io_uring: store reg buffer end instead of length

It's a bit more convenient for us to store a registered buffer end
address instead of length, see struct io_mapped_ubuf, as it allow to not
recompute it every time.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/39164403fe92f1dc437af134adeec2423cdf9395.1617287883.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 e6508b1..47b02e6 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -194,7 +194,7 @@ enum io_uring_cmd_flags {
 
 struct io_mapped_ubuf {
        u64             ubuf;
-       size_t          len;
+       u64             ubuf_end;
        struct          bio_vec *bvec;
        unsigned int    nr_bvecs;
        unsigned long   acct_pages;
@@ -2797,7 +2797,7 @@ static int io_import_fixed(struct io_kiocb *req, int rw, struct iov_iter *iter)
        if (unlikely(check_add_overflow(buf_addr, (u64)len, &buf_end)))
                return -EFAULT;
        /* not inside the mapped region */
-       if (buf_addr < imu->ubuf || buf_end > imu->ubuf + imu->len)
+       if (unlikely(buf_addr < imu->ubuf || buf_end > imu->ubuf_end))
                return -EFAULT;
 
        /*
@@ -8319,7 +8319,7 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,
        }
        /* store original address for later verification */
        imu->ubuf = ubuf;
-       imu->len = iov->iov_len;
+       imu->ubuf_end = ubuf + iov->iov_len;
        imu->nr_bvecs = nr_pages;
        ret = 0;
 done:
@@ -9378,9 +9378,9 @@ static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m)
        seq_printf(m, "UserBufs:\t%u\n", ctx->nr_user_bufs);
        for (i = 0; has_lock && i < ctx->nr_user_bufs; i++) {
                struct io_mapped_ubuf *buf = &ctx->user_bufs[i];
+               unsigned int len = buf->ubuf_end - buf->ubuf;
 
-               seq_printf(m, "%5u: 0x%llx/%u\n", i, buf->ubuf,
-                                               (unsigned int) buf->len);
+               seq_printf(m, "%5u: 0x%llx/%u\n", i, buf->ubuf, len);
        }
        if (has_lock && !xa_empty(&ctx->personalities)) {
                unsigned long index;