block: replace icq->changed with icq->flags

icq->changed was used for ICQ_*_CHANGED bits.  Rename it to flags and
access it under ioc->lock instead of using atomic bitops.
ioc_get_changed() is added so that the changed part can be fetched and
cleared as before.

icq->flags will be used to carry other flags.

Signed-off-by: Tejun Heo <tj@kernel.org>
Tested-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 26 insertions, 4 deletions

diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index 8b782a6..811879c 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -363,13 +363,13 @@ struct io_cq *ioc_create_icq(struct request_queue *q, gfp_t gfp_mask)
 	return icq;
 }
 
-void ioc_set_changed(struct io_context *ioc, int which)
+void ioc_set_icq_flags(struct io_context *ioc, unsigned int flags)
 {
 	struct io_cq *icq;
 	struct hlist_node *n;
 
 	hlist_for_each_entry(icq, n, &ioc->icq_list, ioc_node)
-		set_bit(which, &icq->changed);
+		icq->flags |= flags;
 }
 
 /**
@@ -387,7 +387,7 @@ void ioc_ioprio_changed(struct io_context *ioc, int ioprio)
 
 	spin_lock_irqsave(&ioc->lock, flags);
 	ioc->ioprio = ioprio;
-	ioc_set_changed(ioc, ICQ_IOPRIO_CHANGED);
+	ioc_set_icq_flags(ioc, ICQ_IOPRIO_CHANGED);
 	spin_unlock_irqrestore(&ioc->lock, flags);
 }
 
@@ -404,11 +404,33 @@ void ioc_cgroup_changed(struct io_context *ioc)
 	unsigned long flags;
 
 	spin_lock_irqsave(&ioc->lock, flags);
-	ioc_set_changed(ioc, ICQ_CGROUP_CHANGED);
+	ioc_set_icq_flags(ioc, ICQ_CGROUP_CHANGED);
 	spin_unlock_irqrestore(&ioc->lock, flags);
 }
 EXPORT_SYMBOL(ioc_cgroup_changed);
 
+/**
+ * icq_get_changed - fetch and clear icq changed mask
+ * @icq: icq of interest
+ *
+ * Fetch and clear ICQ_*_CHANGED bits from @icq.  Grabs and releases
+ * @icq->ioc->lock.
+ */
+unsigned icq_get_changed(struct io_cq *icq)
+{
+	unsigned int changed = 0;
+	unsigned long flags;
+
+	if (unlikely(icq->flags & ICQ_CHANGED_MASK)) {
+		spin_lock_irqsave(&icq->ioc->lock, flags);
+		changed = icq->flags & ICQ_CHANGED_MASK;
+		icq->flags &= ~ICQ_CHANGED_MASK;
+		spin_unlock_irqrestore(&icq->ioc->lock, flags);
+	}
+	return changed;
+}
+EXPORT_SYMBOL(icq_get_changed);
+
 static int __init blk_ioc_init(void)
 {
 	iocontext_cachep = kmem_cache_create("blkdev_ioc",