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,
diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index 7b685e1..64bc899 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -226,6 +226,13 @@
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(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 @@
&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 @@
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);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 39c601f..1cc0297 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -312,12 +312,15 @@
unsigned int io_min;
unsigned int io_opt;
unsigned int max_discard_sectors;
+ unsigned int discard_granularity;
+ unsigned int discard_alignment;
unsigned short logical_block_size;
unsigned short max_hw_segments;
unsigned short max_phys_segments;
unsigned char misaligned;
+ unsigned char discard_misaligned;
unsigned char no_cluster;
};
@@ -1121,6 +1124,21 @@
return q->limits.alignment_offset;
}
+static inline int queue_discard_alignment(struct request_queue *q)
+{
+ if (q->limits.discard_misaligned)
+ return -1;
+
+ return q->limits.discard_alignment;
+}
+
+static inline int queue_sector_discard_alignment(struct request_queue *q,
+ sector_t sector)
+{
+ return ((sector << 9) - q->limits.discard_alignment)
+ & (q->limits.discard_granularity - 1);
+}
+
static inline int queue_dma_alignment(struct request_queue *q)
{
return q ? q->dma_alignment : 511;
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 297df45..c6c0c41 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -91,6 +91,7 @@
sector_t start_sect;
sector_t nr_sects;
sector_t alignment_offset;
+ unsigned int discard_alignment;
struct device __dev;
struct kobject *holder_dir;
int policy, partno;
