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: John Garry <[email protected]> --- drivers/md/dm-table.c | 29 +++++++++++++++++++++++++++++ include/linux/device-mapper.h | 3 +++ 2 files changed, 32 insertions(+) diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index bd8b796ae683..0ef5203387b2 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -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; diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index 8321f65897f3..bcc6d7b69470 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -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; -- 2.31.1
