ublk: move auto buffer register handling into one dedicated helper

Move check & clearing UBLK_IO_FLAG_AUTO_BUF_REG to
ublk_handle_auto_buf_reg(), also return buffer index from this helper.

Also move ublk_set_auto_buf_reg() to this single helper too.

Add ublk_config_io_buf() for setting up ublk io buffer, covers both
ublk buffer copy or auto buffer register.

Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250713143415.2857561-7-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 62393c64f17d3f1b686988dd7b4e473a6bcb038d..f70fab36fbc78d60c30975f4aa7a3e8c553cee09 100644 (file)
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -48,6 +48,8 @@
 
 #define UBLK_MINORS            (1U << MINORBITS)
 
+#define UBLK_INVALID_BUF_IDX   ((u16)-1)
+
 /* private ioctl command mirror */
 #define UBLK_CMD_DEL_DEV_ASYNC _IOC_NR(UBLK_U_CMD_DEL_DEV_ASYNC)
 #define UBLK_CMD_UPDATE_SIZE   _IOC_NR(UBLK_U_CMD_UPDATE_SIZE)
@@ -2009,10 +2011,47 @@ static inline int ublk_check_cmd_op(u32 cmd_op)
        return 0;
 }
 
+static inline int ublk_set_auto_buf_reg(struct io_uring_cmd *cmd)
+{
+       struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
+
+       pdu->buf = ublk_sqe_addr_to_auto_buf_reg(READ_ONCE(cmd->sqe->addr));
+
+       if (pdu->buf.reserved0 || pdu->buf.reserved1)
+               return -EINVAL;
+
+       if (pdu->buf.flags & ~UBLK_AUTO_BUF_REG_F_MASK)
+               return -EINVAL;
+       return 0;
+}
+
+static int ublk_handle_auto_buf_reg(struct ublk_io *io,
+                                   struct io_uring_cmd *cmd,
+                                   u16 *buf_idx)
+{
+       if (io->flags & UBLK_IO_FLAG_AUTO_BUF_REG) {
+               io->flags &= ~UBLK_IO_FLAG_AUTO_BUF_REG;
+
+               /*
+                * `UBLK_F_AUTO_BUF_REG` only works iff `UBLK_IO_FETCH_REQ`
+                * and `UBLK_IO_COMMIT_AND_FETCH_REQ` are issued from same
+                * `io_ring_ctx`.
+                *
+                * If this uring_cmd's io_ring_ctx isn't same with the
+                * one for registering the buffer, it is ublk server's
+                * responsibility for unregistering the buffer, otherwise
+                * this ublk request gets stuck.
+                */
+               if (io->buf_ctx_handle == io_uring_cmd_ctx_handle(cmd))
+                       *buf_idx = io->buf_index;
+       }
+
+       return ublk_set_auto_buf_reg(cmd);
+}
+
 /* Once we return, `io->req` can't be used any more */
 static inline struct request *
-ublk_fill_io_cmd(struct ublk_io *io, struct io_uring_cmd *cmd,
-                unsigned long buf_addr)
+ublk_fill_io_cmd(struct ublk_io *io, struct io_uring_cmd *cmd)
 {
        struct request *req = io->req;
 
@@ -2020,11 +2059,22 @@ ublk_fill_io_cmd(struct ublk_io *io, struct io_uring_cmd *cmd,
        io->flags |= UBLK_IO_FLAG_ACTIVE;
        /* now this cmd slot is owned by ublk driver */
        io->flags &= ~UBLK_IO_FLAG_OWNED_BY_SRV;
-       io->addr = buf_addr;
 
        return req;
 }
 
+static inline int
+ublk_config_io_buf(const struct ublk_queue *ubq, struct ublk_io *io,
+                  struct io_uring_cmd *cmd, unsigned long buf_addr,
+                  u16 *buf_idx)
+{
+       if (ublk_support_auto_buf_reg(ubq))
+               return ublk_handle_auto_buf_reg(io, cmd, buf_idx);
+
+       io->addr = buf_addr;
+       return 0;
+}
+
 static inline void ublk_prep_cancel(struct io_uring_cmd *cmd,
                                    unsigned int issue_flags,
                                    struct ublk_queue *ubq, unsigned int tag)
@@ -2040,20 +2090,6 @@ static inline void ublk_prep_cancel(struct io_uring_cmd *cmd,
        io_uring_cmd_mark_cancelable(cmd, issue_flags);
 }
 
-static inline int ublk_set_auto_buf_reg(struct io_uring_cmd *cmd)
-{
-       struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
-
-       pdu->buf = ublk_sqe_addr_to_auto_buf_reg(READ_ONCE(cmd->sqe->addr));
-
-       if (pdu->buf.reserved0 || pdu->buf.reserved1)
-               return -EINVAL;
-
-       if (pdu->buf.flags & ~UBLK_AUTO_BUF_REG_F_MASK)
-               return -EINVAL;
-       return 0;
-}
-
 static void ublk_io_release(void *priv)
 {
        struct request *rq = priv;
@@ -2174,13 +2210,11 @@ static int ublk_fetch(struct io_uring_cmd *cmd, struct ublk_queue *ubq,
                goto out;
        }
 
-       if (ublk_support_auto_buf_reg(ubq)) {
-               ret = ublk_set_auto_buf_reg(cmd);
-               if (ret)
-                       goto out;
-       }
+       ublk_fill_io_cmd(io, cmd);
+       ret = ublk_config_io_buf(ubq, io, cmd, buf_addr, NULL);
+       if (ret)
+               goto out;
 
-       ublk_fill_io_cmd(io, cmd, buf_addr);
        WRITE_ONCE(io->task, get_task_struct(current));
        ublk_mark_io_ready(ub, ubq);
 out:
@@ -2212,35 +2246,13 @@ static int ublk_check_commit_and_fetch(const struct ublk_queue *ubq,
        return 0;
 }
 
-static int ublk_commit_and_fetch(const struct ublk_queue *ubq,
-                                struct ublk_io *io, struct io_uring_cmd *cmd,
-                                struct request *req, unsigned int issue_flags,
-                                __u64 zone_append_lba)
+static void ublk_commit_and_fetch(const struct ublk_queue *ubq,
+                                 struct ublk_io *io, struct io_uring_cmd *cmd,
+                                 struct request *req, unsigned int issue_flags,
+                                 __u64 zone_append_lba, u16 buf_idx)
 {
-       if (ublk_support_auto_buf_reg(ubq)) {
-               int ret;
-
-               /*
-                * `UBLK_F_AUTO_BUF_REG` only works iff `UBLK_IO_FETCH_REQ`
-                * and `UBLK_IO_COMMIT_AND_FETCH_REQ` are issued from same
-                * `io_ring_ctx`.
-                *
-                * If this uring_cmd's io_ring_ctx isn't same with the
-                * one for registering the buffer, it is ublk server's
-                * responsibility for unregistering the buffer, otherwise
-                * this ublk request gets stuck.
-                */
-               if (io->flags & UBLK_IO_FLAG_AUTO_BUF_REG) {
-                       if (io->buf_ctx_handle == io_uring_cmd_ctx_handle(cmd))
-                               io_buffer_unregister_bvec(cmd, io->buf_index,
-                                               issue_flags);
-                       io->flags &= ~UBLK_IO_FLAG_AUTO_BUF_REG;
-               }
-
-               ret = ublk_set_auto_buf_reg(cmd);
-               if (ret)
-                       return ret;
-       }
+       if (buf_idx != UBLK_INVALID_BUF_IDX)
+               io_buffer_unregister_bvec(cmd, buf_idx, issue_flags);
 
        if (req_op(req) == REQ_OP_ZONE_APPEND)
                req->__sector = zone_append_lba;
@@ -2249,7 +2261,6 @@ static int ublk_commit_and_fetch(const struct ublk_queue *ubq,
                ublk_sub_req_ref(io, req);
        else
                __ublk_complete_rq(req);
-       return 0;
 }
 
 static bool ublk_get_data(const struct ublk_queue *ubq, struct ublk_io *io,
@@ -2274,6 +2285,7 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
                               unsigned int issue_flags,
                               const struct ublksrv_io_cmd *ub_cmd)
 {
+       u16 buf_idx = UBLK_INVALID_BUF_IDX;
        struct ublk_device *ub = cmd->file->private_data;
        struct ublk_queue *ubq;
        struct ublk_io *io;
@@ -2353,9 +2365,10 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
                if (ret)
                        goto out;
                io->res = ub_cmd->result;
-               req = ublk_fill_io_cmd(io, cmd, ub_cmd->addr);
-               ret = ublk_commit_and_fetch(ubq, io, cmd, req, issue_flags,
-                                           ub_cmd->zone_append_lba);
+               req = ublk_fill_io_cmd(io, cmd);
+               ret = ublk_config_io_buf(ubq, io, cmd, ub_cmd->addr, &buf_idx);
+               ublk_commit_and_fetch(ubq, io, cmd, req, issue_flags,
+                                     ub_cmd->zone_append_lba, buf_idx);
                if (ret)
                        goto out;
                break;
@@ -2365,7 +2378,9 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
                 * uring_cmd active first and prepare for handling new requeued
                 * request
                 */
-               req = ublk_fill_io_cmd(io, cmd, ub_cmd->addr);
+               req = ublk_fill_io_cmd(io, cmd);
+               ret = ublk_config_io_buf(ubq, io, cmd, ub_cmd->addr, NULL);
+               WARN_ON_ONCE(ret);
                if (likely(ublk_get_data(ubq, io, req))) {
                        __ublk_prep_compl_io_cmd(io, req);
                        return UBLK_IO_RES_OK;