Re: [PATCH v7 07/14] nvmet-passthru: add enable/disable helpers

[Logan Gunthorpe]

On 2019-08-15 6:20 a.m., Max Gurtovoy wrote:
> 
> 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@xxxxxxx: this patch is very roughly based
>> Â on a similar one by Chaitanya]
>> Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@xxxxxxx>
>> Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
>> ---
>> Â drivers/nvme/target/core.cÂÂÂÂÂÂÂÂÂÂÂ |Â 8 +++
>> Â drivers/nvme/target/io-cmd-passthru.c | 77 +++++++++++++++++++++++++++
>> Â drivers/nvme/target/nvmet.hÂÂÂÂÂÂÂÂÂÂ | 10 ++++
>> Â 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)
>> Â ÂÂÂÂÂ mutex_lock(&subsys->lock);
>> ÂÂÂÂÂ ret = 0;
>> +
>> +ÂÂÂ if (nvmet_passthru_ctrl(subsys)) {
>> +ÂÂÂÂÂÂÂ pr_info("cannot enable both passthru and regular namespaces
>> for a single subsystem");
>> +ÂÂÂÂÂÂÂ goto out_unlock;
>> +ÂÂÂ }
>> +
>> ÂÂÂÂÂ if (ns->enabled)
>> ÂÂÂÂÂÂÂÂÂ goto out_unlock;
>> Â @@ -1439,6 +1445,8 @@ static void nvmet_subsys_free(struct kref *ref)
>> Â ÂÂÂÂÂ WARN_ON_ONCE(!list_empty(&subsys->namespaces));
>> Â +ÂÂÂ nvmet_passthru_subsys_free(subsys);
>> +
>> ÂÂÂÂÂ kfree(subsys->subsysnqn);
>> ÂÂÂÂÂ kfree(subsys);
>> Â }
>> 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 @@
>> Â #include "../host/nvme.h"
>> Â #include "nvmet.h"
>> Â +/*
>> + * xarray to maintain one passthru subsystem per nvme controller.
>> + */
>> +static DEFINE_XARRAY(passthru_subsystems);
>> +
>> Â static struct workqueue_struct *passthru_wq;
>> Â Â int nvmet_passthru_init(void)
>> @@ -27,6 +32,78 @@ void nvmet_passthru_destroy(void)
>> ÂÂÂÂÂ destroy_workqueue(passthru_wq);
>> Â }
>> Â +int nvmet_passthru_ctrl_enable(struct nvmet_subsys *subsys)
>> +{
>> +ÂÂÂ struct nvme_ctrl *ctrl;
>> +ÂÂÂ int ret = -EINVAL;
>> +ÂÂÂ void *old;
>> +
>> +ÂÂÂ mutex_lock(&subsys->lock);
>> +ÂÂÂ if (!subsys->passthru_ctrl_path)
>> +ÂÂÂÂÂÂÂ goto out_unlock;
>> +ÂÂÂ if (subsys->passthru_ctrl)
>> +ÂÂÂÂÂÂÂ goto out_unlock;
>> +
>> +ÂÂÂ if (subsys->nr_namespaces) {
>> +ÂÂÂÂÂÂÂ pr_info("cannot enable both passthru and regular namespaces
>> for a single subsystem");
>> +ÂÂÂÂÂÂÂ goto out_unlock;
>> +ÂÂÂ }
>> +
>> +ÂÂÂ ctrl = nvme_ctrl_get_by_path(subsys->passthru_ctrl_path);
>> +ÂÂÂ if (IS_ERR(ctrl)) {
>> +ÂÂÂÂÂÂÂ ret = PTR_ERR(ctrl);
>> +ÂÂÂÂÂÂÂ pr_err("failed to open nvme controller %s\n",
>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂ subsys->passthru_ctrl_path);
>> +
>> +ÂÂÂÂÂÂÂ goto out_unlock;
>> +ÂÂÂ }
>> +
>> +ÂÂÂ old = xa_cmpxchg(&passthru_subsystems, ctrl->cntlid, NULL,
>> +ÂÂÂÂÂÂÂÂÂÂÂÂ subsys, GFP_KERNEL);
>> +ÂÂÂ if (xa_is_err(old)) {
>> +ÂÂÂÂÂÂÂ ret = xa_err(old);
>> +ÂÂÂÂÂÂÂ goto out_put_ctrl;
>> +ÂÂÂ }
>> +
>> +ÂÂÂ if (old)
>> +ÂÂÂÂÂÂÂ goto out_put_ctrl;
>> +
>> +ÂÂÂ subsys->passthru_ctrl = ctrl;
>> +ÂÂÂ ret = 0;
>> +
>> +ÂÂÂ 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.

OK, queued up for v8.

Thanks,

Logan