On Tue, 2016-07-19 at 15:25 +0200, Hannes Reinecke wrote:
> For ZBC devices I/O must not cross zone boundaries, so setup
> the 'chunk_sectors' block queue setting to the zone size.
> This is only valid for REPORT ZONES SAME type 2 or 3;
> for other types the zone sizes might be different
> for individual zones. So issue a warning if the type is
> found to be different.
> Also the capacity might be different from the announced
> capacity, so adjust it as needed.
>
> Signed-off-by: Hannes Reinecke <hare@xxxxxxxx>
...
> +static void sd_read_zones(struct scsi_disk *sdkp, unsigned char *buffer)
> +{
> + int retval;
> + unsigned char *desc;
> + u32 rep_len;
> + u8 same;
> + u64 zone_len, lba;
> +
> + if (sdkp->zoned != 1)
> + /* Device managed, no special handling required */
> + return;
> +
> + retval = sd_zbc_report_zones(sdkp, buffer, SD_BUF_SIZE,
> + 0, ZBC_ZONE_REPORTING_OPTION_ALL, false);
> + if (retval < 0)
> + return;
> +
> + rep_len = get_unaligned_be32(&buffer[0]);
> + if (rep_len < 64) {
> + sd_printk(KERN_WARNING, sdkp,
> + "REPORT ZONES report invalid length %u\n",
> + rep_len);
> + return;
> + }
> +
> + if (sdkp->rc_basis == 0) {
> + /* The max_lba field is the capacity of a zoned device */
> + lba = get_unaligned_be64(&buffer[8]);
> + if (lba + 1 > sdkp->capacity) {
> + sd_printk(KERN_WARNING, sdkp,
> + "Max LBA %zu (capacity %zu)\n",
> + (sector_t) lba + 1, sdkp->capacity);
> + sdkp->capacity = lba + 1;
> + }
> + }
> +
> + /*
> + * Adjust 'chunk_sectors' to the zone length if the device
> + * supports equal zone sizes.
> + */
> + same = buffer[4] & 0xf;
> + if (same == 0 || same > 3) {
> + sd_printk(KERN_WARNING, sdkp,
> + "REPORT ZONES SAME type %d not supported\n", same);
> + return;
> + }
> + /* Read the zone length from the first zone descriptor */
> + desc = &buffer[64];
> + zone_len = logical_to_sectors(sdkp->device,
> + get_unaligned_be64(&desc[8]));
> + blk_queue_chunk_sectors(sdkp->disk->queue, zone_len);
> +}
> +
So, blk_queue_chunk_sectors() has:
void blk_queue_chunk_sectors(struct request_queue *q, unsigned int chunk_sectors)
{
BUG_ON(!is_power_of_2(chunk_sectors));
q->limits.chunk_sectors = chunk_sectors;
}
and it seems like if some device reports a non-power-of-2 zone_len then we
will BUG_ON(). Probably would be better if we reported an error instead?
-Ewan
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