[RFC PATCH -next v3 06/10] dm: add BLK_FEAT_WRITE_ZEROES_UNMAP support

Zhang Yi
2025-03-18T07:44:16Z

From: Zhang Yi <yi.zhang@huawei.com>

Set the BLK_FEAT_WRITE_ZEROES_UNMAP feature on stacking queue limits by
default. This feature shall be disabled if any underlying device does
not support it.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
drivers/md/dm-table.c | 7 +++++--
drivers/md/dm.c | 1 +
2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 453803f1edf5..d4a483287e26 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -598,7 +598,8 @@ int dm_split_args(int *argc, char ***argvp, char *input)
static void dm_set_stacking_limits(struct queue_limits *limits)
{
blk_set_stacking_limits(limits);
- limits->features |= BLK_FEAT_IO_STAT | BLK_FEAT_NOWAIT | BLK_FEAT_POLL;
+ limits->features |= BLK_FEAT_IO_STAT | BLK_FEAT_NOWAIT | BLK_FEAT_POLL |
+ BLK_FEAT_WRITE_ZEROES_UNMAP;
}

/*
@@ -1848,8 +1849,10 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
limits->discard_alignment = 0;
}

- if (!dm_table_supports_write_zeroes(t))
+ if (!dm_table_supports_write_zeroes(t)) {
limits->max_write_zeroes_sectors = 0;
+ limits->features &= ~BLK_FEAT_WRITE_ZEROES_UNMAP;
+ }

if (!dm_table_supports_secure_erase(t))
limits->max_secure_erase_sectors = 0;
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 5ab7574c0c76..b59c3dbeaaf1 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1096,6 +1096,7 @@ void disable_write_zeroes(struct mapped_device *md)

/* device doesn't really support WRITE ZEROES, disable it */
limits->max_write_zeroes_sectors = 0;
+ limits->features &= ~BLK_FEAT_WRITE_ZEROES_UNMAP;
}

static bool swap_bios_limit(struct dm_target *ti, struct bio *bio)
--
2.46.1