Messages in this thread | | | Date | Wed, 02 Sep 2015 12:48:58 +0200 | From | Matias Bjørling <> | Subject | Re: [PATCH v7 1/5] lightnvm: Support for Open-Channel SSDs |
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>> + >> + /* register with device with a supported BM */ >> + list_for_each_entry(bt, &nvm_bms, list) { >> + ret = bt->register_bm(dev); >> + if (ret < 0) >> + goto err; /* initialization failed */ >> + if (ret > 0) { >> + dev->bm = bt; >> + break; /* successfully initialized */ >> + } >> + } > > Why just search it from head to tail? Can user specific it > in nvm_create_target()?
Hi Yang,
Currently only the rrpc and a couple of out of tree block managers are built. The register_bm only tries to find a block manager that supports the device, when it finds it, that one is initialized. It is an open question on how we choose the right block manager, e.g. a proprietary and a open-source block manager is in place. Priorities might be a way to go? or mark certain block managers as a catch all?
Hopefully we will get away with only a single or two block managers in the future, so we won't have one for each type of device.
>> + >> + if (!ret) { >> + pr_info("nvm: no compatible bm was found.\n"); >> + return 0; >> + } > > If we allow nvm_device registered with no bm, we would get > a NULL pointer reference problem in later using. >
Yes, definitely. In the care that happens, I envision it should be possible to register a block manager after a device is loaded, and then any outstanding devices (which does not have a registered block manager), will be probed again.
> As mentioned above, why we have to choose bm for nvm in nvm_register?
Without a block manager, we don't know the structure of the device and how to interact with it. I want to initialize that as soon as possible. So that layers on top can start interacting.
> > Thanx > Yang
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