Il 03/07/2012 04:49, Vivek Goyal ha scritto:

quoted

quoted

+	/* Zero-sector (unknown) and one-sector granularities are the same.  */
+	granularity = max(q->limits.discard_granularity >> 9, 1U);
+
 	/*
 	 * Ensure that max_discard_sectors is of the proper
 	 * granularity
 	 */
 	max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
+	max_discard_sectors = round_down(max_discard_sectors, granularity);
 	if (unlikely(!max_discard_sectors)) {
 		/* Avoid infinite loop below. Being cautious never hurts. */
 		return -EOPNOTSUPP;
-	} else if (q->limits.discard_granularity) {
-		unsigned int disc_sects = q->limits.discard_granularity >> 9;
-
-		max_discard_sectors &= ~(disc_sects - 1);

This is kind of odd. If discard_granularity is zero, we assume that
discards are supported and granularity is 1. But if max_discard_sectors
is zero, we assume discards are disabled. Not sure if we should treat
max_discard_sectors and discard_granularity in same way or not.

Yes, this keeps the same behavior as before.  It is also the one that is
consistent with drivers/scsi/sd.c.  sd_config_discard always sets
limits.discard_granularity and then uses limits.max_discard_sectors to
disable discards.

Paolo

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