xen/blkback: separate ring information out of struct xen_blkif

Split per ring information to an new structure "xen_blkif_ring", so that one vbd
device can be associated with one or more rings/hardware queues.

Introduce 'pers_gnts_lock' to protect the pool of persistent grants since we
may have multi backend threads.

This patch is a preparation for supporting multi hardware queues/rings.

Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
v2: Align the variables in the structure.

1 files changed, 33 insertions, 23 deletions

diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index 68e87a037b99..dbdf4164c83f 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -269,34 +269,50 @@ struct persistent_gnt {
 	struct list_head remove_node;
 };
 
+/* Per-ring information. */
+struct xen_blkif_ring {
+	/* Physical parameters of the comms window. */
+	unsigned int		irq;
+	union blkif_back_rings	blk_rings;
+	void			*blk_ring;
+	/* Private fields. */
+	spinlock_t		blk_ring_lock;
+
+	wait_queue_head_t	wq;
+	atomic_t		inflight;
+	/* One thread per blkif ring. */
+	struct task_struct	*xenblkd;
+	unsigned int		waiting_reqs;
+
+	/* List of all 'pending_req' available */
+	struct list_head	pending_free;
+	/* And its spinlock. */
+	spinlock_t		pending_free_lock;
+	wait_queue_head_t	pending_free_wq;
+
+	struct work_struct	free_work;
+	/* Thread shutdown wait queue. */
+	wait_queue_head_t	shutdown_wq;
+	struct xen_blkif 	*blkif;
+};
+
 struct xen_blkif {
 	/* Unique identifier for this interface. */
 	domid_t			domid;
 	unsigned int		handle;
-	/* Physical parameters of the comms window. */
-	unsigned int		irq;
 	/* Comms information. */
 	enum blkif_protocol	blk_protocol;
-	union blkif_back_rings	blk_rings;
-	void			*blk_ring;
 	/* The VBD attached to this interface. */
 	struct xen_vbd		vbd;
 	/* Back pointer to the backend_info. */
 	struct backend_info	*be;
-	/* Private fields. */
-	spinlock_t		blk_ring_lock;
 	atomic_t		refcnt;
-
-	wait_queue_head_t	wq;
 	/* for barrier (drain) requests */
 	struct completion	drain_complete;
 	atomic_t		drain;
-	atomic_t		inflight;
-	/* One thread per one blkif. */
-	struct task_struct	*xenblkd;
-	unsigned int		waiting_reqs;
 
 	/* tree to store persistent grants */
+	spinlock_t		pers_gnts_lock;
 	struct rb_root		persistent_gnts;
 	unsigned int		persistent_gnt_c;
 	atomic_t		persistent_gnt_in_use;
@@ -311,12 +327,6 @@ struct xen_blkif {
 	int			free_pages_num;
 	struct list_head	free_pages;
 
-	/* List of all 'pending_req' available */
-	struct list_head	pending_free;
-	/* And its spinlock. */
-	spinlock_t		pending_free_lock;
-	wait_queue_head_t	pending_free_wq;
-
 	/* statistics */
 	unsigned long		st_print;
 	unsigned long long			st_rd_req;
@@ -328,9 +338,9 @@ struct xen_blkif {
 	unsigned long long			st_wr_sect;
 
 	struct work_struct	free_work;
-	/* Thread shutdown wait queue. */
-	wait_queue_head_t	shutdown_wq;
-	unsigned int nr_ring_pages;
+	unsigned int 		nr_ring_pages;
+	/* All rings for this device. */
+	struct xen_blkif_ring 	ring;
 };
 
 struct seg_buf {
@@ -352,7 +362,7 @@ struct grant_page {
  * response queued for it, with the saved 'id' passed back.
  */
 struct pending_req {
-	struct xen_blkif	*blkif;
+	struct xen_blkif_ring   *ring;
 	u64			id;
 	int			nr_segs;
 	atomic_t		pendcnt;
@@ -394,7 +404,7 @@ int xen_blkif_xenbus_init(void);
 irqreturn_t xen_blkif_be_int(int irq, void *dev_id);
 int xen_blkif_schedule(void *arg);
 int xen_blkif_purge_persistent(void *arg);
-void xen_blkbk_free_caches(struct xen_blkif *blkif);
+void xen_blkbk_free_caches(struct xen_blkif_ring *ring);
 
 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
 			      struct backend_info *be, int state);