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

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Date:   Thu, 15 Aug 2019 10:02:47 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     Max Gurtovoy <maxg@...lanox.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 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@....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.

OK, queued up for v8.

Thanks,

Logan