int btrfs_test_free_space_cache(void)
{
struct btrfs_block_group_cache *cache;
int ret;
test_msg("Running btrfs free space cache tests\n");
cache = init_test_block_group();
if (!cache) {
test_msg("Couldn't run the tests\n");
return 0;
}
ret = test_extents(cache);
if (ret)
goto out;
ret = test_bitmaps(cache);
if (ret)
goto out;
ret = test_bitmaps_and_extents(cache);
if (ret)
goto out;
out:
__btrfs_remove_free_space_cache(cache->free_space_ctl);
kfree(cache->free_space_ctl);
kfree(cache);
test_msg("Free space cache tests finished\n");
return ret;
}
int btrfs_test_free_space_cache(void)
{
struct btrfs_block_group_cache *cache;
struct btrfs_root *root = NULL;
int ret = -ENOMEM;
test_msg("Running btrfs free space cache tests\n");
cache = init_test_block_group();
if (!cache) {
test_msg("Couldn't run the tests\n");
return 0;
}
root = btrfs_alloc_dummy_root();
if (!root)
goto out;
root->fs_info = btrfs_alloc_dummy_fs_info();
if (!root->fs_info)
goto out;
root->fs_info->extent_root = root;
cache->fs_info = root->fs_info;
ret = test_extents(cache);
if (ret)
goto out;
ret = test_bitmaps(cache);
if (ret)
goto out;
ret = test_bitmaps_and_extents(cache);
if (ret)
goto out;
ret = test_steal_space_from_bitmap_to_extent(cache);
out:
__btrfs_remove_free_space_cache(cache->free_space_ctl);
kfree(cache->free_space_ctl);
kfree(cache);
btrfs_free_dummy_root(root);
test_msg("Free space cache tests finished\n");
return ret;
}
/*
* Before we were able to steal free space from a bitmap entry to an extent
* entry, we could end up with 2 entries representing a contiguous free space.
* One would be an extent entry and the other a bitmap entry. Since in order
* to allocate space to a caller we use only 1 entry, we couldn't return that
* whole range to the caller if it was requested. This forced the caller to
* either assume ENOSPC or perform several smaller space allocations, which
* wasn't optimal as they could be spread all over the block group while under
* concurrency (extra overhead and fragmentation).
*
* This stealing approach is beneficial, since we always prefer to allocate
* from extent entries, both for clustered and non-clustered allocation
* requests.
*/
static int
test_steal_space_from_bitmap_to_extent(struct btrfs_block_group_cache *cache,
u32 sectorsize)
{
int ret;
u64 offset;
u64 max_extent_size;
const struct btrfs_free_space_op test_free_space_ops = {
.recalc_thresholds = cache->free_space_ctl->op->recalc_thresholds,
.use_bitmap = test_use_bitmap,
};
const struct btrfs_free_space_op *orig_free_space_ops;
test_msg("Running space stealing from bitmap to extent\n");
/*
* For this test, we want to ensure we end up with an extent entry
* immediately adjacent to a bitmap entry, where the bitmap starts
* at an offset where the extent entry ends. We keep adding and
* removing free space to reach into this state, but to get there
* we need to reach a point where marking new free space doesn't
* result in adding new extent entries or merging the new space
* with existing extent entries - the space ends up being marked
* in an existing bitmap that covers the new free space range.
*
* To get there, we need to reach the threshold defined set at
* cache->free_space_ctl->extents_thresh, which currently is
* 256 extents on a x86_64 system at least, and a few other
* conditions (check free_space_cache.c). Instead of making the
* test much longer and complicated, use a "use_bitmap" operation
* that forces use of bitmaps as soon as we have at least 1
* extent entry.
*/
orig_free_space_ops = cache->free_space_ctl->op;
cache->free_space_ctl->op = &test_free_space_ops;
/*
* Extent entry covering free space range [128Mb - 256Kb, 128Mb - 128Kb[
*/
ret = test_add_free_space_entry(cache, SZ_128M - SZ_256K, SZ_128K, 0);
if (ret) {
test_msg("Couldn't add extent entry %d\n", ret);
return ret;
}
/* Bitmap entry covering free space range [128Mb + 512Kb, 256Mb[ */
ret = test_add_free_space_entry(cache, SZ_128M + SZ_512K,
SZ_128M - SZ_512K, 1);
if (ret) {
test_msg("Couldn't add bitmap entry %d\n", ret);
return ret;
}
ret = check_num_extents_and_bitmaps(cache, 2, 1);
if (ret)
return ret;
/*
* Now make only the first 256Kb of the bitmap marked as free, so that
* we end up with only the following ranges marked as free space:
*
* [128Mb - 256Kb, 128Mb - 128Kb[
* [128Mb + 512Kb, 128Mb + 768Kb[
*/
ret = btrfs_remove_free_space(cache,
SZ_128M + 768 * SZ_1K,
SZ_128M - 768 * SZ_1K);
if (ret) {
test_msg("Failed to free part of bitmap space %d\n", ret);
return ret;
}
/* Confirm that only those 2 ranges are marked as free. */
if (!test_check_exists(cache, SZ_128M - SZ_256K, SZ_128K)) {
test_msg("Free space range missing\n");
return -ENOENT;
}
if (!test_check_exists(cache, SZ_128M + SZ_512K, SZ_256K)) {
test_msg("Free space range missing\n");
return -ENOENT;
}
/*
* Confirm that the bitmap range [128Mb + 768Kb, 256Mb[ isn't marked
* as free anymore.
*/
if (test_check_exists(cache, SZ_128M + 768 * SZ_1K,
SZ_128M - 768 * SZ_1K)) {
test_msg("Bitmap region not removed from space cache\n");
return -EINVAL;
}
/*
* Confirm that the region [128Mb + 256Kb, 128Mb + 512Kb[, which is
* covered by the bitmap, isn't marked as free.
*/
if (test_check_exists(cache, SZ_128M + SZ_256K, SZ_256K)) {
test_msg("Invalid bitmap region marked as free\n");
return -EINVAL;
}
/*
* Confirm that the region [128Mb, 128Mb + 256Kb[, which is covered
* by the bitmap too, isn't marked as free either.
*/
if (test_check_exists(cache, SZ_128M, SZ_256K)) {
test_msg("Invalid bitmap region marked as free\n");
return -EINVAL;
}
/*
* Now lets mark the region [128Mb, 128Mb + 512Kb[ as free too. But,
* lets make sure the free space cache marks it as free in the bitmap,
* and doesn't insert a new extent entry to represent this region.
*/
ret = btrfs_add_free_space(cache, SZ_128M, SZ_512K);
if (ret) {
test_msg("Error adding free space: %d\n", ret);
return ret;
}
/* Confirm the region is marked as free. */
if (!test_check_exists(cache, SZ_128M, SZ_512K)) {
test_msg("Bitmap region not marked as free\n");
return -ENOENT;
}
/*
* Confirm that no new extent entries or bitmap entries were added to
* the cache after adding that free space region.
*/
ret = check_num_extents_and_bitmaps(cache, 2, 1);
if (ret)
return ret;
/*
* Now lets add a small free space region to the right of the previous
* one, which is not contiguous with it and is part of the bitmap too.
* The goal is to test that the bitmap entry space stealing doesn't
* steal this space region.
*/
ret = btrfs_add_free_space(cache, SZ_128M + SZ_16M, sectorsize);
if (ret) {
test_msg("Error adding free space: %d\n", ret);
return ret;
}
/*
* Confirm that no new extent entries or bitmap entries were added to
* the cache after adding that free space region.
*/
ret = check_num_extents_and_bitmaps(cache, 2, 1);
if (ret)
return ret;
/*
* Now mark the region [128Mb - 128Kb, 128Mb[ as free too. This will
* expand the range covered by the existing extent entry that represents
* the free space [128Mb - 256Kb, 128Mb - 128Kb[.
*/
ret = btrfs_add_free_space(cache, SZ_128M - SZ_128K, SZ_128K);
if (ret) {
test_msg("Error adding free space: %d\n", ret);
return ret;
}
/* Confirm the region is marked as free. */
if (!test_check_exists(cache, SZ_128M - SZ_128K, SZ_128K)) {
test_msg("Extent region not marked as free\n");
return -ENOENT;
}
/*
* Confirm that our extent entry didn't stole all free space from the
* bitmap, because of the small 4Kb free space region.
*/
ret = check_num_extents_and_bitmaps(cache, 2, 1);
if (ret)
return ret;
/*
* So now we have the range [128Mb - 256Kb, 128Mb + 768Kb[ as free
* space. Without stealing bitmap free space into extent entry space,
* we would have all this free space represented by 2 entries in the
* cache:
*
* extent entry covering range: [128Mb - 256Kb, 128Mb[
* bitmap entry covering range: [128Mb, 128Mb + 768Kb[
*
* Attempting to allocate the whole free space (1Mb) would fail, because
* we can't allocate from multiple entries.
* With the bitmap free space stealing, we get a single extent entry
* that represents the 1Mb free space, and therefore we're able to
* allocate the whole free space at once.
*/
if (!test_check_exists(cache, SZ_128M - SZ_256K, SZ_1M)) {
test_msg("Expected region not marked as free\n");
return -ENOENT;
}
if (cache->free_space_ctl->free_space != (SZ_1M + sectorsize)) {
test_msg("Cache free space is not 1Mb + %u\n", sectorsize);
return -EINVAL;
}
offset = btrfs_find_space_for_alloc(cache,
0, SZ_1M, 0,
&max_extent_size);
if (offset != (SZ_128M - SZ_256K)) {
test_msg("Failed to allocate 1Mb from space cache, returned offset is: %llu\n",
offset);
return -EINVAL;
}
/*
* All that remains is a sectorsize free space region in a bitmap.
* Confirm.
*/
ret = check_num_extents_and_bitmaps(cache, 1, 1);
if (ret)
return ret;
if (cache->free_space_ctl->free_space != sectorsize) {
test_msg("Cache free space is not %u\n", sectorsize);
return -EINVAL;
}
offset = btrfs_find_space_for_alloc(cache,
0, sectorsize, 0,
&max_extent_size);
if (offset != (SZ_128M + SZ_16M)) {
test_msg("Failed to allocate %u, returned offset : %llu\n",
sectorsize, offset);
return -EINVAL;
}
ret = check_cache_empty(cache);
if (ret)
return ret;
__btrfs_remove_free_space_cache(cache->free_space_ctl);
/*
* Now test a similar scenario, but where our extent entry is located
* to the right of the bitmap entry, so that we can check that stealing
* space from a bitmap to the front of an extent entry works.
*/
/*
* Extent entry covering free space range [128Mb + 128Kb, 128Mb + 256Kb[
*/
ret = test_add_free_space_entry(cache, SZ_128M + SZ_128K, SZ_128K, 0);
if (ret) {
test_msg("Couldn't add extent entry %d\n", ret);
return ret;
}
/* Bitmap entry covering free space range [0, 128Mb - 512Kb[ */
ret = test_add_free_space_entry(cache, 0, SZ_128M - SZ_512K, 1);
if (ret) {
test_msg("Couldn't add bitmap entry %d\n", ret);
return ret;
}
ret = check_num_extents_and_bitmaps(cache, 2, 1);
if (ret)
return ret;
/*
* Now make only the last 256Kb of the bitmap marked as free, so that
* we end up with only the following ranges marked as free space:
*
* [128Mb + 128b, 128Mb + 256Kb[
* [128Mb - 768Kb, 128Mb - 512Kb[
*/
ret = btrfs_remove_free_space(cache, 0, SZ_128M - 768 * SZ_1K);
if (ret) {
test_msg("Failed to free part of bitmap space %d\n", ret);
return ret;
}
/* Confirm that only those 2 ranges are marked as free. */
if (!test_check_exists(cache, SZ_128M + SZ_128K, SZ_128K)) {
test_msg("Free space range missing\n");
return -ENOENT;
}
if (!test_check_exists(cache, SZ_128M - 768 * SZ_1K, SZ_256K)) {
test_msg("Free space range missing\n");
return -ENOENT;
}
/*
* Confirm that the bitmap range [0, 128Mb - 768Kb[ isn't marked
* as free anymore.
*/
if (test_check_exists(cache, 0, SZ_128M - 768 * SZ_1K)) {
test_msg("Bitmap region not removed from space cache\n");
return -EINVAL;
}
/*
* Confirm that the region [128Mb - 512Kb, 128Mb[, which is
* covered by the bitmap, isn't marked as free.
*/
if (test_check_exists(cache, SZ_128M - SZ_512K, SZ_512K)) {
test_msg("Invalid bitmap region marked as free\n");
return -EINVAL;
}
/*
* Now lets mark the region [128Mb - 512Kb, 128Mb[ as free too. But,
* lets make sure the free space cache marks it as free in the bitmap,
* and doesn't insert a new extent entry to represent this region.
*/
ret = btrfs_add_free_space(cache, SZ_128M - SZ_512K, SZ_512K);
if (ret) {
test_msg("Error adding free space: %d\n", ret);
return ret;
}
/* Confirm the region is marked as free. */
if (!test_check_exists(cache, SZ_128M - SZ_512K, SZ_512K)) {
test_msg("Bitmap region not marked as free\n");
return -ENOENT;
}
/*
* Confirm that no new extent entries or bitmap entries were added to
* the cache after adding that free space region.
*/
ret = check_num_extents_and_bitmaps(cache, 2, 1);
if (ret)
return ret;
/*
* Now lets add a small free space region to the left of the previous
* one, which is not contiguous with it and is part of the bitmap too.
* The goal is to test that the bitmap entry space stealing doesn't
* steal this space region.
*/
ret = btrfs_add_free_space(cache, SZ_32M, 2 * sectorsize);
if (ret) {
test_msg("Error adding free space: %d\n", ret);
return ret;
}
/*
* Now mark the region [128Mb, 128Mb + 128Kb[ as free too. This will
* expand the range covered by the existing extent entry that represents
* the free space [128Mb + 128Kb, 128Mb + 256Kb[.
*/
ret = btrfs_add_free_space(cache, SZ_128M, SZ_128K);
if (ret) {
test_msg("Error adding free space: %d\n", ret);
return ret;
}
/* Confirm the region is marked as free. */
if (!test_check_exists(cache, SZ_128M, SZ_128K)) {
test_msg("Extent region not marked as free\n");
return -ENOENT;
}
/*
* Confirm that our extent entry didn't stole all free space from the
* bitmap, because of the small 2 * sectorsize free space region.
*/
ret = check_num_extents_and_bitmaps(cache, 2, 1);
if (ret)
return ret;
/*
* So now we have the range [128Mb - 768Kb, 128Mb + 256Kb[ as free
* space. Without stealing bitmap free space into extent entry space,
* we would have all this free space represented by 2 entries in the
* cache:
*
* extent entry covering range: [128Mb, 128Mb + 256Kb[
* bitmap entry covering range: [128Mb - 768Kb, 128Mb[
*
* Attempting to allocate the whole free space (1Mb) would fail, because
* we can't allocate from multiple entries.
* With the bitmap free space stealing, we get a single extent entry
* that represents the 1Mb free space, and therefore we're able to
* allocate the whole free space at once.
*/
if (!test_check_exists(cache, SZ_128M - 768 * SZ_1K, SZ_1M)) {
test_msg("Expected region not marked as free\n");
return -ENOENT;
}
if (cache->free_space_ctl->free_space != (SZ_1M + 2 * sectorsize)) {
test_msg("Cache free space is not 1Mb + %u\n", 2 * sectorsize);
return -EINVAL;
}
offset = btrfs_find_space_for_alloc(cache, 0, SZ_1M, 0,
&max_extent_size);
if (offset != (SZ_128M - 768 * SZ_1K)) {
test_msg("Failed to allocate 1Mb from space cache, returned offset is: %llu\n",
offset);
return -EINVAL;
}
/*
* All that remains is 2 * sectorsize free space region
* in a bitmap. Confirm.
*/
ret = check_num_extents_and_bitmaps(cache, 1, 1);
if (ret)
return ret;
if (cache->free_space_ctl->free_space != 2 * sectorsize) {
test_msg("Cache free space is not %u\n", 2 * sectorsize);
return -EINVAL;
}
offset = btrfs_find_space_for_alloc(cache,
0, 2 * sectorsize, 0,
&max_extent_size);
if (offset != SZ_32M) {
test_msg("Failed to allocate %u, offset: %llu\n",
2 * sectorsize,
offset);
return -EINVAL;
}
ret = check_cache_empty(cache);
if (ret)
return ret;
cache->free_space_ctl->op = orig_free_space_ops;
__btrfs_remove_free_space_cache(cache->free_space_ctl);
return 0;
}
int btrfs_test_free_space_cache(u32 sectorsize, u32 nodesize)
{
struct btrfs_fs_info *fs_info;
struct btrfs_block_group_cache *cache;
struct btrfs_root *root = NULL;
int ret = -ENOMEM;
test_msg("Running btrfs free space cache tests\n");
fs_info = btrfs_alloc_dummy_fs_info(nodesize, sectorsize);
if (!fs_info)
return -ENOMEM;
/*
* For ppc64 (with 64k page size), bytes per bitmap might be
* larger than 1G. To make bitmap test available in ppc64,
* alloc dummy block group whose size cross bitmaps.
*/
cache = btrfs_alloc_dummy_block_group(fs_info,
BITS_PER_BITMAP * sectorsize + PAGE_SIZE);
if (!cache) {
test_msg("Couldn't run the tests\n");
btrfs_free_dummy_fs_info(fs_info);
return 0;
}
root = btrfs_alloc_dummy_root(fs_info);
if (IS_ERR(root)) {
ret = PTR_ERR(root);
goto out;
}
root->fs_info->extent_root = root;
ret = test_extents(cache);
if (ret)
goto out;
ret = test_bitmaps(cache, sectorsize);
if (ret)
goto out;
ret = test_bitmaps_and_extents(cache, sectorsize);
if (ret)
goto out;
ret = test_steal_space_from_bitmap_to_extent(cache, sectorsize);
out:
btrfs_free_dummy_block_group(cache);
btrfs_free_dummy_root(root);
btrfs_free_dummy_fs_info(fs_info);
test_msg("Free space cache tests finished\n");
return ret;
}