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dm array: introduce cursor api

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More efficient way to iterate an array due to prefetching (makes use of
the new dm_btree_cursor_* api).

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Joe Thornber 2016-09-15 11:11:42 -04:00 committed by Mike Snitzer
parent 7d111c81fa
commit fdd1315aa5
2 changed files with 119 additions and 0 deletions
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86
drivers/md/persistent-data/dm-array.c
View File

@ -899,3 +899,89 @@ int dm_array_walk(struct dm_array_info *info, dm_block_t root,
EXPORT_SYMBOL_GPL(dm_array_walk);
/*----------------------------------------------------------------*/
static int load_ablock(struct dm_array_cursor *c)
{
int r;
__le64 value_le;
uint64_t key;
if (c->block)
unlock_ablock(c->info, c->block);
c->block = NULL;
c->ab = NULL;
c->index = 0;
r = dm_btree_cursor_get_value(&c->cursor, &key, &value_le);
if (r) {
DMERR("dm_btree_cursor_get_value failed");
dm_btree_cursor_end(&c->cursor);
} else {
r = get_ablock(c->info, le64_to_cpu(value_le), &c->block, &c->ab);
if (r) {
DMERR("get_ablock failed");
dm_btree_cursor_end(&c->cursor);
}
}
return r;
}
int dm_array_cursor_begin(struct dm_array_info *info, dm_block_t root,
struct dm_array_cursor *c)
{
int r;
memset(c, 0, sizeof(*c));
c->info = info;
r = dm_btree_cursor_begin(&info->btree_info, root, true, &c->cursor);
if (r) {
DMERR("couldn't create btree cursor");
return r;
}
return load_ablock(c);
}
EXPORT_SYMBOL_GPL(dm_array_cursor_begin);
void dm_array_cursor_end(struct dm_array_cursor *c)
{
if (c->block) {
unlock_ablock(c->info, c->block);
dm_btree_cursor_end(&c->cursor);
}
}
EXPORT_SYMBOL_GPL(dm_array_cursor_end);
int dm_array_cursor_next(struct dm_array_cursor *c)
{
int r;
if (!c->block)
return -ENODATA;
c->index++;
if (c->index >= le32_to_cpu(c->ab->nr_entries)) {
r = dm_btree_cursor_next(&c->cursor);
if (r)
return r;
r = load_ablock(c);
if (r)
return r;
}
return 0;
}
EXPORT_SYMBOL_GPL(dm_array_cursor_next);
void dm_array_cursor_get_value(struct dm_array_cursor *c, void **value_le)
{
*value_le = element_at(c->info, c->ab, c->index);
}
EXPORT_SYMBOL_GPL(dm_array_cursor_get_value);
/*----------------------------------------------------------------*/

33
drivers/md/persistent-data/dm-array.h
View File

@ -182,4 +182,37 @@ int dm_array_walk(struct dm_array_info *info, dm_block_t root,
/*----------------------------------------------------------------*/
/*
* Cursor api.
*
* This lets you iterate through all the entries in an array efficiently
* (it will preload metadata).
*
* I'm using a cursor, rather than a walk function with a callback because
* the cache target needs to iterate both the mapping and hint arrays in
* unison.
*/
struct dm_array_cursor {
struct dm_array_info *info;
struct dm_btree_cursor cursor;
struct dm_block *block;
struct array_block *ab;
unsigned index;
};
int dm_array_cursor_begin(struct dm_array_info *info,
dm_block_t root, struct dm_array_cursor *c);
void dm_array_cursor_end(struct dm_array_cursor *c);
uint32_t dm_array_cursor_index(struct dm_array_cursor *c);
int dm_array_cursor_next(struct dm_array_cursor *c);
/*
* value_le is only valid while the cursor points at the current value.
*/
void dm_array_cursor_get_value(struct dm_array_cursor *c, void **value_le);
/*----------------------------------------------------------------*/
#endif /* _LINUX_DM_ARRAY_H */