_tags - tags->nr_reserved_tags;
 
+       tags->alloc_policy = alloc_policy;
+
        if (bt_alloc(&tags->bitmap_tags, depth, node, false))
                goto enomem;
        if (bt_alloc(&tags->breserved_tags, tags->nr_reserved_tags, node, true))
@@ -546,7 +564,8 @@ enomem:
 }
 
 struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags,
-                                    unsigned int reserved_tags, int node)
+                                    unsigned int reserved_tags,
+                                    int node, int alloc_policy)
 {
        struct blk_mq_tags *tags;
 
@@ -562,7 +581,7 @@ struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags,
        tags->nr_tags = total_tags;
        tags->nr_reserved_tags = reserved_tags;
 
-       return blk_mq_init_bitmap_tags(tags, node);
+       return blk_mq_init_bitmap_tags(tags, node, alloc_policy);
 }
 
 void blk_mq_free_tags(struct blk_mq_tags *tags)