blk-mq: abstract tag allocation out into sbitmap library

This is a generally useful data structure, so make it available to
anyone else who might want to use it. It's also a nice cleanup
separating the allocation logic from the rest of the tag handling logic.

The code is behind a new Kconfig option, CONFIG_SBITMAP, which is only
selected by CONFIG_BLOCK for now.

This should be a complete noop functionality-wise.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 2 insertions, 7 deletions

diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 60ef14cbcd2d..2575779cf13f 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -2,6 +2,7 @@
 #define BLK_MQ_H
 
 #include <linux/blkdev.h>
+#include <linux/sbitmap.h>
 
 struct blk_mq_tags;
 struct blk_flush_queue;
@@ -12,12 +13,6 @@ struct blk_mq_cpu_notifier {
         int (*notify)(void *data, unsigned long action, unsigned int cpu);
 };
 
-struct blk_mq_ctxmap {
-        unsigned int size;
-        unsigned int bits_per_word;
-        struct blk_align_bitmap *map;
-};
-
 struct blk_mq_hw_ctx {
         struct {
                 spinlock_t              lock;
@@ -37,7 +32,7 @@ struct blk_mq_hw_ctx {
 
         void                    *driver_data;
 
-        struct blk_mq_ctxmap    ctx_map;
+        struct sbitmap          ctx_map;
 
         struct blk_mq_ctx       **ctxs;
         unsigned int            nr_ctx;