io_uring: cleanup buffer register

In preparation for more changes do a little cleanup of
io_sqe_buffers_register(). Move all args/invariant checking into it from
io_buffers_map_alloc(), because it's confusing. And add a bit more
cleaning for the loop.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/93292cb9708c8455e5070cc855861d94e11ca042.1618101759.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 e9a2f8f39eb32c3ec63bce820288ff3aadae8e65..76c8bd6a25d1e8e4eb1000216e8adc7bc4b7e660 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8306,17 +8306,8 @@ done:
 
 static int io_buffers_map_alloc(struct io_ring_ctx *ctx, unsigned int nr_args)
 {
-       if (ctx->user_bufs)
-               return -EBUSY;
-       if (!nr_args || nr_args > UIO_MAXIOV)
-               return -EINVAL;
-
-       ctx->user_bufs = kcalloc(nr_args, sizeof(struct io_mapped_ubuf),
-                                       GFP_KERNEL);
-       if (!ctx->user_bufs)
-               return -ENOMEM;
-
-       return 0;
+       ctx->user_bufs = kcalloc(nr_args, sizeof(*ctx->user_bufs), GFP_KERNEL);
+       return ctx->user_bufs ? 0 : -ENOMEM;
 }
 
 static int io_buffer_validate(struct iovec *iov)
@@ -8348,26 +8339,26 @@ static int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
        struct iovec iov;
        struct page *last_hpage = NULL;
 
+       if (ctx->user_bufs)
+               return -EBUSY;
+       if (!nr_args || nr_args > UIO_MAXIOV)
+               return -EINVAL;
        ret = io_buffers_map_alloc(ctx, nr_args);
        if (ret)
                return ret;
 
-       for (i = 0; i < nr_args; i++) {
+       for (i = 0; i < nr_args; i++, ctx->nr_user_bufs++) {
                struct io_mapped_ubuf *imu = &ctx->user_bufs[i];
 
                ret = io_copy_iov(ctx, &iov, arg, i);
                if (ret)
                        break;
-
                ret = io_buffer_validate(&iov);
                if (ret)
                        break;
-
                ret = io_sqe_buffer_register(ctx, &iov, imu, &last_hpage);
                if (ret)
                        break;
-
-               ctx->nr_user_bufs++;
        }
 
        if (ret)