From: Matthew Wilcox <mawil...@microsoft.com>

Skip converting the lock to use xa_lock; I think this code can live with
the double-locking.

Signed-off-by: Matthew Wilcox <mawil...@microsoft.com>
---
 block/blk-ioc.c           | 13 +++++++------
 include/linux/iocontext.h |  6 +++---
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index f23311e4b201..baf83c8ac503 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -68,7 +68,7 @@ static void ioc_destroy_icq(struct io_cq *icq)
 
        lockdep_assert_held(&ioc->lock);
 
-       radix_tree_delete(&ioc->icq_tree, icq->q->id);
+       xa_erase(&ioc->icq_array, icq->q->id);
        hlist_del_init(&icq->ioc_node);
        list_del_init(&icq->q_node);
 
@@ -278,7 +278,7 @@ int create_task_io_context(struct task_struct *task, gfp_t 
gfp_flags, int node)
        atomic_set(&ioc->nr_tasks, 1);
        atomic_set(&ioc->active_ref, 1);
        spin_lock_init(&ioc->lock);
-       INIT_RADIX_TREE(&ioc->icq_tree, GFP_ATOMIC | __GFP_HIGH);
+       xa_init_flags(&ioc->icq_array, XA_FLAGS_LOCK_IRQ);
        INIT_HLIST_HEAD(&ioc->icq_list);
        INIT_WORK(&ioc->release_work, ioc_release_fn);
 
@@ -363,7 +363,7 @@ struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct 
request_queue *q)
        if (icq && icq->q == q)
                goto out;
 
-       icq = radix_tree_lookup(&ioc->icq_tree, q->id);
+       icq = xa_load(&ioc->icq_array, q->id);
        if (icq && icq->q == q)
                rcu_assign_pointer(ioc->icq_hint, icq); /* allowed to race */
        else
@@ -398,7 +398,7 @@ struct io_cq *ioc_create_icq(struct io_context *ioc, struct 
request_queue *q,
        if (!icq)
                return NULL;
 
-       if (radix_tree_maybe_preload(gfp_mask) < 0) {
+       if (xa_reserve(&ioc->icq_array, q->id, gfp_mask)) {
                kmem_cache_free(et->icq_cache, icq);
                return NULL;
        }
@@ -412,7 +412,8 @@ struct io_cq *ioc_create_icq(struct io_context *ioc, struct 
request_queue *q,
        spin_lock_irq(q->queue_lock);
        spin_lock(&ioc->lock);
 
-       if (likely(!radix_tree_insert(&ioc->icq_tree, q->id, icq))) {
+       if (likely(!xa_store(&ioc->icq_array, q->id, icq,
+                                               GFP_ATOMIC | __GFP_HIGH))) {
                hlist_add_head(&icq->ioc_node, &ioc->icq_list);
                list_add(&icq->q_node, &q->icq_list);
                if (et->uses_mq && et->ops.mq.init_icq)
@@ -421,6 +422,7 @@ struct io_cq *ioc_create_icq(struct io_context *ioc, struct 
request_queue *q,
                        et->ops.sq.elevator_init_icq_fn(icq);
        } else {
                kmem_cache_free(et->icq_cache, icq);
+               xa_erase(&ioc->icq_array, q->id);
                icq = ioc_lookup_icq(ioc, q);
                if (!icq)
                        printk(KERN_ERR "cfq: icq link failed!\n");
@@ -428,7 +430,6 @@ struct io_cq *ioc_create_icq(struct io_context *ioc, struct 
request_queue *q,
 
        spin_unlock(&ioc->lock);
        spin_unlock_irq(q->queue_lock);
-       radix_tree_preload_end();
        return icq;
 }
 
diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h
index dba15ca8e60b..e16224f70084 100644
--- a/include/linux/iocontext.h
+++ b/include/linux/iocontext.h
@@ -2,9 +2,9 @@
 #ifndef IOCONTEXT_H
 #define IOCONTEXT_H
 
-#include <linux/radix-tree.h>
 #include <linux/rcupdate.h>
 #include <linux/workqueue.h>
+#include <linux/xarray.h>
 
 enum {
        ICQ_EXITED              = 1 << 2,
@@ -56,7 +56,7 @@ enum {
  * - ioc->icq_list and icq->ioc_node are protected by ioc lock.
  *   q->icq_list and icq->q_node by q lock.
  *
- * - ioc->icq_tree and ioc->icq_hint are protected by ioc lock, while icq
+ * - ioc->icq_array and ioc->icq_hint are protected by ioc lock, while icq
  *   itself is protected by q lock.  However, both the indexes and icq
  *   itself are also RCU managed and lookup can be performed holding only
  *   the q lock.
@@ -111,7 +111,7 @@ struct io_context {
        int nr_batch_requests;     /* Number of requests left in the batch */
        unsigned long last_waited; /* Time last woken after wait for request */
 
-       struct radix_tree_root  icq_tree;
+       struct xarray           icq_array;
        struct io_cq __rcu      *icq_hint;
        struct hlist_head       icq_list;
 
-- 
2.15.1

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