[PATCH v2 01/16] block: Add atomic write operations to request_queue limits

John Garry
2023-12-12T11:10:17Z

From: Himanshu Madhani <himanshu.madhani@oracle.com>

Add the following limits:
- atomic_write_boundary_bytes
- atomic_write_max_bytes
- atomic_write_unit_max_bytes
- atomic_write_unit_min_bytes

All atomic writes limits are initialised to 0 to indicate no atomic write
support. Stacked devices are just not supported either for now.

Signed-off-by: Himanshu Madhani <himanshu.madhani@oracle.com>
#jpg: Heavy rewrite
Signed-off-by: John Garry <john.g.garry@oracle.com>
---
Documentation/ABI/stable/sysfs-block | 47 ++++++++++++++++++++++
block/blk-settings.c | 60 ++++++++++++++++++++++++++++
block/blk-sysfs.c | 33 +++++++++++++++
include/linux/blkdev.h | 37 +++++++++++++++++
4 files changed, 177 insertions(+)

diff --git a/Documentation/ABI/stable/sysfs-block b/Documentation/ABI/stable/sysfs-block
index 1fe9a553c37b..ba81a081522f 100644
--- a/Documentation/ABI/stable/sysfs-block
+++ b/Documentation/ABI/stable/sysfs-block
@@ -21,6 +21,53 @@ Description:
device is offset from the internal allocation unit's
natural alignment.

+What: /sys/block/<disk>/atomic_write_max_bytes
+Date: May 2023
+Contact: Himanshu Madhani <himanshu.madhani@oracle.com>
+Description:
+ [RO] This parameter specifies the maximum atomic write
+ size reported by the device. This parameter is relevant
+ for merging of writes, where a merged atomic write
+ operation must not exceed this number of bytes.
+ The atomic_write_max_bytes may exceed the value in
+ atomic_write_unit_max_bytes if atomic_write_max_bytes
+ is not a power-of-two or atomic_write_unit_max_bytes is
+ limited by some queue limits, such as max_segments.
+
+
+What: /sys/block/<disk>/atomic_write_unit_min_bytes
+Date: May 2023
+Contact: Himanshu Madhani <himanshu.madhani@oracle.com>
+Description:
+ [RO] This parameter specifies the smallest block which can
+ be written atomically with an atomic write operation. All
+ atomic write operations must begin at a
+ atomic_write_unit_min boundary and must be multiples of
+ atomic_write_unit_min. This value must be a power-of-two.
+
+
+What: /sys/block/<disk>/atomic_write_unit_max_bytes
+Date: January 2023
+Contact: Himanshu Madhani <himanshu.madhani@oracle.com>
+Description:
+ [RO] This parameter defines the largest block which can be
+ written atomically with an atomic write operation. This
+ value must be a multiple of atomic_write_unit_min and must
+ be a power-of-two.
+
+
+What: /sys/block/<disk>/atomic_write_boundary_bytes
+Date: May 2023
+Contact: Himanshu Madhani <himanshu.madhani@oracle.com>
+Description:
+ [RO] A device may need to internally split I/Os which
+ straddle a given logical block address boundary. In that
+ case a single atomic write operation will be processed as
+ one of more sub-operations which each complete atomically.
+ This parameter specifies the size in bytes of the atomic
+ boundary if one is reported by the device. This value must
+ be a power-of-two.
+

What: /sys/block/<disk>/diskseq
Date: February 2021
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 0046b447268f..d151be394c98 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -59,6 +59,10 @@ void blk_set_default_limits(struct queue_limits *lim)
lim->zoned = BLK_ZONED_NONE;
lim->zone_write_granularity = 0;
lim->dma_alignment = 511;
+ lim->atomic_write_unit_min_sectors = 0;
+ lim->atomic_write_unit_max_sectors = 0;
+ lim->atomic_write_max_sectors = 0;
+ lim->atomic_write_boundary_sectors = 0;
}

/**
@@ -183,6 +187,62 @@ void blk_queue_max_discard_sectors(struct request_queue *q,
}
EXPORT_SYMBOL(blk_queue_max_discard_sectors);

+/**
+ * blk_queue_atomic_write_max_bytes - set max bytes supported by
+ * the device for atomic write operations.
+ * @q: the request queue for the device
+ * @size: maximum bytes supported
+ */
+void blk_queue_atomic_write_max_bytes(struct request_queue *q,
+ unsigned int bytes)
+{
+ q->limits.atomic_write_max_sectors = bytes >> SECTOR_SHIFT;
+}
+EXPORT_SYMBOL(blk_queue_atomic_write_max_bytes);
+
+/**
+ * blk_queue_atomic_write_boundary_bytes - Device's logical block address space
+ * which an atomic write should not cross.
+ * @q: the request queue for the device
+ * @bytes: must be a power-of-two.
+ */
+void blk_queue_atomic_write_boundary_bytes(struct request_queue *q,
+ unsigned int bytes)
+{
+ q->limits.atomic_write_boundary_sectors = bytes >> SECTOR_SHIFT;
+}
+EXPORT_SYMBOL(blk_queue_atomic_write_boundary_bytes);
+
+/**
+ * blk_queue_atomic_write_unit_min_sectors - smallest unit that can be written
+ * atomically to the device.
+ * @q: the request queue for the device
+ * @sectors: must be a power-of-two.
+ */
+void blk_queue_atomic_write_unit_min_sectors(struct request_queue *q,
+ unsigned int sectors)
+{
+ struct queue_limits *limits = &q->limits;
+
+ limits->atomic_write_unit_min_sectors = sectors;
+}
+EXPORT_SYMBOL(blk_queue_atomic_write_unit_min_sectors);
+
+/*
+ * blk_queue_atomic_write_unit_max_sectors - largest unit that can be written
+ * atomically to the device.
+ * @q: the request queue for the device
+ * @sectors: must be a power-of-two.
+ */
+void blk_queue_atomic_write_unit_max_sectors(struct request_queue *q,
+ unsigned int sectors)
+{
+ struct queue_limits *limits = &q->limits;
+
+ limits->atomic_write_unit_max_sectors = sectors;
+}
+EXPORT_SYMBOL(blk_queue_atomic_write_unit_max_sectors);
+
/**
* blk_queue_max_secure_erase_sectors - set max sectors for a secure erase
* @q: the request queue for the device
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 0b2d04766324..4ebf148cf356 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -118,6 +118,30 @@ static ssize_t queue_max_discard_segments_show(struct request_queue *q,
return queue_var_show(queue_max_discard_segments(q), page);
}

+static ssize_t queue_atomic_write_max_bytes_show(struct request_queue *q,
+ char *page)
+{
+ return queue_var_show(queue_atomic_write_max_bytes(q), page);
+}
+
+static ssize_t queue_atomic_write_boundary_show(struct request_queue *q,
+ char *page)
+{
+ return queue_var_show(queue_atomic_write_boundary_bytes(q), page);
+}
+
+static ssize_t queue_atomic_write_unit_min_show(struct request_queue *q,
+ char *page)
+{
+ return queue_var_show(queue_atomic_write_unit_min_bytes(q), page);
+}
+
+static ssize_t queue_atomic_write_unit_max_show(struct request_queue *q,
+ char *page)
+{
+ return queue_var_show(queue_atomic_write_unit_max_bytes(q), page);
+}
+
static ssize_t queue_max_integrity_segments_show(struct request_queue *q, char *page)
{
return queue_var_show(q->limits.max_integrity_segments, page);
@@ -507,6 +531,11 @@ QUEUE_RO_ENTRY(queue_discard_max_hw, "discard_max_hw_bytes");
QUEUE_RW_ENTRY(queue_discard_max, "discard_max_bytes");
QUEUE_RO_ENTRY(queue_discard_zeroes_data, "discard_zeroes_data");

+QUEUE_RO_ENTRY(queue_atomic_write_max_bytes, "atomic_write_max_bytes");
+QUEUE_RO_ENTRY(queue_atomic_write_boundary, "atomic_write_boundary_bytes");
+QUEUE_RO_ENTRY(queue_atomic_write_unit_max, "atomic_write_unit_max_bytes");
+QUEUE_RO_ENTRY(queue_atomic_write_unit_min, "atomic_write_unit_min_bytes");
+
QUEUE_RO_ENTRY(queue_write_same_max, "write_same_max_bytes");
QUEUE_RO_ENTRY(queue_write_zeroes_max, "write_zeroes_max_bytes");
QUEUE_RO_ENTRY(queue_zone_append_max, "zone_append_max_bytes");
@@ -634,6 +663,10 @@ static struct attribute *queue_attrs[] = {
&queue_discard_max_entry.attr,
&queue_discard_max_hw_entry.attr,
&queue_discard_zeroes_data_entry.attr,
+ &queue_atomic_write_max_bytes_entry.attr,
+ &queue_atomic_write_boundary_entry.attr,
+ &queue_atomic_write_unit_min_entry.attr,
+ &queue_atomic_write_unit_max_entry.attr,
&queue_write_same_max_entry.attr,
&queue_write_zeroes_max_entry.attr,
&queue_zone_append_max_entry.attr,
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 51fa7ffdee83..ab53163dd187 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -309,6 +309,11 @@ struct queue_limits {
unsigned int discard_alignment;
unsigned int zone_write_granularity;

+ unsigned int atomic_write_boundary_sectors;
+ unsigned int atomic_write_max_sectors;
+ unsigned int atomic_write_unit_min_sectors;
+ unsigned int atomic_write_unit_max_sectors;
+
unsigned short max_segments;
unsigned short max_integrity_segments;
unsigned short max_discard_segments;
@@ -908,6 +913,14 @@ void blk_queue_zone_write_granularity(struct request_queue *q,
unsigned int size);
extern void blk_queue_alignment_offset(struct request_queue *q,
unsigned int alignment);
+void blk_queue_atomic_write_max_bytes(struct request_queue *q,
+ unsigned int bytes);
+void blk_queue_atomic_write_unit_max_sectors(struct request_queue *q,
+ unsigned int sectors);
+void blk_queue_atomic_write_unit_min_sectors(struct request_queue *q,
+ unsigned int sectors);
+void blk_queue_atomic_write_boundary_bytes(struct request_queue *q,
+ unsigned int bytes);
void disk_update_readahead(struct gendisk *disk);
extern void blk_limits_io_min(struct queue_limits *limits, unsigned int min);
extern void blk_queue_io_min(struct request_queue *q, unsigned int min);
@@ -1312,6 +1325,30 @@ static inline int queue_dma_alignment(const struct request_queue *q)
return q ? q->limits.dma_alignment : 511;
}

+static inline unsigned int
+queue_atomic_write_unit_max_bytes(const struct request_queue *q)
+{
+ return q->limits.atomic_write_unit_max_sectors << SECTOR_SHIFT;
+}
+
+static inline unsigned int
+queue_atomic_write_unit_min_bytes(const struct request_queue *q)
+{
+ return q->limits.atomic_write_unit_min_sectors << SECTOR_SHIFT;
+}
+
+static inline unsigned int
+queue_atomic_write_boundary_bytes(const struct request_queue *q)
+{
+ return q->limits.atomic_write_boundary_sectors << SECTOR_SHIFT;
+}
+
+static inline unsigned int
+queue_atomic_write_max_bytes(const struct request_queue *q)
+{
+ return q->limits.atomic_write_max_sectors << SECTOR_SHIFT;
+}
+
static inline unsigned int bdev_dma_alignment(struct block_device *bdev)
{
return queue_dma_alignment(bdev_get_queue(bdev));
--
2.35.3