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-rw-r--r--fs/btrfs/free-space-cache.c140
-rw-r--r--fs/btrfs/tests/free-space-tests.c514
2 files changed, 653 insertions, 1 deletions
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 2f0fe1028e51..33848196550e 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -1997,6 +1997,128 @@ static bool try_merge_free_space(struct btrfs_free_space_ctl *ctl,
return merged;
}
+static bool steal_from_bitmap_to_end(struct btrfs_free_space_ctl *ctl,
+ struct btrfs_free_space *info,
+ bool update_stat)
+{
+ struct btrfs_free_space *bitmap;
+ unsigned long i;
+ unsigned long j;
+ const u64 end = info->offset + info->bytes;
+ const u64 bitmap_offset = offset_to_bitmap(ctl, end);
+ u64 bytes;
+
+ bitmap = tree_search_offset(ctl, bitmap_offset, 1, 0);
+ if (!bitmap)
+ return false;
+
+ i = offset_to_bit(bitmap->offset, ctl->unit, end);
+ j = find_next_zero_bit(bitmap->bitmap, BITS_PER_BITMAP, i);
+ if (j == i)
+ return false;
+ bytes = (j - i) * ctl->unit;
+ info->bytes += bytes;
+
+ if (update_stat)
+ bitmap_clear_bits(ctl, bitmap, end, bytes);
+ else
+ __bitmap_clear_bits(ctl, bitmap, end, bytes);
+
+ if (!bitmap->bytes)
+ free_bitmap(ctl, bitmap);
+
+ return true;
+}
+
+static bool steal_from_bitmap_to_front(struct btrfs_free_space_ctl *ctl,
+ struct btrfs_free_space *info,
+ bool update_stat)
+{
+ struct btrfs_free_space *bitmap;
+ u64 bitmap_offset;
+ unsigned long i;
+ unsigned long j;
+ unsigned long prev_j;
+ u64 bytes;
+
+ bitmap_offset = offset_to_bitmap(ctl, info->offset);
+ /* If we're on a boundary, try the previous logical bitmap. */
+ if (bitmap_offset == info->offset) {
+ if (info->offset == 0)
+ return false;
+ bitmap_offset = offset_to_bitmap(ctl, info->offset - 1);
+ }
+
+ bitmap = tree_search_offset(ctl, bitmap_offset, 1, 0);
+ if (!bitmap)
+ return false;
+
+ i = offset_to_bit(bitmap->offset, ctl->unit, info->offset) - 1;
+ j = 0;
+ prev_j = (unsigned long)-1;
+ for_each_clear_bit_from(j, bitmap->bitmap, BITS_PER_BITMAP) {
+ if (j > i)
+ break;
+ prev_j = j;
+ }
+ if (prev_j == i)
+ return false;
+
+ if (prev_j == (unsigned long)-1)
+ bytes = (i + 1) * ctl->unit;
+ else
+ bytes = (i - prev_j) * ctl->unit;
+
+ info->offset -= bytes;
+ info->bytes += bytes;
+
+ if (update_stat)
+ bitmap_clear_bits(ctl, bitmap, info->offset, bytes);
+ else
+ __bitmap_clear_bits(ctl, bitmap, info->offset, bytes);
+
+ if (!bitmap->bytes)
+ free_bitmap(ctl, bitmap);
+
+ return true;
+}
+
+/*
+ * We prefer always to allocate from extent entries, both for clustered and
+ * non-clustered allocation requests. So when attempting to add a new extent
+ * entry, try to see if there's adjacent free space in bitmap entries, and if
+ * there is, migrate that space from the bitmaps to the extent.
+ * Like this we get better chances of satisfying space allocation requests
+ * because we attempt to satisfy them based on a single cache entry, and never
+ * on 2 or more entries - even if the entries represent a contiguous free space
+ * region (e.g. 1 extent entry + 1 bitmap entry starting where the extent entry
+ * ends).
+ */
+static void steal_from_bitmap(struct btrfs_free_space_ctl *ctl,
+ struct btrfs_free_space *info,
+ bool update_stat)
+{
+ /*
+ * Only work with disconnected entries, as we can change their offset,
+ * and must be extent entries.
+ */
+ ASSERT(!info->bitmap);
+ ASSERT(RB_EMPTY_NODE(&info->offset_index));
+
+ if (ctl->total_bitmaps > 0) {
+ bool stole_end;
+ bool stole_front = false;
+
+ stole_end = steal_from_bitmap_to_end(ctl, info, update_stat);
+ if (ctl->total_bitmaps > 0)
+ stole_front = steal_from_bitmap_to_front(ctl, info,
+ update_stat);
+
+ if (stole_end || stole_front)
+ try_merge_free_space(ctl, info, update_stat);
+ }
+}
+
int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,
u64 offset, u64 bytes)
{
@@ -2009,6 +2131,7 @@ int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,
info->offset = offset;
info->bytes = bytes;
+ RB_CLEAR_NODE(&info->offset_index);
spin_lock(&ctl->tree_lock);
@@ -2028,6 +2151,14 @@ int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,
goto out;
}
link:
+ /*
+ * Only steal free space from adjacent bitmaps if we're sure we're not
+ * going to add the new free space to existing bitmap entries - because
+ * that would mean unnecessary work that would be reverted. Therefore
+ * attempt to steal space from bitmaps if we're adding an extent entry.
+ */
+ steal_from_bitmap(ctl, info, true);
+
ret = link_free_space(ctl, info);
if (ret)
kmem_cache_free(btrfs_free_space_cachep, info);
@@ -2204,10 +2335,13 @@ __btrfs_return_cluster_to_free_space(
entry = rb_entry(node, struct btrfs_free_space, offset_index);
node = rb_next(&entry->offset_index);
rb_erase(&entry->offset_index, &cluster->root);
+ RB_CLEAR_NODE(&entry->offset_index);
bitmap = (entry->bitmap != NULL);
- if (!bitmap)
+ if (!bitmap) {
try_merge_free_space(ctl, entry, false);
+ steal_from_bitmap(ctl, entry, false);
+ }
tree_insert_offset(&ctl->free_space_offset,
entry->offset, &entry->offset_index, bitmap);
}
@@ -3175,6 +3309,7 @@ again:
map = NULL;
add_new_bitmap(ctl, info, offset);
bitmap_info = info;
+ info = NULL;
}
bytes_added = add_bytes_to_bitmap(ctl, bitmap_info, offset, bytes);
@@ -3185,6 +3320,8 @@ again:
if (bytes)
goto again;
+ if (info)
+ kmem_cache_free(btrfs_free_space_cachep, info);
if (map)
kfree(map);
return 0;
@@ -3259,6 +3396,7 @@ have_info:
goto have_info;
}
+ ret = 0;
goto out;
}
diff --git a/fs/btrfs/tests/free-space-tests.c b/fs/btrfs/tests/free-space-tests.c
index c8d9ddf84c69..d78ae10d0446 100644
--- a/fs/btrfs/tests/free-space-tests.c
+++ b/fs/btrfs/tests/free-space-tests.c
@@ -40,6 +40,7 @@ static struct btrfs_block_group_cache *init_test_block_group(void)
cache->key.offset = 1024 * 1024 * 1024;
cache->key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
cache->sectorsize = 4096;
+ cache->full_stripe_len = 4096;
spin_lock_init(&cache->lock);
INIT_LIST_HEAD(&cache->list);
@@ -364,6 +365,517 @@ static int test_bitmaps_and_extents(struct btrfs_block_group_cache *cache)
return 0;
}
+/* Used by test_steal_space_from_bitmap_to_extent(). */
+static bool test_use_bitmap(struct btrfs_free_space_ctl *ctl,
+ struct btrfs_free_space *info)
+{
+ return ctl->free_extents > 0;
+}
+
+/* Used by test_steal_space_from_bitmap_to_extent(). */
+static int
+check_num_extents_and_bitmaps(const struct btrfs_block_group_cache *cache,
+ const int num_extents,
+ const int num_bitmaps)
+{
+ if (cache->free_space_ctl->free_extents != num_extents) {
+ test_msg("Incorrect # of extent entries in the cache: %d, expected %d\n",
+ cache->free_space_ctl->free_extents, num_extents);
+ return -EINVAL;
+ }
+ if (cache->free_space_ctl->total_bitmaps != num_bitmaps) {
+ test_msg("Incorrect # of extent entries in the cache: %d, expected %d\n",
+ cache->free_space_ctl->total_bitmaps, num_bitmaps);
+ return -EINVAL;
+ }
+ return 0;
+}
+
+/* Used by test_steal_space_from_bitmap_to_extent(). */
+static int check_cache_empty(struct btrfs_block_group_cache *cache)
+{
+ u64 offset;
+ u64 max_extent_size;
+
+ /*
+ * Now lets confirm that there's absolutely no free space left to
+ * allocate.
+ */
+ if (cache->free_space_ctl->free_space != 0) {
+ test_msg("Cache free space is not 0\n");
+ return -EINVAL;
+ }
+
+ /* And any allocation request, no matter how small, should fail now. */
+ offset = btrfs_find_space_for_alloc(cache, 0, 4096, 0,
+ &max_extent_size);
+ if (offset != 0) {
+ test_msg("Space allocation did not fail, returned offset: %llu",
+ offset);
+ return -EINVAL;
+ }
+
+ /* And no extent nor bitmap entries in the cache anymore. */
+ return check_num_extents_and_bitmaps(cache, 0, 0);
+}
+
+/*
+ * 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 benefical, 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)
+{
+ int ret;
+ u64 offset;
+ u64 max_extent_size;
+
+ bool (*use_bitmap_op)(struct btrfs_free_space_ctl *,
+ struct btrfs_free_space *);
+
+ 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.
+ */
+ use_bitmap_op = cache->free_space_ctl->op->use_bitmap;
+ cache->free_space_ctl->op->use_bitmap = test_use_bitmap;
+
+ /*
+ * Extent entry covering free space range [128Mb - 256Kb, 128Mb - 128Kb[
+ */
+ ret = test_add_free_space_entry(cache, 128 * 1024 * 1024 - 256 * 1024,
+ 128 * 1024, 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, 128 * 1024 * 1024 + 512 * 1024,
+ 128 * 1024 * 1024 - 512 * 1024, 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,
+ 128 * 1024 * 1024 + 768 * 1024,
+ 128 * 1024 * 1024 - 768 * 1024);
+ 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, 128 * 1024 * 1024 - 256 * 1024,
+ 128 * 1024)) {
+ test_msg("Free space range missing\n");
+ return -ENOENT;
+ }
+ if (!test_check_exists(cache, 128 * 1024 * 1024 + 512 * 1024,
+ 256 * 1024)) {
+ 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, 128 * 1024 * 1024 + 768 * 1024,
+ 128 * 1024 * 1024 - 768 * 1024)) {
+ 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, 128 * 1024 * 1024 + 256 * 1024,
+ 256 * 1024)) {
+ 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, 128 * 1024 * 1024,
+ 256 * 1024)) {
+ 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, 128 * 1024 * 1024, 512 * 1024);
+ 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, 128 * 1024 * 1024, 512 * 1024)) {
+ 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, 128 * 1024 * 1024 + 16 * 1024 * 1024,
+ 4096);
+ 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, 128 * 1024 * 1024 - 128 * 1024,
+ 128 * 1024);
+ 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, 128 * 1024 * 1024 - 128 * 1024,
+ 128 * 1024)) {
+ 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, 128 * 1024 * 1024 - 256 * 1024,
+ 1 * 1024 * 1024)) {
+ test_msg("Expected region not marked as free\n");
+ return -ENOENT;
+ }
+
+ if (cache->free_space_ctl->free_space != (1 * 1024 * 1024 + 4096)) {
+ test_msg("Cache free space is not 1Mb + 4Kb\n");
+ return -EINVAL;
+ }
+
+ offset = btrfs_find_space_for_alloc(cache,
+ 0, 1 * 1024 * 1024, 0,
+ &max_extent_size);
+ if (offset != (128 * 1024 * 1024 - 256 * 1024)) {
+ test_msg("Failed to allocate 1Mb from space cache, returned offset is: %llu\n",
+ offset);
+ return -EINVAL;
+ }
+
+ /* All that remains is a 4Kb 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 != 4096) {
+ test_msg("Cache free space is not 4Kb\n");
+ return -EINVAL;
+ }
+
+ offset = btrfs_find_space_for_alloc(cache,
+ 0, 4096, 0,
+ &max_extent_size);
+ if (offset != (128 * 1024 * 1024 + 16 * 1024 * 1024)) {
+ test_msg("Failed to allocate 4Kb from space cache, returned offset is: %llu\n",
+ 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, 128 * 1024 * 1024 + 128 * 1024,
+ 128 * 1024, 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,
+ 128 * 1024 * 1024 - 512 * 1024, 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,
+ 128 * 1024 * 1024 - 768 * 1024);
+ 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, 128 * 1024 * 1024 + 128 * 1024,
+ 128 * 1024)) {
+ test_msg("Free space range missing\n");
+ return -ENOENT;
+ }
+ if (!test_check_exists(cache, 128 * 1024 * 1024 - 768 * 1024,
+ 256 * 1024)) {
+ 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,
+ 128 * 1024 * 1024 - 768 * 1024)) {
+ 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, 128 * 1024 * 1024 - 512 * 1024,
+ 512 * 1024)) {
+ 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, 128 * 1024 * 1024 - 512 * 1024,
+ 512 * 1024);
+ 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, 128 * 1024 * 1024 - 512 * 1024,
+ 512 * 1024)) {
+ 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, 32 * 1024 * 1024, 8192);
+ 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, 128 * 1024 * 1024, 128 * 1024);
+ 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, 128 * 1024 * 1024, 128 * 1024)) {
+ 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 8Kb 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, 128 * 1024 * 1024 - 768 * 1024,
+ 1 * 1024 * 1024)) {
+ test_msg("Expected region not marked as free\n");
+ return -ENOENT;
+ }
+
+ if (cache->free_space_ctl->free_space != (1 * 1024 * 1024 + 8192)) {
+ test_msg("Cache free space is not 1Mb + 8Kb\n");
+ return -EINVAL;
+ }
+
+ offset = btrfs_find_space_for_alloc(cache,
+ 0, 1 * 1024 * 1024, 0,
+ &max_extent_size);
+ if (offset != (128 * 1024 * 1024 - 768 * 1024)) {
+ test_msg("Failed to allocate 1Mb from space cache, returned offset is: %llu\n",
+ offset);
+ return -EINVAL;
+ }
+
+ /* All that remains is a 8Kb 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 != 8192) {
+ test_msg("Cache free space is not 8Kb\n");
+ return -EINVAL;
+ }
+
+ offset = btrfs_find_space_for_alloc(cache,
+ 0, 8192, 0,
+ &max_extent_size);
+ if (offset != (32 * 1024 * 1024)) {
+ test_msg("Failed to allocate 8Kb from space cache, returned offset is: %llu\n",
+ offset);
+ return -EINVAL;
+ }
+
+ ret = check_cache_empty(cache);
+ if (ret)
+ return ret;
+
+ cache->free_space_ctl->op->use_bitmap = use_bitmap_op;
+ __btrfs_remove_free_space_cache(cache->free_space_ctl);
+
+ return 0;
+}
+
int btrfs_test_free_space_cache(void)
{
struct btrfs_block_group_cache *cache;
@@ -386,6 +898,8 @@ int btrfs_test_free_space_cache(void)
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);
generated by cgit v1.2.3 (git 2.25.1) at 2024-09-30 15:37:23 +0000