ublk: handle UBLK_IO_FETCH_REQ earlier

Check for UBLK_IO_FETCH_REQ early in __ublk_ch_uring_cmd() and skip the
rest of the checks in this case. This allows removing the checks for
NULL io->task and UBLK_IO_FLAG_OWNED_BY_SRV unset in io->flags, which
are only allowed for FETCH.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250620151008.3976463-5-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index cf550a56b19bb2e83b3a8fe67b013473b1af8c67..c2f83036aacf1015c9feabf10027246ae9aa2900 100644 (file)
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -2215,8 +2215,18 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
                goto out;
 
        io = &ubq->ios[tag];
+       /* UBLK_IO_FETCH_REQ can be handled on any task, which sets io->task */
+       if (unlikely(_IOC_NR(cmd_op) == UBLK_IO_FETCH_REQ)) {
+               ret = ublk_fetch(cmd, ubq, io, ub_cmd->addr);
+               if (ret)
+                       goto out;
+
+               ublk_prep_cancel(cmd, issue_flags, ubq, tag);
+               return -EIOCBQUEUED;
+       }
+
        task = READ_ONCE(io->task);
-       if (task && task != current)
+       if (task != current)
                goto out;
 
        /* there is pending io cmd, something must be wrong */
@@ -2225,9 +2235,7 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
                goto out;
        }
 
-       /* only UBLK_IO_FETCH_REQ is allowed if io is not OWNED_BY_SRV */
-       if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV) &&
-           _IOC_NR(cmd_op) != UBLK_IO_FETCH_REQ)
+       if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
                goto out;
 
        /*
@@ -2243,11 +2251,6 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
                return ublk_register_io_buf(cmd, ubq, io, ub_cmd->addr, issue_flags);
        case UBLK_IO_UNREGISTER_IO_BUF:
                return ublk_unregister_io_buf(cmd, ubq, ub_cmd->addr, issue_flags);
-       case UBLK_IO_FETCH_REQ:
-               ret = ublk_fetch(cmd, ubq, io, ub_cmd->addr);
-               if (ret)
-                       goto out;
-               break;
        case UBLK_IO_COMMIT_AND_FETCH_REQ:
                ret = ublk_commit_and_fetch(ubq, io, cmd, ub_cmd, issue_flags);
                if (ret)