Re: [Qemu-devel] [PATCH v3 04/19] nbd/server: Hoist length check to qemp_nbd_server_add

[Eric Blake]

On 1/12/19 11:57 AM, Eric Blake wrote:

s/qemp/qmp/ in the subject line

> We only had two callers to nbd_export_new; qemu-nbd.c always
> passed a valid offset/length pair (because it already checked
> the file length, to ensure that offset was in bounds), while
> blockdev-nbd always passed 0/-1.  Then nbd_export_new reduces
> the size to a multiple of BDRV_SECTOR_SIZE (can only happen
> when offset is not sector-aligned, since bdrv_getlength()
> currently rounds up), which can result in offset being greater
> than the enforced length, but that's not fatal (the server
> rejects client requests that exceed the advertised length).
> 
> However, I'm finding it easier to work with the code if we are
> consistent on having both callers pass in a valid length, and
> just assert that things are sane in nbd_export_new.
> 
-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

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