io_uring: deduplicate SCM accounting

Merge io_sqe_file_register() and io_sqe_file_register(). The only
real difference left between them is from where we get an skb.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/dddda3039c71fcbec24b3465cbe8c7e7ae7bb0e8.1649334991.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index f97a0a5..f644c1e 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8601,7 +8601,6 @@ static struct io_sq_data *io_get_sq_data(struct io_uring_params *p,
        return sqd;
 }
 
-#if defined(CONFIG_UNIX)
 /*
  * Ensure the UNIX gc is aware of our file set, so we are certain that
  * the io_uring can be safely unregistered on process exit, even if we have
@@ -8609,38 +8608,59 @@ static struct io_sq_data *io_get_sq_data(struct io_uring_params *p,
  * files because otherwise they can't form a loop and so are not interesting
  * for GC.
  */
-static int __io_sqe_files_scm(struct io_ring_ctx *ctx, struct file *file)
+static int io_sqe_file_register(struct io_ring_ctx *ctx, struct file *file)
 {
+#if defined(CONFIG_UNIX)
        struct sock *sk = ctx->ring_sock->sk;
+       struct sk_buff_head *head = &sk->sk_receive_queue;
        struct scm_fp_list *fpl;
        struct sk_buff *skb;
 
-       fpl = kzalloc(sizeof(*fpl), GFP_KERNEL);
-       if (!fpl)
-               return -ENOMEM;
+       if (likely(!io_file_need_scm(file)))
+               return 0;
+
+       /*
+        * See if we can merge this file into an existing skb SCM_RIGHTS
+        * file set. If there's no room, fall back to allocating a new skb
+        * and filling it in.
+        */
+       spin_lock_irq(&head->lock);
+       skb = skb_peek(head);
+       if (skb && UNIXCB(skb).fp->count < SCM_MAX_FD)
+               __skb_unlink(skb, head);
+       else
+               skb = NULL;
+       spin_unlock_irq(&head->lock);
 
-       skb = alloc_skb(0, GFP_KERNEL);
        if (!skb) {
-               kfree(fpl);
-               return -ENOMEM;
-       }
+               fpl = kzalloc(sizeof(*fpl), GFP_KERNEL);
+               if (!fpl)
+                       return -ENOMEM;
 
-       skb->sk = sk;
+               skb = alloc_skb(0, GFP_KERNEL);
+               if (!skb) {
+                       kfree(fpl);
+                       return -ENOMEM;
+               }
 
-       fpl->user = get_uid(current_user());
-       fpl->fp[0] = get_file(file);
-       unix_inflight(fpl->user, file);
+               fpl->user = get_uid(current_user());
+               fpl->max = SCM_MAX_FD;
+               fpl->count = 0;
 
-       fpl->max = SCM_MAX_FD;
-       fpl->count = 1;
-       UNIXCB(skb).fp = fpl;
-       skb->destructor = unix_destruct_scm;
-       refcount_add(skb->truesize, &sk->sk_wmem_alloc);
-       skb_queue_head(&sk->sk_receive_queue, skb);
+               UNIXCB(skb).fp = fpl;
+               skb->sk = sk;
+               skb->destructor = unix_destruct_scm;
+               refcount_add(skb->truesize, &sk->sk_wmem_alloc);
+       }
+
+       fpl = UNIXCB(skb).fp;
+       fpl->fp[fpl->count++] = get_file(file);
+       unix_inflight(fpl->user, file);
+       skb_queue_head(head, skb);
        fput(file);
+#endif
        return 0;
 }
-#endif
 
 static void io_rsrc_file_put(struct io_ring_ctx *ctx, struct io_rsrc_put *prsrc)
 {
@@ -8760,8 +8780,6 @@ static void io_rsrc_put_work(struct work_struct *work)
        }
 }
 
-static int io_sqe_file_register(struct io_ring_ctx *ctx, struct file *file);
-
 static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
                                 unsigned nr_args, u64 __user *tags)
 {
@@ -8839,51 +8857,6 @@ fail:
        return ret;
 }
 
-static int io_sqe_file_register(struct io_ring_ctx *ctx, struct file *file)
-{
-#if defined(CONFIG_UNIX)
-       struct sock *sock = ctx->ring_sock->sk;
-       struct sk_buff_head *head = &sock->sk_receive_queue;
-       struct sk_buff *skb;
-
-       if (!io_file_need_scm(file))
-               return 0;
-
-       /*
-        * See if we can merge this file into an existing skb SCM_RIGHTS
-        * file set. If there's no room, fall back to allocating a new skb
-        * and filling it in.
-        */
-       spin_lock_irq(&head->lock);
-       skb = skb_peek(head);
-       if (skb) {
-               struct scm_fp_list *fpl = UNIXCB(skb).fp;
-
-               if (fpl->count < SCM_MAX_FD) {
-                       __skb_unlink(skb, head);
-                       spin_unlock_irq(&head->lock);
-                       fpl->fp[fpl->count] = get_file(file);
-                       unix_inflight(fpl->user, fpl->fp[fpl->count]);
-                       fpl->count++;
-                       spin_lock_irq(&head->lock);
-                       __skb_queue_head(head, skb);
-               } else {
-                       skb = NULL;
-               }
-       }
-       spin_unlock_irq(&head->lock);
-
-       if (skb) {
-               fput(file);
-               return 0;
-       }
-
-       return __io_sqe_files_scm(ctx, file);
-#else
-       return 0;
-#endif
-}
-
 static int io_queue_rsrc_removal(struct io_rsrc_data *data, unsigned idx,
                                 struct io_rsrc_node *node, void *rsrc)
 {