tools/hv: fcopy: Fix irregularities with size of ring buffer

Size of ring buffer, as defined in uio_hv_generic driver, is no longer
fixed to 16 KB. This creates a problem in fcopy, since this size was
hardcoded. With the change in place to make ring sysfs node actually
reflect the size of underlying ring buffer, it is safe to get the size
of ring sysfs file and use it for ring buffer size in fcopy daemon.
Fix the issue of disparity in ring buffer size, by making it dynamic
in fcopy uio daemon.

Cc: stable@vger.kernel.org
Fixes: 0315fef2 ("uio_hv_generic: Align ring size to system page")
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Reviewed-by: Long Li <longli@microsoft.com>
Link: https://lore.kernel.org/r/20250711060846.9168-1-namjain@linux.microsoft.com


Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20250711060846.9168-1-namjain@linux.microsoft.com>