Re: [PATCH v3] block/gluster: correctly set max_pdiscard

[Eric Blake]

On Fri, May 20, 2022 at 09:59:22AM +0200, Fabian Ebner wrote:
> On 64-bit platforms, assigning SIZE_MAX to the int64_t max_pdiscard
> results in a negative value, and the following assertion would trigger
> down the line (it's not the same max_pdiscard, but computed from the
> other one):
> qemu-system-x86_64: ../block/io.c:3166: bdrv_co_pdiscard: Assertion
> `max_pdiscard >= bs->bl.request_alignment' failed.
> 
> On 32-bit platforms, it's fine to keep using SIZE_MAX.
> 
> The assertion in qemu_gluster_co_pdiscard() is checking that the value
> of 'bytes' can safely be passed to glfs_discard_async(), which takes a
> size_t for the argument in question, so it is kept as is. And since
> max_pdiscard is still <= SIZE_MAX, relying on max_pdiscard is still
> fine.
> 
> Fixes: 0c8022876f ("block: use int64_t instead of int in driver discard 
> handlers")
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
> ---

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
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