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-rw-r--r--block/blk-mq-tag.c204
1 files changed, 204 insertions, 0 deletions
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
new file mode 100644
index 00000000000..d64a02fb1f7
--- /dev/null
+++ b/block/blk-mq-tag.c
@@ -0,0 +1,204 @@
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/percpu_ida.h>
+
+#include <linux/blk-mq.h>
+#include "blk.h"
+#include "blk-mq.h"
+#include "blk-mq-tag.h"
+
+/*
+ * Per tagged queue (tag address space) map
+ */
+struct blk_mq_tags {
+ unsigned int nr_tags;
+ unsigned int nr_reserved_tags;
+ unsigned int nr_batch_move;
+ unsigned int nr_max_cache;
+
+ struct percpu_ida free_tags;
+ struct percpu_ida reserved_tags;
+};
+
+void blk_mq_wait_for_tags(struct blk_mq_tags *tags)
+{
+ int tag = blk_mq_get_tag(tags, __GFP_WAIT, false);
+ blk_mq_put_tag(tags, tag);
+}
+
+bool blk_mq_has_free_tags(struct blk_mq_tags *tags)
+{
+ return !tags ||
+ percpu_ida_free_tags(&tags->free_tags, nr_cpu_ids) != 0;
+}
+
+static unsigned int __blk_mq_get_tag(struct blk_mq_tags *tags, gfp_t gfp)
+{
+ int tag;
+
+ tag = percpu_ida_alloc(&tags->free_tags, gfp);
+ if (tag < 0)
+ return BLK_MQ_TAG_FAIL;
+ return tag + tags->nr_reserved_tags;
+}
+
+static unsigned int __blk_mq_get_reserved_tag(struct blk_mq_tags *tags,
+ gfp_t gfp)
+{
+ int tag;
+
+ if (unlikely(!tags->nr_reserved_tags)) {
+ WARN_ON_ONCE(1);
+ return BLK_MQ_TAG_FAIL;
+ }
+
+ tag = percpu_ida_alloc(&tags->reserved_tags, gfp);
+ if (tag < 0)
+ return BLK_MQ_TAG_FAIL;
+ return tag;
+}
+
+unsigned int blk_mq_get_tag(struct blk_mq_tags *tags, gfp_t gfp, bool reserved)
+{
+ if (!reserved)
+ return __blk_mq_get_tag(tags, gfp);
+
+ return __blk_mq_get_reserved_tag(tags, gfp);
+}
+
+static void __blk_mq_put_tag(struct blk_mq_tags *tags, unsigned int tag)
+{
+ BUG_ON(tag >= tags->nr_tags);
+
+ percpu_ida_free(&tags->free_tags, tag - tags->nr_reserved_tags);
+}
+
+static void __blk_mq_put_reserved_tag(struct blk_mq_tags *tags,
+ unsigned int tag)
+{
+ BUG_ON(tag >= tags->nr_reserved_tags);
+
+ percpu_ida_free(&tags->reserved_tags, tag);
+}
+
+void blk_mq_put_tag(struct blk_mq_tags *tags, unsigned int tag)
+{
+ if (tag >= tags->nr_reserved_tags)
+ __blk_mq_put_tag(tags, tag);
+ else
+ __blk_mq_put_reserved_tag(tags, tag);
+}
+
+static int __blk_mq_tag_iter(unsigned id, void *data)
+{
+ unsigned long *tag_map = data;
+ __set_bit(id, tag_map);
+ return 0;
+}
+
+void blk_mq_tag_busy_iter(struct blk_mq_tags *tags,
+ void (*fn)(void *, unsigned long *), void *data)
+{
+ unsigned long *tag_map;
+ size_t map_size;
+
+ map_size = ALIGN(tags->nr_tags, BITS_PER_LONG) / BITS_PER_LONG;
+ tag_map = kzalloc(map_size * sizeof(unsigned long), GFP_ATOMIC);
+ if (!tag_map)
+ return;
+
+ percpu_ida_for_each_free(&tags->free_tags, __blk_mq_tag_iter, tag_map);
+ if (tags->nr_reserved_tags)
+ percpu_ida_for_each_free(&tags->reserved_tags, __blk_mq_tag_iter,
+ tag_map);
+
+ fn(data, tag_map);
+ kfree(tag_map);
+}
+
+struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags,
+ unsigned int reserved_tags, int node)
+{
+ unsigned int nr_tags, nr_cache;
+ struct blk_mq_tags *tags;
+ int ret;
+
+ if (total_tags > BLK_MQ_TAG_MAX) {
+ pr_err("blk-mq: tag depth too large\n");
+ return NULL;
+ }
+
+ tags = kzalloc_node(sizeof(*tags), GFP_KERNEL, node);
+ if (!tags)
+ return NULL;
+
+ nr_tags = total_tags - reserved_tags;
+ nr_cache = nr_tags / num_possible_cpus();
+
+ if (nr_cache < BLK_MQ_TAG_CACHE_MIN)
+ nr_cache = BLK_MQ_TAG_CACHE_MIN;
+ else if (nr_cache > BLK_MQ_TAG_CACHE_MAX)
+ nr_cache = BLK_MQ_TAG_CACHE_MAX;
+
+ tags->nr_tags = total_tags;
+ tags->nr_reserved_tags = reserved_tags;
+ tags->nr_max_cache = nr_cache;
+ tags->nr_batch_move = max(1u, nr_cache / 2);
+
+ ret = __percpu_ida_init(&tags->free_tags, tags->nr_tags -
+ tags->nr_reserved_tags,
+ tags->nr_max_cache,
+ tags->nr_batch_move);
+ if (ret)
+ goto err_free_tags;
+
+ if (reserved_tags) {
+ /*
+ * With max_cahe and batch set to 1, the allocator fallbacks to
+ * no cached. It's fine reserved tags allocation is slow.
+ */
+ ret = __percpu_ida_init(&tags->reserved_tags, reserved_tags,
+ 1, 1);
+ if (ret)
+ goto err_reserved_tags;
+ }
+
+ return tags;
+
+err_reserved_tags:
+ percpu_ida_destroy(&tags->free_tags);
+err_free_tags:
+ kfree(tags);
+ return NULL;
+}
+
+void blk_mq_free_tags(struct blk_mq_tags *tags)
+{
+ percpu_ida_destroy(&tags->free_tags);
+ percpu_ida_destroy(&tags->reserved_tags);
+ kfree(tags);
+}
+
+ssize_t blk_mq_tag_sysfs_show(struct blk_mq_tags *tags, char *page)
+{
+ char *orig_page = page;
+ int cpu;
+
+ if (!tags)
+ return 0;
+
+ page += sprintf(page, "nr_tags=%u, reserved_tags=%u, batch_move=%u,"
+ " max_cache=%u\n", tags->nr_tags, tags->nr_reserved_tags,
+ tags->nr_batch_move, tags->nr_max_cache);
+
+ page += sprintf(page, "nr_free=%u, nr_reserved=%u\n",
+ percpu_ida_free_tags(&tags->free_tags, nr_cpu_ids),
+ percpu_ida_free_tags(&tags->reserved_tags, nr_cpu_ids));
+
+ for_each_possible_cpu(cpu) {
+ page += sprintf(page, " cpu%02u: nr_free=%u\n", cpu,
+ percpu_ida_free_tags(&tags->free_tags, cpu));
+ }
+
+ return page - orig_page;
+}