On Wed, Dec 18, 2024 at 11:34:34AM -0500, Steven Sistare wrote:
> After adding resizable support to qemu_ram_alloc_from_fd, I can also tweak it
> to grow the file while preserving error checking for the general case, and
> delete the explicit ftruncate in its caller:
>
> /*
> * Allow file_ram_alloc to grow the file during CPR, if a resizable
> * memory region wants a larger block than the incoming current size.
> */
> file_size = get_file_size(fd);
> if (file_size && file_size < offset + max_size && size == max_size &&
> migrate_mode() != MIG_MODE_CPR_TRANSFER) {
Firstly, this check is growing too long, maybe worthwhile to have a helper
already.
file_size_check():
// COMMENTS...
if (migrate_mode() == XXX) {
return true;
}
Said that, I think it's better we also add the flag to enforce the
truncation, only if cpr found a fd. E.g. we may want to keep the old
behavior even if the user sets migrate mode to CPR (even without a
migration happening at all), then create a fd ramblock.
> error_setg(errp, "backing store size 0x%" PRIx64
> " does not match 'size' option 0x" RAM_ADDR_FMT,
> file_size, max_size);
> return NULL;
> }
> ...
> new_block->host = file_ram_alloc(new_block, max_size, fd,
> file_size < offset + max_size,
> offset, errp);
>
> - Steve
>
--
Peter Xu
