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

[Matthew Wilcox]

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

Use the xarray spinlock instead of the client spinlock.

Signed-off-by: Matthew Wilcox (Oracle) <wi...@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