multiple of sector size I/O restriction

[Jean-Yves Lefort]

In sys/geom/geom_io.c, g_io_check() I find this:

		/* Reject I/O not on sector boundary */
		if (bp->bio_offset % pp->sectorsize)
			return (EINVAL);

Which causes this:

	# dd if=/dev/ad1 of=test bs=512 count=1
	1+0 records in
	1+0 records out
	512 bytes transferred in 1.889527 secs (271 bytes/sec)

	# dd if=/dev/ad1 of=test bs=513 count=1
	dd: /dev/ad1: Invalid argument
	0+0 records in
	0+0 records out
	0 bytes transferred in 0.000254 secs (0 bytes/sec)

Why this restriction?

-- 
Jean-Yves Lefort

jylefort at FreeBSD.org
http://lefort.be.eu.org/
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