io_uring: use kiocb->private to hold rw_len

We don't need a separate member in io_rw for this, we can just use the
kiocb->private field as we're not using it for anything else anyway.
This saves 8 bytes in io_rw, which we'll be needing once kiocb grows
a new member.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 1d94a434b3489b22deb167d36874ea07a4db9a5b..9b2a47c8df3afb5762d673fa4c03b878e36eb28d 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -561,7 +561,6 @@ struct io_rw {
        /* NOTE: kiocb has the file as the first member, so don't do it here */
        struct kiocb                    kiocb;
        u64                             addr;
-       u64                             len;
 };
 
 struct io_connect {
@@ -2704,6 +2703,16 @@ static void io_mark_alloc_cache(struct kiocb *kiocb)
 #endif /* CONFIG_BLOCK */
 }
 
+static inline void *u64_to_ptr(__u64 ptr)
+{
+       return (void *)(unsigned long) ptr;
+}
+
+static inline __u64 ptr_to_u64(void *ptr)
+{
+       return (__u64)(unsigned long)ptr;
+}
+
 static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
        struct io_ring_ctx *ctx = req->ctx;
@@ -2762,7 +2771,7 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe)
        }
 
        req->rw.addr = READ_ONCE(sqe->addr);
-       req->rw.len = READ_ONCE(sqe->len);
+       req->rw.kiocb.private = u64_to_ptr(READ_ONCE(sqe->len));
        req->buf_index = READ_ONCE(sqe->buf_index);
        return 0;
 }
@@ -2831,7 +2840,7 @@ static void kiocb_done(struct kiocb *kiocb, ssize_t ret,
 static int __io_import_fixed(struct io_kiocb *req, int rw, struct iov_iter *iter,
                             struct io_mapped_ubuf *imu)
 {
-       size_t len = req->rw.len;
+       size_t len = ptr_to_u64(req->rw.kiocb.private);
        u64 buf_end, buf_addr = req->rw.addr;
        size_t offset;
 
@@ -3029,7 +3038,7 @@ static ssize_t io_iov_buffer_select(struct io_kiocb *req, struct iovec *iov,
                iov[0].iov_len = kbuf->len;
                return 0;
        }
-       if (req->rw.len != 1)
+       if (ptr_to_u64(req->rw.kiocb.private) != 1)
                return -EINVAL;
 
 #ifdef CONFIG_COMPAT
@@ -3044,7 +3053,7 @@ static int io_import_iovec(int rw, struct io_kiocb *req, struct iovec **iovec,
                           struct iov_iter *iter, bool needs_lock)
 {
        void __user *buf = u64_to_user_ptr(req->rw.addr);
-       size_t sqe_len = req->rw.len;
+       size_t sqe_len = ptr_to_u64(req->rw.kiocb.private);
        u8 opcode = req->opcode;
        ssize_t ret;
 
@@ -3062,7 +3071,7 @@ static int io_import_iovec(int rw, struct io_kiocb *req, struct iovec **iovec,
                        buf = io_rw_buffer_select(req, &sqe_len, needs_lock);
                        if (IS_ERR(buf))
                                return PTR_ERR(buf);
-                       req->rw.len = sqe_len;
+                       req->rw.kiocb.private = u64_to_ptr(sqe_len);
                }
 
                ret = import_single_range(rw, buf, sqe_len, *iovec, iter);
@@ -3095,6 +3104,7 @@ static ssize_t loop_rw_iter(int rw, struct io_kiocb *req, struct iov_iter *iter)
 {
        struct kiocb *kiocb = &req->rw.kiocb;
        struct file *file = req->file;
+       unsigned long rw_len;
        ssize_t ret = 0;
 
        /*
@@ -3107,6 +3117,7 @@ static ssize_t loop_rw_iter(int rw, struct io_kiocb *req, struct iov_iter *iter)
        if (kiocb->ki_flags & IOCB_NOWAIT)
                return -EAGAIN;
 
+       rw_len = ptr_to_u64(req->rw.kiocb.private);
        while (iov_iter_count(iter)) {
                struct iovec iovec;
                ssize_t nr;
@@ -3115,7 +3126,7 @@ static ssize_t loop_rw_iter(int rw, struct io_kiocb *req, struct iov_iter *iter)
                        iovec = iov_iter_iovec(iter);
                } else {
                        iovec.iov_base = u64_to_user_ptr(req->rw.addr);
-                       iovec.iov_len = req->rw.len;
+                       iovec.iov_len = rw_len;
                }
 
                if (rw == READ) {
@@ -3134,7 +3145,7 @@ static ssize_t loop_rw_iter(int rw, struct io_kiocb *req, struct iov_iter *iter)
                ret += nr;
                if (nr != iovec.iov_len)
                        break;
-               req->rw.len -= nr;
+               rw_len -= nr;
                req->rw.addr += nr;
                iov_iter_advance(iter, nr);
        }