From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 62730280CFC for ; Mon, 9 Jun 2025 07:34:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749454487; cv=none; b=kQimWuP3MHDufbP+M6DIrxBik4l0mNz+zp+oyF9RQA1RNSYMJvl82VvJ//zLs38jNWUYS0+CYbof8nVOTgDkhs9DrZ4i9C0Iv/5LdEiOIlobtVY89P/eJONwFcyOLF2bO2o67ZqJNjPAjUP+31NmrbbtyxP4aAlKCQDelG9c10U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749454487; c=relaxed/simple; bh=rMwG/VF1pIUbgJklj0TXzQCNW5kFzd+4LioRCQBma/Y=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JJTJZgUBLHwNVmvd1CdJDPNFY6fBsNeNNCF3ovAi4vrmczxrOR2YvRhaVPS/aHD0yHwg5QW26/NE023T/pBelMwTSuZ4QMQqoAFw+sP6XRn6Q3n70LUtOU+U3uosO97mPu7fBeUYv0XIzmIsS61hJvY+S/S5VACtq52z17wVpng= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=c4U43pUU; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="c4U43pUU" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1749454483; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=DY8MSc65FVK3o9QuSU57y41EYwt0GBkJUnP3i1gOZJ8=; b=c4U43pUUvHIjyez8GFc3uv4nzxGmsoxvbeO7MZV4Fuk1LeamDlj7oMDKdYjKzZ6GsDHzAc ZTruMyd+omxViRlyTMltcBU3tARum96D2LFXpir8X1henDqsKucNPc8XeCnWIwdVDy6EjS aGGNOomDjKouzlZy0wBPDTGI3kgmspM= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-528-K88MKwqOOMCZOXFE86MJYA-1; Mon, 09 Jun 2025 03:34:40 -0400 X-MC-Unique: K88MKwqOOMCZOXFE86MJYA-1 X-Mimecast-MFC-AGG-ID: K88MKwqOOMCZOXFE86MJYA_1749454479 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 126FC195608C; Mon, 9 Jun 2025 07:34:39 +0000 (UTC) Received: from fedora (unknown [10.72.116.58]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 61315195608D; Mon, 9 Jun 2025 07:34:35 +0000 (UTC) Date: Mon, 9 Jun 2025 15:34:31 +0800 From: Ming Lei To: Caleb Sander Mateos Cc: Uday Shankar , linux-block@vger.kernel.org Subject: Re: [PATCH 6/8] ublk: allow UBLK_IO_(UN)REGISTER_IO_BUF on any task Message-ID: References: <20250606214011.2576398-1-csander@purestorage.com> <20250606214011.2576398-7-csander@purestorage.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250606214011.2576398-7-csander@purestorage.com> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 On Fri, Jun 06, 2025 at 03:40:09PM -0600, Caleb Sander Mateos wrote: > Currently, UBLK_IO_REGISTER_IO_BUF and UBLK_IO_UNREGISTER_IO_BUF are > only permitted on the ublk_io's daemon task. But this restriction is > unnecessary. ublk_register_io_buf() calls __ublk_check_and_get_req() to > look up the request from the tagset and atomically take a reference on > the request without accessing the ublk_io. ublk_unregister_io_buf() > doesn't use the q_id or tag at all. > > So allow these opcodes even on tasks other than io->task. > > Handle UBLK_IO_UNREGISTER_IO_BUF before obtaining the ubq and io since > the buffer index being unregistered is not necessarily related to the > specified q_id and tag. > > Add a feature flag UBLK_F_BUF_REG_OFF_DAEMON that userspace can use to > determine whether the kernel supports off-daemon buffer registration. > > Suggested-by: Ming Lei > Signed-off-by: Caleb Sander Mateos > --- > drivers/block/ublk_drv.c | 37 +++++++++++++++++++++-------------- > include/uapi/linux/ublk_cmd.h | 8 ++++++++ > 2 files changed, 30 insertions(+), 15 deletions(-) > > diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c > index a8030818f74a..2084bbdd2cbb 100644 > --- a/drivers/block/ublk_drv.c > +++ b/drivers/block/ublk_drv.c > @@ -68,11 +68,12 @@ > | UBLK_F_ZONED \ > | UBLK_F_USER_RECOVERY_FAIL_IO \ > | UBLK_F_UPDATE_SIZE \ > | UBLK_F_AUTO_BUF_REG \ > | UBLK_F_QUIESCE \ > - | UBLK_F_PER_IO_DAEMON) > + | UBLK_F_PER_IO_DAEMON \ > + | UBLK_F_BUF_REG_OFF_DAEMON) > > #define UBLK_F_ALL_RECOVERY_FLAGS (UBLK_F_USER_RECOVERY \ > | UBLK_F_USER_RECOVERY_REISSUE \ > | UBLK_F_USER_RECOVERY_FAIL_IO) > > @@ -2018,20 +2019,10 @@ static int ublk_register_io_buf(struct io_uring_cmd *cmd, > } > > return 0; > } > > -static int ublk_unregister_io_buf(struct io_uring_cmd *cmd, > - const struct ublk_queue *ubq, > - unsigned int index, unsigned int issue_flags) > -{ > - if (!ublk_support_zero_copy(ubq)) > - return -EINVAL; > - > - return io_buffer_unregister_bvec(cmd, index, issue_flags); > -} > - > static int ublk_fetch(struct io_uring_cmd *cmd, struct ublk_queue *ubq, > struct ublk_io *io, __u64 buf_addr) > { > struct ublk_device *ub = ubq->dev; > int ret = 0; > @@ -2184,10 +2175,18 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd, > > ret = ublk_check_cmd_op(cmd_op); > if (ret) > goto out; > > + /* > + * io_buffer_unregister_bvec() doesn't access the ubq or io, > + * so no need to validate the q_id, tag, or task > + */ > + if (_IOC_NR(cmd_op) == UBLK_IO_UNREGISTER_IO_BUF) > + return io_buffer_unregister_bvec(cmd, ub_cmd->addr, > + issue_flags); > + Yeah, the behavior looks correct, but I'd suggest to validate the q_id too for making code more robust. Also you removed ublk_support_zero_copy() check for unregistering io buffer command, which isn't expected for this patch. > ret = -EINVAL; > if (ub_cmd->q_id >= ub->dev_info.nr_hw_queues) > goto out; > > ubq = ublk_get_queue(ub, ub_cmd->q_id); > @@ -2204,12 +2203,21 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd, > > ublk_prep_cancel(cmd, issue_flags, ubq, tag); > return -EIOCBQUEUED; > } > > - if (READ_ONCE(io->task) != current) > + if (READ_ONCE(io->task) != current) { > + /* > + * ublk_register_io_buf() accesses only the request, not io, > + * so can be handled on any task > + */ > + if (_IOC_NR(cmd_op) == UBLK_IO_REGISTER_IO_BUF) > + return ublk_register_io_buf(cmd, ubq, tag, ub_cmd->addr, > + issue_flags); Maybe you can move UBLK_IO_UNREGISTER_IO_BUF handling here, which seems more readable. Thanks, Ming