xfs: support sub-block aligned vectors in always COW mode

xfs: support sub-block aligned vectors in always COW mode

Now that the block layer and iomap have grown support to indicate
the bio sector size explicitly instead of assuming the device sector
size, we can ask for logical block size alignment and thus support
direct I/O writes where the overall size is logical block size
aligned, but the boundaries between vectors might not be.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20251031131045.1613229-3-hch@lst.de
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>