[PATCH 19/38] 9p: Convert reqs IDR to XArray

[Matthew Wilcox <willy@infradead.org>]

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

Use the xarray spinlock instead of the client spinlock.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/net/9p/client.h |  2 +-
 net/9p/client.c         | 41 ++++++++++++++++++++---------------------
 2 files changed, 21 insertions(+), 22 deletions(-)

diff --git a/include/net/9p/client.h b/include/net/9p/client.h
index acc60d8a3b3b..6fe36ca0c32e 100644
--- a/include/net/9p/client.h
+++ b/include/net/9p/client.h
@@ -124,7 +124,7 @@ struct p9_client {
 	} trans_opts;
 
 	struct idr fids;
-	struct idr reqs;
+	struct xarray reqs;
 
 	char name[__NEW_UTS_LEN + 1];
 };
diff --git a/net/9p/client.c b/net/9p/client.c
index 9622f3e469f6..5c566e48f63e 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -269,7 +269,8 @@ p9_tag_alloc(struct p9_client *c, int8_t type, unsigned int max_size)
 {
 	struct p9_req_t *req = kmem_cache_alloc(p9_req_cache, GFP_NOFS);
 	int alloc_msize = min(c->msize, max_size);
-	int tag;
+	int err;
+	u32 tag;
 
 	if (!req)
 		return ERR_PTR(-ENOMEM);
@@ -285,17 +286,17 @@ p9_tag_alloc(struct p9_client *c, int8_t type, unsigned int max_size)
 	init_waitqueue_head(&req->wq);
 	INIT_LIST_HEAD(&req->req_list);
 
-	idr_preload(GFP_NOFS);
-	spin_lock_irq(&c->lock);
-	if (type == P9_TVERSION)
-		tag = idr_alloc(&c->reqs, req, P9_NOTAG, P9_NOTAG + 1,
-				GFP_NOWAIT);
-	else
-		tag = idr_alloc(&c->reqs, req, 0, P9_NOTAG, GFP_NOWAIT);
+	xa_lock_irq(&c->reqs);
+	if (type == P9_TVERSION) {
+		tag = P9_NOTAG;
+		err = __xa_insert(&c->reqs, P9_NOTAG, req, GFP_NOFS);
+	} else {
+		err = __xa_alloc(&c->reqs, &tag, req, XA_LIMIT(0, P9_NOTAG - 1),
+				GFP_NOFS);
+	}
 	req->tc.tag = tag;
-	spin_unlock_irq(&c->lock);
-	idr_preload_end();
-	if (tag < 0)
+	xa_unlock_irq(&c->reqs);
+	if (err < 0)
 		goto free;
 
 	/* Init ref to two because in the general case there is one ref
@@ -334,7 +335,7 @@ struct p9_req_t *p9_tag_lookup(struct p9_client *c, u16 tag)
 
 	rcu_read_lock();
 again:
-	req = idr_find(&c->reqs, tag);
+	req = xa_load(&c->reqs, tag);
 	if (req) {
 		/* We have to be careful with the req found under rcu_read_lock
 		 * Thanks to SLAB_TYPESAFE_BY_RCU we can safely try to get the
@@ -367,9 +368,9 @@ static int p9_tag_remove(struct p9_client *c, struct p9_req_t *r)
 	u16 tag = r->tc.tag;
 
 	p9_debug(P9_DEBUG_MUX, "clnt %p req %p tag: %d\n", c, r, tag);
-	spin_lock_irqsave(&c->lock, flags);
-	idr_remove(&c->reqs, tag);
-	spin_unlock_irqrestore(&c->lock, flags);
+	xa_lock_irqsave(&c->reqs, flags);
+	__xa_erase(&c->reqs, tag);
+	xa_unlock_irqrestore(&c->reqs, flags);
 	return p9_req_put(r);
 }
 
@@ -397,16 +398,14 @@ EXPORT_SYMBOL(p9_req_put);
 static void p9_tag_cleanup(struct p9_client *c)
 {
 	struct p9_req_t *req;
-	int id;
+	unsigned long id;
 
-	rcu_read_lock();
-	idr_for_each_entry(&c->reqs, req, id) {
-		pr_info("Tag %d still in use\n", id);
+	xa_for_each(&c->reqs, id, req) {
+		pr_info("Tag %ld still in use\n", id);
 		if (p9_tag_remove(c, req) == 0)
 			pr_warn("Packet with tag %d has still references",
 				req->tc.tag);
 	}
-	rcu_read_unlock();
 }
 
 /**
@@ -1016,7 +1015,7 @@ struct p9_client *p9_client_create(const char *dev_name, char *options)
 
 	spin_lock_init(&clnt->lock);
 	idr_init(&clnt->fids);
-	idr_init(&clnt->reqs);
+	xa_init_flags(&clnt->reqs, XA_FLAGS_ALLOC | XA_FLAGS_LOCK_IRQ);
 
 	err = parse_opts(options, clnt);
 	if (err < 0)
-- 
2.23.0.rc1