drivers/md/persistent-data/dm-space-map-metadata.c

Source file repositories/reference/linux-study-clean/drivers/md/persistent-data/dm-space-map-metadata.c

File Facts

System
Linux kernel
Corpus path
drivers/md/persistent-data/dm-space-map-metadata.c
Extension
.c
Size
17976 bytes
Lines
847
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 threshold {
	bool threshold_set;
	bool value_set;
	dm_block_t threshold;
	dm_block_t current_value;
	dm_sm_threshold_fn fn;
	void *context;
};

static void threshold_init(struct threshold *t)
{
	t->threshold_set = false;
	t->value_set = false;
}

static void set_threshold(struct threshold *t, dm_block_t value,
			  dm_sm_threshold_fn fn, void *context)
{
	t->threshold_set = true;
	t->threshold = value;
	t->fn = fn;
	t->context = context;
}

static bool below_threshold(struct threshold *t, dm_block_t value)
{
	return t->threshold_set && value <= t->threshold;
}

static bool threshold_already_triggered(struct threshold *t)
{
	return t->value_set && below_threshold(t, t->current_value);
}

static void check_threshold(struct threshold *t, dm_block_t value)
{
	if (below_threshold(t, value) &&
	    !threshold_already_triggered(t))
		t->fn(t->context);

	t->value_set = true;
	t->current_value = value;
}

/*----------------------------------------------------------------*/

/*
 * Space map interface.
 *
 * The low level disk format is written using the standard btree and
 * transaction manager.  This means that performing disk operations may
 * cause us to recurse into the space map in order to allocate new blocks.
 * For this reason we have a pool of pre-allocated blocks large enough to
 * service any metadata_ll_disk operation.
 */

/*
 * FIXME: we should calculate this based on the size of the device.
 * Only the metadata space map needs this functionality.
 */
#define MAX_RECURSIVE_ALLOCATIONS 1024

enum block_op_type {
	BOP_INC,
	BOP_DEC
};

struct block_op {
	enum block_op_type type;
	dm_block_t b;
	dm_block_t e;
};

struct bop_ring_buffer {
	unsigned int begin;
	unsigned int end;
	struct block_op bops[MAX_RECURSIVE_ALLOCATIONS + 1];
};

static void brb_init(struct bop_ring_buffer *brb)
{
	brb->begin = 0;
	brb->end = 0;
}

static bool brb_empty(struct bop_ring_buffer *brb)
{
	return brb->begin == brb->end;
}

Annotation

Implementation Notes