libfuse: fix COPY_FILE_RANGE interface

The FUSE protocol uses struct fuse_write_out to convey the return value of
copy_file_range, which is restricted to uint32_t.  But the COPY_FILE_RANGE
interface supports a 64-bit size copies.

Currently the number of bytes copied is silently truncated to 32-bit, which
is unfortunate at best.

Implement the COPY_FILE_RANGE_64 interface which is identical to the old
one, except the number of bytes copied is returned in a 64-bit value.

The library interface remains the same.

If the kernel does not support the new interface or the server is running
as a 32-bit process, limit the copy size to size to UINT_MAX - 4096.

Edit by Bernd:
Keep ioctl_64bit and add use new bit is_copy_file_range_64 to keep
flags separated from each other - easier code readability IMO.

Reported-by: Florian Weimer <fweimer@redhat.com>
Closes: https://lore.kernel.org/all/lhuh5ynl8z5.fsf@oldenburg.str.redhat.com/
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Bernd Schubert <bschubert@ddn.com>

0 files changed, 0 insertions, 0 deletions