drivers/md/dm-snap-transient.c

Source file repositories/reference/linux-study-clean/drivers/md/dm-snap-transient.c

File Facts

System
Linux kernel
Corpus path
drivers/md/dm-snap-transient.c
Extension
.c
Size
3829 bytes
Lines
159
Domain
Driver Families
Bucket
drivers/md
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct transient_c {
	sector_t next_free;
};

static void transient_dtr(struct dm_exception_store *store)
{
	kfree(store->context);
}

static int transient_read_metadata(struct dm_exception_store *store,
				   int (*callback)(void *callback_context,
						   chunk_t old, chunk_t new),
				   void *callback_context)
{
	return 0;
}

static int transient_prepare_exception(struct dm_exception_store *store,
				       struct dm_exception *e)
{
	struct transient_c *tc = store->context;
	sector_t size = get_dev_size(dm_snap_cow(store->snap)->bdev);

	if (size < (tc->next_free + store->chunk_size))
		return -1;

	e->new_chunk = sector_to_chunk(store, tc->next_free);
	tc->next_free += store->chunk_size;

	return 0;
}

static void transient_commit_exception(struct dm_exception_store *store,
				       struct dm_exception *e, int valid,
				       void (*callback)(void *, int success),
				       void *callback_context)
{
	/* Just succeed */
	callback(callback_context, valid);
}

static void transient_usage(struct dm_exception_store *store,
			    sector_t *total_sectors,
			    sector_t *sectors_allocated,
			    sector_t *metadata_sectors)
{
	*sectors_allocated = ((struct transient_c *) store->context)->next_free;
	*total_sectors = get_dev_size(dm_snap_cow(store->snap)->bdev);
	*metadata_sectors = 0;
}

static int transient_ctr(struct dm_exception_store *store, char *options)
{
	struct transient_c *tc;

	tc = kmalloc_obj(struct transient_c);
	if (!tc)
		return -ENOMEM;

	tc->next_free = 0;
	store->context = tc;

	return 0;
}

static unsigned int transient_status(struct dm_exception_store *store,
				 status_type_t status, char *result,
				 unsigned int maxlen)
{
	unsigned int sz = 0;

	switch (status) {
	case STATUSTYPE_INFO:
		break;
	case STATUSTYPE_TABLE:
		DMEMIT(" N %llu", (unsigned long long)store->chunk_size);
		break;
	case STATUSTYPE_IMA:
		*result = '\0';
		break;
	}

	return sz;
}

static struct dm_exception_store_type _transient_type = {
	.name = "transient",
	.module = THIS_MODULE,
	.ctr = transient_ctr,
	.dtr = transient_dtr,

Annotation

Implementation Notes