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Commit 2151249e authored by Joe Thornber's avatar Joe Thornber Committed by Mike Snitzer
Browse files

dm bitset: add dm_bitset_new() 



A more efficient way of creating a populated bitset.

Signed-off-by: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 48551054

drivers/md/persistent-data/dm-bitset.c

+42 −0
Original line number Diff line number Diff line
@@ -39,6 +39,48 @@ int dm_bitset_empty(struct dm_disk_bitset *info, dm_block_t *root) 
}

EXPORT_SYMBOL_GPL(dm_bitset_empty);



struct packer_context {

	bit_value_fn fn;

	unsigned nr_bits;

	void *context;

};



static int pack_bits(uint32_t index, void *value, void *context)

{

	int r;

	struct packer_context *p = context;

	unsigned bit, nr = min(64u, p->nr_bits - (index * 64));

	uint64_t word = 0;

	bool bv;



	for (bit = 0; bit < nr; bit++) {

		r = p->fn(index * 64 + bit, &bv, p->context);

		if (r)

			return r;



		if (bv)

			set_bit(bit, (unsigned long *) &word);

		else

			clear_bit(bit, (unsigned long *) &word);

	}



	*((__le64 *) value) = cpu_to_le64(word);



	return 0;

}



int dm_bitset_new(struct dm_disk_bitset *info, dm_block_t *root,

		  uint32_t size, bit_value_fn fn, void *context)

{

	struct packer_context p;

	p.fn = fn;

	p.nr_bits = size;

	p.context = context;



	return dm_array_new(&info->array_info, root, dm_div_up(size, 64), pack_bits, &p);

}

EXPORT_SYMBOL_GPL(dm_bitset_new);



int dm_bitset_resize(struct dm_disk_bitset *info, dm_block_t root,

		     uint32_t old_nr_entries, uint32_t new_nr_entries,

		     bool default_value, dm_block_t *new_root)

drivers/md/persistent-data/dm-bitset.h

+16 −0
Original line number Diff line number Diff line
@@ -92,6 +92,22 @@ void dm_disk_bitset_init(struct dm_transaction_manager *tm, 
 */

int dm_bitset_empty(struct dm_disk_bitset *info, dm_block_t *new_root);



/*

 * Creates a new bitset populated with values provided by a callback

 * function.  This is more efficient than creating an empty bitset,

 * resizing, and then setting values since that process incurs a lot of

 * copying.

 *

 * info - describes the array

 * root - the root block of the array on disk

 * size - the number of entries in the array

 * fn - the callback

 * context - passed to the callback

 */

typedef int (*bit_value_fn)(uint32_t index, bool *value, void *context);

int dm_bitset_new(struct dm_disk_bitset *info, dm_block_t *root,

		  uint32_t size, bit_value_fn fn, void *context);



/*

 * Resize the bitset.

 *