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authorJoe Thornber <ejt@redhat.com>2016-09-22 10:44:41 -0400
committerMike Snitzer <snitzer@redhat.com>2017-02-16 13:12:48 -0500
commit2151249eaabb48151cff6364adb4054b3497d62d (patch)
tree26ae3dba9537c44fbf6436f31015f1fd33b68098 /drivers/md
parent48551054fc256285289f6d03abd50cb74fb71819 (diff)
downloadlinux-2151249eaabb48151cff6364adb4054b3497d62d.tar.bz2
dm bitset: add dm_bitset_new()
A more efficient way of creating a populated bitset. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/persistent-data/dm-bitset.c42
-rw-r--r--drivers/md/persistent-data/dm-bitset.h16
2 files changed, 58 insertions, 0 deletions
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
@@ -93,6 +93,22 @@ 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.
*
* info - describes the bitset