Commit 3194e364 authored by John Garry's avatar John Garry Committed by Mikulas Patocka
Browse files

dm-table: atomic writes support 



Support stacking atomic write limits for DM devices.

All the pre-existing code in blk_stack_atomic_writes_limits() already takes
care of finding the aggregrate limits from the bottom devices.

Feature flag DM_TARGET_ATOMIC_WRITES is introduced so that atomic writes
can be enabled on personalities selectively. This is to ensure that atomic
writes are only enabled when verified to be working properly (for a
specific personality). In addition, it just may not make sense to enable
atomic writes on some personalities (so this flag also helps there).

Signed-off-by: default avatarJohn Garry <john.g.garry@oracle.com>
Reviewed-by: default avatarMike Snitzer <snitzer@kernel.org>
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
parent a3842593

drivers/md/dm-table.c

+29 −0
Original line number Diff line number Diff line
@@ -1806,6 +1806,32 @@ static bool dm_table_supports_secure_erase(struct dm_table *t) 
	return true;

}



static int device_not_atomic_write_capable(struct dm_target *ti,

			struct dm_dev *dev, sector_t start,

			sector_t len, void *data)

{

	return !bdev_can_atomic_write(dev->bdev);

}



static bool dm_table_supports_atomic_writes(struct dm_table *t)

{

	for (unsigned int i = 0; i < t->num_targets; i++) {

		struct dm_target *ti = dm_table_get_target(t, i);



		if (!dm_target_supports_atomic_writes(ti->type))

			return false;



		if (!ti->type->iterate_devices)

			return false;



		if (ti->type->iterate_devices(ti,

			device_not_atomic_write_capable, NULL)) {

			return false;

		}

	}

	return true;

}



int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,

			      struct queue_limits *limits)

{
@@ -1854,6 +1880,9 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q, 
			return r;

	}



	if (dm_table_supports_atomic_writes(t))

		limits->features |= BLK_FEAT_ATOMIC_WRITES;



	r = queue_limits_set(q, limits);

	if (r)

		return r;

include/linux/device-mapper.h

+3 −0
Original line number Diff line number Diff line
@@ -299,6 +299,9 @@ struct target_type { 
#define dm_target_supports_mixed_zoned_model(type) (false)

#endif



#define DM_TARGET_ATOMIC_WRITES		0x00000400

#define dm_target_supports_atomic_writes(type) ((type)->features & DM_TARGET_ATOMIC_WRITES)



struct dm_target {

	struct dm_table *table;

	struct target_type *type;

include/uapi/linux/dm-ioctl.h

+2 −2
Original line number Diff line number Diff line
@@ -286,9 +286,9 @@ enum { 
#define DM_DEV_SET_GEOMETRY	_IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)



#define DM_VERSION_MAJOR	4

#define DM_VERSION_MINOR	48

#define DM_VERSION_MINOR	49

#define DM_VERSION_PATCHLEVEL	0

#define DM_VERSION_EXTRA	"-ioctl (2023-03-01)"

#define DM_VERSION_EXTRA	"-ioctl (2025-01-17)"



/* Status bits */

#define DM_READONLY_FLAG	(1 << 0) /* In/Out */