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>
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 66d4aa8..7f986ca 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -96,7 +96,10 @@
lim->max_segment_size = MAX_SEGMENT_SIZE;
lim->max_sectors = BLK_DEF_MAX_SECTORS;
lim->max_hw_sectors = INT_MAX;
- lim->max_discard_sectors = SAFE_MAX_SECTORS;
+ lim->max_discard_sectors = 0;
+ lim->discard_granularity = 0;
+ lim->discard_alignment = 0;
+ lim->discard_misaligned = 0;
lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT);
lim->alignment_offset = 0;
@@ -488,6 +491,16 @@
}
EXPORT_SYMBOL(blk_queue_stack_limits);
+static unsigned int lcm(unsigned int a, unsigned int b)
+{
+ if (a && b)
+ return (a * b) / gcd(a, b);
+ else if (b)
+ return b;
+
+ return a;
+}
+
/**
* blk_stack_limits - adjust queue_limits for stacked devices
* @t: the stacking driver limits (top)
@@ -502,6 +515,10 @@
int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
sector_t offset)
{
+ int ret;
+
+ ret = 0;
+
t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors);
t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn);
@@ -531,7 +548,13 @@
if (offset &&
(offset & (b->physical_block_size - 1)) != b->alignment_offset) {
t->misaligned = 1;
- return -1;
+ ret = -1;
+ }
+
+ if (offset &&
+ (offset & (b->discard_granularity - 1)) != b->discard_alignment) {
+ t->discard_misaligned = 1;
+ ret = -1;
}
/* If top has no alignment offset, inherit from bottom */
@@ -539,23 +562,26 @@
t->alignment_offset =
b->alignment_offset & (b->physical_block_size - 1);
+ if (!t->discard_alignment)
+ t->discard_alignment =
+ b->discard_alignment & (b->discard_granularity - 1);
+
/* Top device aligned on logical block boundary? */
if (t->alignment_offset & (t->logical_block_size - 1)) {
t->misaligned = 1;
- return -1;
+ ret = -1;
}
- /* Find lcm() of optimal I/O size */
- if (t->io_opt && b->io_opt)
- t->io_opt = (t->io_opt * b->io_opt) / gcd(t->io_opt, b->io_opt);
- else if (b->io_opt)
- t->io_opt = b->io_opt;
+ /* Find lcm() of optimal I/O size and granularity */
+ t->io_opt = lcm(t->io_opt, b->io_opt);
+ t->discard_granularity = lcm(t->discard_granularity,
+ b->discard_granularity);
/* Verify that optimal I/O size is a multiple of io_min */
if (t->io_min && t->io_opt % t->io_min)
- return -1;
+ ret = -1;
- return 0;
+ return ret;
}
EXPORT_SYMBOL(blk_stack_limits);
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 8a6d81a..3147145 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -126,6 +126,16 @@
return queue_var_show(queue_io_opt(q), page);
}
+static ssize_t queue_discard_granularity_show(struct request_queue *q, char *page)
+{
+ return queue_var_show(q->limits.discard_granularity, page);
+}
+
+static ssize_t queue_discard_max_show(struct request_queue *q, char *page)
+{
+ return queue_var_show(q->limits.max_discard_sectors << 9, page);
+}
+
static ssize_t
queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
{
@@ -293,6 +303,16 @@
.show = queue_io_opt_show,
};
+static struct queue_sysfs_entry queue_discard_granularity_entry = {
+ .attr = {.name = "discard_granularity", .mode = S_IRUGO },
+ .show = queue_discard_granularity_show,
+};
+
+static struct queue_sysfs_entry queue_discard_max_entry = {
+ .attr = {.name = "discard_max_bytes", .mode = S_IRUGO },
+ .show = queue_discard_max_show,
+};
+
static struct queue_sysfs_entry queue_nonrot_entry = {
.attr = {.name = "rotational", .mode = S_IRUGO | S_IWUSR },
.show = queue_nonrot_show,
@@ -328,6 +348,8 @@
&queue_physical_block_size_entry.attr,
&queue_io_min_entry.attr,
&queue_io_opt_entry.attr,
+ &queue_discard_granularity_entry.attr,
+ &queue_discard_max_entry.attr,
&queue_nonrot_entry.attr,
&queue_nomerges_entry.attr,
&queue_rq_affinity_entry.attr,
diff --git a/block/genhd.c b/block/genhd.c
index 517e433..b11a4ad 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -861,12 +861,23 @@
return sprintf(buf, "%d\n", queue_alignment_offset(disk->queue));
}
+static ssize_t disk_discard_alignment_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct gendisk *disk = dev_to_disk(dev);
+
+ return sprintf(buf, "%u\n", queue_discard_alignment(disk->queue));
+}
+
static DEVICE_ATTR(range, S_IRUGO, disk_range_show, NULL);
static DEVICE_ATTR(ext_range, S_IRUGO, disk_ext_range_show, NULL);
static DEVICE_ATTR(removable, S_IRUGO, disk_removable_show, NULL);
static DEVICE_ATTR(ro, S_IRUGO, disk_ro_show, NULL);
static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL);
static DEVICE_ATTR(alignment_offset, S_IRUGO, disk_alignment_offset_show, NULL);
+static DEVICE_ATTR(discard_alignment, S_IRUGO, disk_discard_alignment_show,
+ NULL);
static DEVICE_ATTR(capability, S_IRUGO, disk_capability_show, NULL);
static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL);
static DEVICE_ATTR(inflight, S_IRUGO, part_inflight_show, NULL);
@@ -887,6 +898,7 @@
&dev_attr_ro.attr,
&dev_attr_size.attr,
&dev_attr_alignment_offset.attr,
+ &dev_attr_discard_alignment.attr,
&dev_attr_capability.attr,
&dev_attr_stat.attr,
&dev_attr_inflight.attr,