From 2151249eaabb48151cff6364adb4054b3497d62d Mon Sep 17 00:00:00 2001 From: Joe Thornber Date: Thu, 22 Sep 2016 10:44:41 -0400 Subject: dm bitset: add dm_bitset_new() A more efficient way of creating a populated bitset. Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer --- drivers/md/persistent-data/dm-bitset.c | 42 ++++++++++++++++++++++++++++++++++ drivers/md/persistent-data/dm-bitset.h | 16 +++++++++++++ 2 files changed, 58 insertions(+) (limited to 'drivers/md') diff --git a/drivers/md/persistent-data/dm-bitset.c b/drivers/md/persistent-data/dm-bitset.c index 7cb28516cc19..fbf8d9bc4d15 100644 --- a/drivers/md/persistent-data/dm-bitset.c +++ b/drivers/md/persistent-data/dm-bitset.c @@ -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) diff --git a/drivers/md/persistent-data/dm-bitset.h b/drivers/md/persistent-data/dm-bitset.h index 017c0d42cdbf..a08636898a43 100644 --- a/drivers/md/persistent-data/dm-bitset.h +++ b/drivers/md/persistent-data/dm-bitset.h @@ -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. * -- cgit v1.2.3-59-g8ed1b