ublk: add `union ublk_io_buf` with improved naming

Add `union ublk_io_buf` for naming the anonymous union of struct ublk_io's
addr and buf fields, meantime apply it to `struct ublk_io` for storing either
ublk auto buffer register data or ublk server io buffer address.

The union uses clear field names:
- `addr`: for regular ublk server io buffer addresses
- `auto_reg`: for ublk auto buffer registration data

This eliminates confusing access patterns and improves code readability.

Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 7e0f1f481a3a297716dd5a1a4e679e933b730b9c..7217146781fa3556c0faf841e2b8698e794fd4d0 100644 (file)
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -155,12 +155,13 @@ struct ublk_uring_cmd_pdu {
  */
 #define UBLK_REFCOUNT_INIT (REFCOUNT_MAX / 2)
 
+union ublk_io_buf {
+       __u64   addr;
+       struct ublk_auto_buf_reg auto_reg;
+};
+
 struct ublk_io {
-       /* userspace buffer address from io cmd */
-       union {
-               __u64   addr;
-               struct ublk_auto_buf_reg buf;
-       };
+       union ublk_io_buf buf;
        unsigned int flags;
        int res;
 
@@ -498,7 +499,7 @@ static blk_status_t ublk_setup_iod_zoned(struct ublk_queue *ubq,
        iod->op_flags = ublk_op | ublk_req_build_flags(req);
        iod->nr_sectors = blk_rq_sectors(req);
        iod->start_sector = blk_rq_pos(req);
-       iod->addr = io->addr;
+       iod->addr = io->buf.addr;
 
        return BLK_STS_OK;
 }
@@ -981,7 +982,7 @@ static unsigned int ublk_map_io(const struct ublk_queue *ubq,
                struct iov_iter iter;
                const int dir = ITER_DEST;
 
-               import_ubuf(dir, u64_to_user_ptr(io->addr), rq_bytes, &iter);
+               import_ubuf(dir, u64_to_user_ptr(io->buf.addr), rq_bytes, &iter);
                return ublk_copy_user_pages(req, 0, &iter, dir);
        }
        return rq_bytes;
@@ -1002,7 +1003,7 @@ static unsigned int ublk_unmap_io(bool need_map,
 
                WARN_ON_ONCE(io->res > rq_bytes);
 
-               import_ubuf(dir, u64_to_user_ptr(io->addr), io->res, &iter);
+               import_ubuf(dir, u64_to_user_ptr(io->buf.addr), io->res, &iter);
                return ublk_copy_user_pages(req, 0, &iter, dir);
        }
        return rq_bytes;
@@ -1068,7 +1069,7 @@ static blk_status_t ublk_setup_iod(struct ublk_queue *ubq, struct request *req)
        iod->op_flags = ublk_op | ublk_req_build_flags(req);
        iod->nr_sectors = blk_rq_sectors(req);
        iod->start_sector = blk_rq_pos(req);
-       iod->addr = io->addr;
+       iod->addr = io->buf.addr;
 
        return BLK_STS_OK;
 }
@@ -1182,9 +1183,9 @@ static bool ublk_auto_buf_reg(const struct ublk_queue *ubq, struct request *req,
        int ret;
 
        ret = io_buffer_register_bvec(cmd, req, ublk_io_release,
-                                     io->buf.index, issue_flags);
+                                     io->buf.auto_reg.index, issue_flags);
        if (ret) {
-               if (io->buf.flags & UBLK_AUTO_BUF_REG_FALLBACK) {
+               if (io->buf.auto_reg.flags & UBLK_AUTO_BUF_REG_FALLBACK) {
                        ublk_auto_buf_reg_fallback(ubq, io);
                        return true;
                }
@@ -1473,7 +1474,7 @@ static void ublk_queue_reinit(struct ublk_device *ub, struct ublk_queue *ubq)
                 */
                io->flags &= UBLK_IO_FLAG_CANCELED;
                io->cmd = NULL;
-               io->addr = 0;
+               io->buf.addr = 0;
 
                /*
                 * old task is PF_EXITING, put it now
@@ -2034,13 +2035,16 @@ static inline int ublk_check_cmd_op(u32 cmd_op)
 
 static inline int ublk_set_auto_buf_reg(struct ublk_io *io, struct io_uring_cmd *cmd)
 {
-       io->buf = ublk_sqe_addr_to_auto_buf_reg(READ_ONCE(cmd->sqe->addr));
+       struct ublk_auto_buf_reg buf;
+
+       buf = ublk_sqe_addr_to_auto_buf_reg(READ_ONCE(cmd->sqe->addr));
 
-       if (io->buf.reserved0 || io->buf.reserved1)
+       if (buf.reserved0 || buf.reserved1)
                return -EINVAL;
 
-       if (io->buf.flags & ~UBLK_AUTO_BUF_REG_F_MASK)
+       if (buf.flags & ~UBLK_AUTO_BUF_REG_F_MASK)
                return -EINVAL;
+       io->buf.auto_reg = buf;
        return 0;
 }
 
@@ -2062,7 +2066,7 @@ static int ublk_handle_auto_buf_reg(struct ublk_io *io,
                 * this ublk request gets stuck.
                 */
                if (io->buf_ctx_handle == io_uring_cmd_ctx_handle(cmd))
-                       *buf_idx = io->buf.index;
+                       *buf_idx = io->buf.auto_reg.index;
        }
 
        return ublk_set_auto_buf_reg(io, cmd);
@@ -2090,7 +2094,7 @@ ublk_config_io_buf(const struct ublk_device *ub, struct ublk_io *io,
        if (ublk_dev_support_auto_buf_reg(ub))
                return ublk_handle_auto_buf_reg(io, cmd, buf_idx);
 
-       io->addr = buf_addr;
+       io->buf.addr = buf_addr;
        return 0;
 }
 
@@ -2287,7 +2291,7 @@ static bool ublk_get_data(const struct ublk_queue *ubq, struct ublk_io *io,
         */
        io->flags &= ~UBLK_IO_FLAG_NEED_GET_DATA;
        /* update iod->addr because ublksrv may have passed a new io buffer */
-       ublk_get_iod(ubq, req->tag)->addr = io->addr;
+       ublk_get_iod(ubq, req->tag)->addr = io->buf.addr;
        pr_devel("%s: update iod->addr: qid %d tag %d io_flags %x addr %llx\n",
                        __func__, ubq->q_id, req->tag, io->flags,
                        ublk_get_iod(ubq, req->tag)->addr);