nvme/scsi: don't rely on BLK_MAX_CDB

The NVMe SCSI emulation doesn't use BLOCK_PC requests, so BLK_MAX_CDB
doesn't have a meaning for it.  Instead opencode the value of 16
and refactor the code a bit so that related checks are next to each
other and we only need to use the value in one place.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/drivers/nvme/host/scsi.c b/drivers/nvme/host/scsi.c
index 0f0fcea..f49ae27 100644 (file)
--- a/drivers/nvme/host/scsi.c
+++ b/drivers/nvme/host/scsi.c
@@ -2348,12 +2348,14 @@ static int nvme_trans_unmap(struct nvme_ns *ns, struct sg_io_hdr *hdr,
 
 static int nvme_scsi_translate(struct nvme_ns *ns, struct sg_io_hdr *hdr)
 {
-       u8 cmd[BLK_MAX_CDB];
+       u8 cmd[16];
        int retcode;
        unsigned int opcode;
 
        if (hdr->cmdp == NULL)
                return -EMSGSIZE;
+       if (hdr->cmd_len > sizeof(cmd))
+               return -EINVAL;
        if (copy_from_user(cmd, hdr->cmdp, hdr->cmd_len))
                return -EFAULT;
 
@@ -2452,8 +2454,6 @@ int nvme_sg_io(struct nvme_ns *ns, struct sg_io_hdr __user *u_hdr)
                return -EFAULT;
        if (hdr.interface_id != 'S')
                return -EINVAL;
-       if (hdr.cmd_len > BLK_MAX_CDB)
-               return -EINVAL;
 
        /*
         * A positive return code means a NVMe status, which has been