Excluding or pining all metadata blocks is not time-efficient for large
storage filesystems.
Here is another way to mark all metadata block groups full and allocate
a new chunk for CoW. So new reservered extents never overwrite
extents.
Introduce modify_block_groups_cache() to modify all blocks groups
cache state and set all extents in block groups unfree in free space
cache.
mark/clear_block_groups_full() wraps above function.
Suggested-by: Qu Wenruo <w...@suse.com>
Signed-off-by: Su Yue <suy.f...@cn.fujitsu.com>
---
check/mode-lowmem.c | 93 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 93 insertions(+)
diff --git a/check/mode-lowmem.c b/check/mode-lowmem.c
index 1fc84f1e8c44..a200c28a9cf7 100644
--- a/check/mode-lowmem.c
+++ b/check/mode-lowmem.c
@@ -233,6 +233,99 @@ static int update_nodes_refs(struct btrfs_root *root, u64
bytenr,
return 0;
}
+/*
+ * Mark all extents unfree in the block group. And set @block_group->cached
+ * according to @cache.
+ */
+static int modify_block_group_cache(struct btrfs_fs_info *fs_info,
+ struct btrfs_block_group_cache *block_group, int cache)
+{
+ struct extent_io_tree *free_space_cache = &fs_info->free_space_cache;
+ u64 start = block_group->key.objectid;
+ u64 end = start + block_group->key.offset;
+
+ if (cache && !block_group->cached) {
+ block_group->cached = 1;
+ clear_extent_dirty(free_space_cache, start, end - 1);
+ }
+
+ if (!cache && block_group->cached) {
+ block_group->cached = 0;
+ clear_extent_dirty(free_space_cache, start, end - 1);
+ }
+ return 0;
+}
+
+/*
+ * Modify block groups which have @flags unfree in free space cache.
+ *
+ * @cache: if 0, clear block groups cache state;
+ * not 0, mark blocks groups cached.
+ */
+static int modify_block_groups_cache(struct btrfs_fs_info *fs_info, u64 flags,
+ int cache)
+{
+ struct btrfs_root *root = fs_info->extent_root;
+ struct btrfs_key key;
+ struct btrfs_path path;
+ struct btrfs_block_group_cache *bg_cache;
+ struct btrfs_block_group_item *bi;
+ struct btrfs_block_group_item bg_item;
+ struct extent_buffer *eb;
+ int slot;
+ int ret;
+
+ key.objectid = 0;
+ key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
+ key.offset = 0;
+
+ btrfs_init_path(&path);
+ ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
+ if (ret < 0) {
+ error("fail to search block groups due to %s", strerror(-ret));
+ goto out;
+ }
+
+ while (1) {
+ eb = path.nodes[0];
+ slot = path.slots[0];
+ btrfs_item_key_to_cpu(eb, &key, slot);
+ bg_cache = btrfs_lookup_block_group(fs_info, key.objectid);
+ if (!bg_cache) {
+ ret = -ENOENT;
+ goto out;
+ }
+
+ bi = btrfs_item_ptr(eb, slot, struct btrfs_block_group_item);
+ read_extent_buffer(eb, &bg_item, (unsigned long)bi,
+ sizeof(bg_item));
+ if (btrfs_block_group_flags(&bg_item) & flags)
+ modify_block_group_cache(fs_info, bg_cache, cache);
+
+ ret = btrfs_next_item(root, &path);
+ if (ret > 0) {
+ ret = 0;
+ goto out;
+ }
+ if (ret < 0)
+ goto out;
+ }
+
+out:
+ btrfs_release_path(&path);
+ return ret;
+}
+
+static int mark_block_groups_full(struct btrfs_fs_info *fs_info, u64 flags)
+{
+ return modify_block_groups_cache(fs_info, flags, 1);
+}
+
+static int clear_block_groups_full(struct btrfs_fs_info *fs_info, u64 flags)
+{
+ return modify_block_groups_cache(fs_info, flags, 0);
+}
+
/*
* This function only handles BACKREF_MISSING,
* If corresponding extent item exists, increase the ref, else insert an extent
--
2.16.1
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