From: Keith Busch <kbusch@xxxxxxxxxx>
When multiple partitions are used, you may want to enforce different
subsets of the available write hints for each partition. Provide a
bitmap attribute of the available write hints, and allow an admin to
write a different mask to set the partition's allowed write hints.
Signed-off-by: Keith Busch <kbusch@xxxxxxxxxx>
---
Documentation/ABI/stable/sysfs-block | 7 +++++
block/bdev.c | 17 +++++++++++
block/partitions/core.c | 45 ++++++++++++++++++++++++++--
include/linux/blk_types.h | 1 +
4 files changed, 68 insertions(+), 2 deletions(-)
diff --git a/Documentation/ABI/stable/sysfs-block b/Documentation/ABI/stable/sysfs-block
index f2db2cabb8e75..fa2db6b638d63 100644
--- a/Documentation/ABI/stable/sysfs-block
+++ b/Documentation/ABI/stable/sysfs-block
@@ -187,6 +187,13 @@ Description:
partition is offset from the internal allocation unit's
natural alignment.
+What: /sys/block/<disk>/<partition>/write_hint_mask
+Date: October 2024
+Contact: linux-block@xxxxxxxxxxxxxxx
+Description:
+ The mask of allowed write hints. You can limit which hints the
+ block layer will use by writing a new mask. Only the first
+ partition can access all the write hints by default.
What: /sys/block/<disk>/<partition>/stat
Date: February 2008
diff --git a/block/bdev.c b/block/bdev.c
index 9a59f0c882170..e6f9d19db599b 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -415,6 +415,7 @@ void __init bdev_cache_init(void)
struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
{
struct block_device *bdev;
+ unsigned short write_hint;
struct inode *inode;
inode = new_inode(blockdev_superblock);
@@ -440,6 +441,22 @@ struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
return NULL;
}
bdev->bd_disk = disk;
+
+ write_hint = bdev_max_write_hints(bdev);
+ if (write_hint) {
+ bdev->write_hint_mask = bitmap_alloc(write_hint, GFP_KERNEL);
+ if (!bdev->write_hint_mask) {
+ free_percpu(bdev->bd_stats);
+ iput(inode);
+ return NULL;
+ }
+
+ if (partno == 1)
+ bitmap_set(bdev->write_hint_mask, 0, write_hint);
+ else
+ bitmap_clear(bdev->write_hint_mask, 0, write_hint);
+ }
+
return bdev;
}
diff --git a/block/partitions/core.c b/block/partitions/core.c
index 815ed33caa1b8..c71a5d34339d7 100644
--- a/block/partitions/core.c
+++ b/block/partitions/core.c
@@ -203,6 +203,41 @@ static ssize_t part_discard_alignment_show(struct device *dev,
return sprintf(buf, "%u\n", bdev_discard_alignment(dev_to_bdev(dev)));
}
+static ssize_t part_write_hint_mask_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct block_device *bdev = dev_to_bdev(dev);
+ unsigned short max_write_hints = bdev_max_write_hints(bdev);
+
+ if (!max_write_hints)
+ return sprintf(buf, "0");
+ return sprintf(buf, "%*pb\n", max_write_hints, bdev->write_hint_mask);
+}
+
+static ssize_t part_write_hint_mask_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct block_device *bdev = dev_to_bdev(dev);
+ unsigned short max_write_hints = bdev_max_write_hints(bdev);
+ unsigned long *new_mask;
+
+ if (!max_write_hints)
+ return count;
+
+ new_mask = bitmap_alloc(max_write_hints, GFP_KERNEL);
+ if (!new_mask)
+ return -ENOMEM;
+
+ bitmap_parse(buf, count, new_mask, max_write_hints);
+ bitmap_copy(bdev->write_hint_mask, new_mask, max_write_hints);
+ smp_wmb();
+ bitmap_free(new_mask);
+
+ return count;
+}
+
static DEVICE_ATTR(partition, 0444, part_partition_show, NULL);
static DEVICE_ATTR(start, 0444, part_start_show, NULL);
static DEVICE_ATTR(size, 0444, part_size_show, NULL);
@@ -211,6 +246,8 @@ static DEVICE_ATTR(alignment_offset, 0444, part_alignment_offset_show, NULL);
static DEVICE_ATTR(discard_alignment, 0444, part_discard_alignment_show, NULL);
static DEVICE_ATTR(stat, 0444, part_stat_show, NULL);
static DEVICE_ATTR(inflight, 0444, part_inflight_show, NULL);
+static DEVICE_ATTR(write_hint_mask, 0644, part_write_hint_mask_show,
+ part_write_hint_mask_store);
#ifdef CONFIG_FAIL_MAKE_REQUEST
static struct device_attribute dev_attr_fail =
__ATTR(make-it-fail, 0644, part_fail_show, part_fail_store);
@@ -225,6 +262,7 @@ static struct attribute *part_attrs[] = {
&dev_attr_discard_alignment.attr,
&dev_attr_stat.attr,
&dev_attr_inflight.attr,
+ &dev_attr_write_hint_mask.attr,
#ifdef CONFIG_FAIL_MAKE_REQUEST
&dev_attr_fail.attr,
#endif
@@ -245,8 +283,11 @@ static const struct attribute_group *part_attr_groups[] = {
static void part_release(struct device *dev)
{
- put_disk(dev_to_bdev(dev)->bd_disk);
- bdev_drop(dev_to_bdev(dev));
+ struct block_device *part = dev_to_bdev(dev);
+
+ bitmap_free(part->write_hint_mask);
+ put_disk(part->bd_disk);
+ bdev_drop(part);
}
static int part_uevent(const struct device *dev, struct kobj_uevent_env *env)
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 6737795220e18..af430e543f7f7 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -73,6 +73,7 @@ struct block_device {
#ifdef CONFIG_SECURITY
void *bd_security;
#endif
+ unsigned long *write_hint_mask;
/*
* keep this out-of-line as it's both big and not needed in the fast
* path
--
2.43.5
