[PATCH v18 12/21] dm: add finalize hook to target_type

Fan Wu
2024-05-03T22:32:37Z

This patch adds a target finalize hook.

The hook is triggered just before activating an inactive table of a
mapped device. If it returns an error the __bind get cancelled.

The dm-verity target will use this hook to attach the dm-verity's
roothash metadata to the block_device struct of the mapped device.

Signed-off-by: Fan Wu <wufan@linux.microsoft.com>

---
v1-v10:
+ Not present

v11:
+ Introduced

v12:
+ No changes

v13:
+ No changes

v14:
+ Add documentation

v15:
+ No changes

v16:
+ No changes

v17:
+ No changes

v18:
+ No changes
---
drivers/md/dm.c | 12 ++++++++++++
include/linux/device-mapper.h | 9 +++++++++
2 files changed, 21 insertions(+)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 7d0746b37c8e..a748c3735156 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2276,6 +2276,18 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
goto out;
}

+ for (unsigned int i = 0; i < t->num_targets; i++) {
+ struct dm_target *ti = dm_table_get_target(t, i);
+
+ if (ti->type->finalize) {
+ ret = ti->type->finalize(ti);
+ if (ret) {
+ old_map = ERR_PTR(ret);
+ goto out;
+ }
+ }
+ }
+
old_map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock));
rcu_assign_pointer(md->map, (void *)t);
md->immutable_target_type = dm_table_get_immutable_target_type(t);
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 82b2195efaca..ad368904b1d5 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -160,6 +160,14 @@ typedef int (*dm_dax_zero_page_range_fn)(struct dm_target *ti, pgoff_t pgoff,
*/
typedef size_t (*dm_dax_recovery_write_fn)(struct dm_target *ti, pgoff_t pgoff,
void *addr, size_t bytes, struct iov_iter *i);
+/*
+ * This hook allows DM targets in an inactive table to complete their setup
+ * before the table is made active.
+ * Returns:
+ * < 0 : error
+ * = 0 : success
+ */
+typedef int (*dm_finalize_fn) (struct dm_target *target);

void dm_error(const char *message);

@@ -210,6 +218,7 @@ struct target_type {
dm_dax_direct_access_fn direct_access;
dm_dax_zero_page_range_fn dax_zero_page_range;
dm_dax_recovery_write_fn dax_recovery_write;
+ dm_finalize_fn finalize;

/* For internal device-mapper use. */
struct list_head list;
--
2.44.0