block: Expose discard granularity

While SSDs track block usage on a per-sector basis, RAID arrays often
have allocation blocks that are bigger.  Allow the discard granularity
and alignment to be set and teach the topology stacking logic how to
handle them.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index 7b685e10cbad..64bc8998ac9a 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -226,6 +226,13 @@ ssize_t part_alignment_offset_show(struct device *dev,
         return sprintf(buf, "%llu\n", (unsigned long long)p->alignment_offset);
 }
 
+ssize_t part_discard_alignment_show(struct device *dev,
+                                   struct device_attribute *attr, char *buf)
+{
+        struct hd_struct *p = dev_to_part(dev);
+        return sprintf(buf, "%u\n", p->discard_alignment);
+}
+
 ssize_t part_stat_show(struct device *dev,
                        struct device_attribute *attr, char *buf)
 {
@@ -288,6 +295,8 @@ static DEVICE_ATTR(partition, S_IRUGO, part_partition_show, NULL);
 static DEVICE_ATTR(start, S_IRUGO, part_start_show, NULL);
 static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL);
 static DEVICE_ATTR(alignment_offset, S_IRUGO, part_alignment_offset_show, NULL);
+static DEVICE_ATTR(discard_alignment, S_IRUGO, part_discard_alignment_show,
+                   NULL);
 static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL);
 static DEVICE_ATTR(inflight, S_IRUGO, part_inflight_show, NULL);
 #ifdef CONFIG_FAIL_MAKE_REQUEST
@@ -300,6 +309,7 @@ static struct attribute *part_attrs[] = {
         &dev_attr_start.attr,
         &dev_attr_size.attr,
         &dev_attr_alignment_offset.attr,
+        &dev_attr_discard_alignment.attr,
         &dev_attr_stat.attr,
         &dev_attr_inflight.attr,
 #ifdef CONFIG_FAIL_MAKE_REQUEST
@@ -403,6 +413,8 @@ struct hd_struct *add_partition(struct gendisk *disk, int partno,
 
         p->start_sect = start;
         p->alignment_offset = queue_sector_alignment_offset(disk->queue, start);
+        p->discard_alignment = queue_sector_discard_alignment(disk->queue,
+                                                              start);
         p->nr_sects = len;
         p->partno = partno;
         p->policy = get_disk_ro(disk);