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Re: kern/55674: ld(4) should attempt to allocate ld(4) for 0 size disks
The following reply was made to PR kern/55674; it has been noted by GNATS.
From: Frank Kardel <kardel%netbsd.org@localhost>
Subject: Re: kern/55674: ld(4) should attempt to allocate ld(4) for 0 size
Date: Mon, 21 Sep 2020 14:02:07 +0200
Yepp - the data size = 1 comes from the blind 1 << lbads(==0) expression
(nvmectl). lbads == 0 means not available.
ld_attach() attempts to bail out on this condition, which is, as I
agree, too late.
We should fix nvme_rescan() in ic/nvme.c to do the inquiriy part and
initial check from
ld_nvme.c:ld_nvme_attach(). Unfortunately this introduces one additional
valid namespace. But that is better than to allocate 13k mostly dead
ld(4) instances for just 3 devices.
On 09/21/20 12:55, Michael van Elst wrote:
> The following reply was made to PR kern/55674; it has been noted by GNATS.
> From: mlelstv%serpens.de@localhost (Michael van Elst)
> To: gnats-bugs%netbsd.org@localhost
> Subject: Re: kern/55674: ld(4) should attempt to allocate ld(4) for 0 size disks
> Date: Mon, 21 Sep 2020 10:51:59 -0000 (UTC)
> kardel%netbsd.org@localhost (Frank Kardel) writes:
> >> nvmectl identify nvme0ns2
> >> Size (in LBAs): 0 (0M)
> >> Capacity (in LBAs): 0 (0M)
> >> Utilization (in LBAs): 0 (0M)
> >> Thin Provisioning: Not Supported
> >> Number of LBA Formats: 1
> >> Current LBA Format: LBA Format #00
> >> LBA Format #00: Data Size: 1 Metadata Size: 0
> A size of zero is perfectly valid, but a "data size" of 1 (byte per block)
> is invalid.
> The ld(4) attachment already fails with that data size, but since this
> happens within the attach routine that cannot signal failure, the ld(4)
> units are still created.
> A workaround would be to issue the identify command and check the format
> already in the nvme driver. As long as ld(4) is the only child for nvme
> this shouldn't cause any problems.
> Michael van Elst
> Internet: mlelstv%serpens.de@localhost
> "A potential Snark may lurk in every tree."
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