[02/11] block: add support for carrying a stream ID in a bio
diff mbox

Message ID 1457107853-8689-3-git-send-email-axboe@fb.com
State New
Headers show

Commit Message

Jens Axboe March 4, 2016, 4:10 p.m. UTC
The top bits of bio->bi_flags are reserved for keeping the
allocation pool, set aside the next 16 bits for carrying
a stream ID. That leaves us with support for 64k - 1 streams,
0 is reserved as a "stream not set" value.

Add helpers for setting/getting stream ID of a bio.

Signed-off-by: Jens Axboe <axboe@fb.com>
---
 block/bio.c               |  5 ++++
 block/blk-core.c          |  4 ++++
 include/linux/blk_types.h | 60 ++++++++++++++++++++++++++++++++++-------------
 3 files changed, 53 insertions(+), 16 deletions(-)

Patch
diff mbox

diff --git a/block/bio.c b/block/bio.c
index cf7591551b17..d42e69c23271 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -584,6 +584,7 @@  void __bio_clone_fast(struct bio *bio, struct bio *bio_src)
 	bio->bi_rw = bio_src->bi_rw;
 	bio->bi_iter = bio_src->bi_iter;
 	bio->bi_io_vec = bio_src->bi_io_vec;
+	bio_set_streamid(bio, bio_get_streamid(bio_src));
 }
 EXPORT_SYMBOL(__bio_clone_fast);
 
@@ -689,6 +690,7 @@  integrity_clone:
 		}
 	}
 
+	bio_set_streamid(bio, bio_get_streamid(bio_src));
 	return bio;
 }
 EXPORT_SYMBOL(bio_clone_bioset);
@@ -2037,6 +2039,9 @@  static void __init biovec_init_slabs(void)
 
 static int __init init_bio(void)
 {
+	BUILD_BUG_ON(BIO_FLAG_LAST > ((8 * sizeof(unsigned int)) -
+			BIO_POOL_BITS - BIO_STREAM_BITS));
+
 	bio_slab_max = 2;
 	bio_slab_nr = 0;
 	bio_slabs = kzalloc(bio_slab_max * sizeof(struct bio_slab), GFP_KERNEL);
diff --git a/block/blk-core.c b/block/blk-core.c
index b83d29755b5a..e4b12693c567 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2071,6 +2071,10 @@  blk_qc_t generic_make_request(struct bio *bio)
 		struct request_queue *q = bdev_get_queue(bio->bi_bdev);
 
 		if (likely(blk_queue_enter(q, false) == 0)) {
+			if (bio_streamid_valid(bio))
+				blk_add_trace_msg(q, "StreamID=%u",
+							bio_get_streamid(bio));
+
 			ret = q->make_request_fn(q, bio);
 
 			blk_queue_exit(q);
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 86a38ea1823f..fc63a82a9944 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -112,21 +112,23 @@  struct bio {
 /*
  * bio flags
  */
-#define BIO_SEG_VALID	1	/* bi_phys_segments valid */
-#define BIO_CLONED	2	/* doesn't own data */
-#define BIO_BOUNCED	3	/* bio is a bounce bio */
-#define BIO_USER_MAPPED 4	/* contains user pages */
-#define BIO_NULL_MAPPED 5	/* contains invalid user pages */
-#define BIO_QUIET	6	/* Make BIO Quiet */
-#define BIO_CHAIN	7	/* chained bio, ->bi_remaining in effect */
-#define BIO_REFFED	8	/* bio has elevated ->bi_cnt */
-
-/*
- * Flags starting here get preserved by bio_reset() - this includes
- * BIO_POOL_IDX()
- */
-#define BIO_RESET_BITS	13
-#define BIO_OWNS_VEC	13	/* bio_free() should free bvec */
+enum {
+	BIO_SEG_VALID	= 0,	/* bi_phys_segments valid */
+	BIO_CLONED,		/* doesn't own data */
+	BIO_BOUNCED,		/* bio is a bounce bio */
+	BIO_USER_MAPPED,	/* contains user pages */
+	BIO_NULL_MAPPED,	/* contains invalid user pages */
+	BIO_QUIET,		/* Mnake BIO Quiet */
+	BIO_CHAIN,		/* chained bio, ->bi_remaining in effect */
+	BIO_REFFED,		/* bio has elevated ->bi_cnt */
+	BIO_OWNS_VEC,		/* bio_free() should free bvec */
+	BIO_FLAG_LAST,		/* end of bits */
+	/*
+	 * Flags starting here get preserved by bio_reset() - this includes
+	 * BIO_POOL_IDX()
+	 */
+	BIO_RESET_BITS = BIO_FLAG_LAST,
+};
 
 /*
  * top 4 bits of bio flags indicate the pool this bio came from
@@ -134,9 +136,35 @@  struct bio {
 #define BIO_POOL_BITS		(4)
 #define BIO_POOL_NONE		((1UL << BIO_POOL_BITS) - 1)
 #define BIO_POOL_OFFSET		(32 - BIO_POOL_BITS)
-#define BIO_POOL_MASK		(1UL << BIO_POOL_OFFSET)
 #define BIO_POOL_IDX(bio)	((bio)->bi_flags >> BIO_POOL_OFFSET)
 
+/*
+ * after the pool bits, next 16 bits are for the stream id
+ */
+#define BIO_STREAM_BITS		(16)
+#define BIO_STREAM_OFFSET	(BIO_POOL_OFFSET - BIO_STREAM_BITS)
+#define BIO_STREAM_MASK		((1 << BIO_STREAM_BITS) - 1)
+
+static inline unsigned long streamid_to_flags(unsigned int id)
+{
+	return (unsigned long) (id & BIO_STREAM_MASK) << BIO_STREAM_OFFSET;
+}
+
+static inline void bio_set_streamid(struct bio *bio, unsigned int id)
+{
+	bio->bi_flags |= streamid_to_flags(id);
+}
+
+static inline unsigned int bio_get_streamid(struct bio *bio)
+{
+	return (bio->bi_flags >> BIO_STREAM_OFFSET) & BIO_STREAM_MASK;
+}
+
+static inline bool bio_streamid_valid(struct bio *bio)
+{
+	return bio_get_streamid(bio) != 0;
+}
+
 #endif /* CONFIG_BLOCK */
 
 /*