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Date: Thu, 15 Aug 2019 15:20:35 +0300
From: Max Gurtovoy <maxg@...lanox.com>
To: Logan Gunthorpe <logang@...tatee.com>,
<linux-kernel@...r.kernel.org>, <linux-nvme@...ts.infradead.org>,
<linux-block@...r.kernel.org>, <linux-fsdevel@...r.kernel.org>
CC: Christoph Hellwig <hch@....de>, Sagi Grimberg <sagi@...mberg.me>,
"Keith Busch" <kbusch@...nel.org>, Jens Axboe <axboe@...com>,
Chaitanya Kulkarni <Chaitanya.Kulkarni@....com>,
Stephen Bates <sbates@...thlin.com>
Subject: Re: [PATCH v7 07/14] nvmet-passthru: add enable/disable helpers
On 8/2/2019 2:45 AM, Logan Gunthorpe wrote:
> This patch adds helper functions which are used in the NVMeOF configfs
> when the user is configuring the passthru subsystem. Here we ensure
> that only one subsys is assigned to each nvme_ctrl by using an xarray
> on the cntlid.
>
> [chaitanya.kulkarni@....com: this patch is very roughly based
> on a similar one by Chaitanya]
> Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@....com>
> Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
> ---
> drivers/nvme/target/core.c | 8 +++
> drivers/nvme/target/io-cmd-passthru.c | 77 +++++++++++++++++++++++++++
> drivers/nvme/target/nvmet.h | 10 ++++
> 3 files changed, 95 insertions(+)
>
> diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
> index 50c01b2da568..2e75968af7f4 100644
> --- a/drivers/nvme/target/core.c
> +++ b/drivers/nvme/target/core.c
> @@ -519,6 +519,12 @@ int nvmet_ns_enable(struct nvmet_ns *ns)
>
> mutex_lock(&subsys->lock);
> ret = 0;
> +
> + if (nvmet_passthru_ctrl(subsys)) {
> + pr_info("cannot enable both passthru and regular namespaces for a single subsystem");
> + goto out_unlock;
> + }
> +
> if (ns->enabled)
> goto out_unlock;
>
> @@ -1439,6 +1445,8 @@ static void nvmet_subsys_free(struct kref *ref)
>
> WARN_ON_ONCE(!list_empty(&subsys->namespaces));
>
> + nvmet_passthru_subsys_free(subsys);
> +
> kfree(subsys->subsysnqn);
> kfree(subsys);
> }
> diff --git a/drivers/nvme/target/io-cmd-passthru.c b/drivers/nvme/target/io-cmd-passthru.c
> index 46c58fec5608..b199785500ad 100644
> --- a/drivers/nvme/target/io-cmd-passthru.c
> +++ b/drivers/nvme/target/io-cmd-passthru.c
> @@ -11,6 +11,11 @@
> #include "../host/nvme.h"
> #include "nvmet.h"
>
> +/*
> + * xarray to maintain one passthru subsystem per nvme controller.
> + */
> +static DEFINE_XARRAY(passthru_subsystems);
> +
> static struct workqueue_struct *passthru_wq;
>
> int nvmet_passthru_init(void)
> @@ -27,6 +32,78 @@ void nvmet_passthru_destroy(void)
> destroy_workqueue(passthru_wq);
> }
>
> +int nvmet_passthru_ctrl_enable(struct nvmet_subsys *subsys)
> +{
> + struct nvme_ctrl *ctrl;
> + int ret = -EINVAL;
> + void *old;
> +
> + mutex_lock(&subsys->lock);
> + if (!subsys->passthru_ctrl_path)
> + goto out_unlock;
> + if (subsys->passthru_ctrl)
> + goto out_unlock;
> +
> + if (subsys->nr_namespaces) {
> + pr_info("cannot enable both passthru and regular namespaces for a single subsystem");
> + goto out_unlock;
> + }
> +
> + ctrl = nvme_ctrl_get_by_path(subsys->passthru_ctrl_path);
> + if (IS_ERR(ctrl)) {
> + ret = PTR_ERR(ctrl);
> + pr_err("failed to open nvme controller %s\n",
> + subsys->passthru_ctrl_path);
> +
> + goto out_unlock;
> + }
> +
> + old = xa_cmpxchg(&passthru_subsystems, ctrl->cntlid, NULL,
> + subsys, GFP_KERNEL);
> + if (xa_is_err(old)) {
> + ret = xa_err(old);
> + goto out_put_ctrl;
> + }
> +
> + if (old)
> + goto out_put_ctrl;
> +
> + subsys->passthru_ctrl = ctrl;
> + ret = 0;
> +
> + goto out_unlock;
can we re-arrange the code here ?
it's not so common to see goto in a good flow.
maybe have 1 good flow the goto's will go bellow it as we usually do in
this subsystem.
> +
> +out_put_ctrl:
> + nvme_put_ctrl(ctrl);
> +out_unlock:
> + mutex_unlock(&subsys->lock);
> + return ret;
> +}
> +
> +static void __nvmet_passthru_ctrl_disable(struct nvmet_subsys *subsys)
> +{
> + if (subsys->passthru_ctrl) {
> + xa_erase(&passthru_subsystems, subsys->passthru_ctrl->cntlid);
> + nvme_put_ctrl(subsys->passthru_ctrl);
> + }
> + subsys->passthru_ctrl = NULL;
> +}
> +
> +void nvmet_passthru_ctrl_disable(struct nvmet_subsys *subsys)
> +{
> + mutex_lock(&subsys->lock);
> + __nvmet_passthru_ctrl_disable(subsys);
> + mutex_unlock(&subsys->lock);
> +}
> +
> +void nvmet_passthru_subsys_free(struct nvmet_subsys *subsys)
> +{
> + mutex_lock(&subsys->lock);
> + __nvmet_passthru_ctrl_disable(subsys);
> + kfree(subsys->passthru_ctrl_path);
> + mutex_unlock(&subsys->lock);
> +}
> +
> static void nvmet_passthru_req_complete(struct nvmet_req *req,
> struct request *rq, u16 status)
> {
> diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
> index bd11114ebbb9..aff4db03269d 100644
> --- a/drivers/nvme/target/nvmet.h
> +++ b/drivers/nvme/target/nvmet.h
> @@ -230,6 +230,7 @@ struct nvmet_subsys {
>
> #ifdef CONFIG_NVME_TARGET_PASSTHRU
> struct nvme_ctrl *passthru_ctrl;
> + char *passthru_ctrl_path;
> #endif /* CONFIG_NVME_TARGET_PASSTHRU */
> };
>
> @@ -509,6 +510,9 @@ static inline u32 nvmet_rw_len(struct nvmet_req *req)
>
> int nvmet_passthru_init(void);
> void nvmet_passthru_destroy(void);
> +void nvmet_passthru_subsys_free(struct nvmet_subsys *subsys);
> +int nvmet_passthru_ctrl_enable(struct nvmet_subsys *subsys);
> +void nvmet_passthru_ctrl_disable(struct nvmet_subsys *subsys);
> u16 nvmet_parse_passthru_cmd(struct nvmet_req *req);
>
> static inline
> @@ -526,6 +530,12 @@ static inline int nvmet_passthru_init(void)
> static inline void nvmet_passthru_destroy(void)
> {
> }
> +static inline void nvmet_passthru_subsys_free(struct nvmet_subsys *subsys)
> +{
> +}
> +static inline void nvmet_passthru_ctrl_disable(struct nvmet_subsys *subsys)
> +{
> +}
> static inline u16 nvmet_parse_passthru_cmd(struct nvmet_req *req)
> {
> return 0;
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