From fdd1315aa5f022fe6574efdc2d9535f75a0ee255 Mon Sep 17 00:00:00 2001 From: Joe Thornber Date: Thu, 15 Sep 2016 11:11:42 -0400 Subject: [PATCH] dm array: introduce cursor api More efficient way to iterate an array due to prefetching (makes use of the new dm_btree_cursor_* api). Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer --- drivers/md/persistent-data/dm-array.c | 86 +++++++++++++++++++++++++++ drivers/md/persistent-data/dm-array.h | 33 ++++++++++ 2 files changed, 119 insertions(+) diff --git a/drivers/md/persistent-data/dm-array.c b/drivers/md/persistent-data/dm-array.c index 155180954cdf..e83047cbb2da 100644 --- a/drivers/md/persistent-data/dm-array.c +++ b/drivers/md/persistent-data/dm-array.c @@ -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); + +/*----------------------------------------------------------------*/ diff --git a/drivers/md/persistent-data/dm-array.h b/drivers/md/persistent-data/dm-array.h index 45ea3f6e1ded..27ee49a55473 100644 --- a/drivers/md/persistent-data/dm-array.h +++ b/drivers/md/persistent-data/dm-array.h @@ -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 */ -- 2.20.1