[sheepdog] [PATCH v2 01/17] block/throttle-groups: throttle_group_co_io_limits_intercept(): 64bit bytes
eblake at redhat.com
Mon Apr 27 16:12:12 CEST 2020
On 4/27/20 5:05 AM, Philippe Mathieu-Daudé wrote:
> On 4/27/20 10:23 AM, Vladimir Sementsov-Ogievskiy wrote:
>> The function is called from 64bit io handlers, and bytes is just passed
>> to throttle_account() which is 64bit too (unsigned though). So, let's
>> convert intermediate argument to 64bit too.
> What is the meaning of negative bytes in this function?
An error. It is more for consistency, in that we really cannot access
more than 63 bits of size information (off_t is signed, and network
protocols don't magically add a 64th bit to that underlying inherent
limitation of files and block devices).
It may be worth adding assert(bytes >= 0), if that makes it easier to
prove we are only dealing with positive lengths.
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
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