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Diffstat (limited to 'fs/btrfs/extent-tree.c')
-rw-r--r--fs/btrfs/extent-tree.c202
1 files changed, 126 insertions, 76 deletions
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 6290cf41d647..fe1ddbd2bfd6 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -802,70 +802,57 @@ out:
return 0;
}
-u32 btrfs_count_snapshots_in_path(struct btrfs_root *root,
- struct btrfs_path *count_path,
- u64 expected_owner,
- u64 first_extent)
+
+static int get_reference_status(struct btrfs_root *root, u64 bytenr,
+ u64 parent_gen, u64 ref_objectid,
+ u64 *min_generation, u32 *ref_count)
{
struct btrfs_root *extent_root = root->fs_info->extent_root;
struct btrfs_path *path;
- u64 bytenr;
- u64 found_objectid;
- u64 found_owner;
+ struct extent_buffer *leaf;
+ struct btrfs_extent_ref *ref_item;
+ struct btrfs_key key;
+ struct btrfs_key found_key;
u64 root_objectid = root->root_key.objectid;
- u32 total_count = 0;
- u32 extent_refs;
- u32 cur_count;
+ u64 ref_generation;
u32 nritems;
int ret;
- struct btrfs_key key;
- struct btrfs_key found_key;
- struct extent_buffer *l;
- struct btrfs_extent_item *item;
- struct btrfs_extent_ref *ref_item;
- int level = -1;
- /* FIXME, needs locking */
- BUG();
-
- mutex_lock(&root->fs_info->alloc_mutex);
- path = btrfs_alloc_path();
-again:
- if (level == -1)
- bytenr = first_extent;
- else
- bytenr = count_path->nodes[level]->start;
-
- cur_count = 0;
key.objectid = bytenr;
key.offset = 0;
+ key.type = BTRFS_EXTENT_ITEM_KEY;
- btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
+ path = btrfs_alloc_path();
+ mutex_lock(&root->fs_info->alloc_mutex);
ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
if (ret < 0)
goto out;
BUG_ON(ret == 0);
- l = path->nodes[0];
- btrfs_item_key_to_cpu(l, &found_key, path->slots[0]);
+ leaf = path->nodes[0];
+ btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
if (found_key.objectid != bytenr ||
found_key.type != BTRFS_EXTENT_ITEM_KEY) {
+ ret = 1;
goto out;
}
- item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
- extent_refs = btrfs_extent_refs(l, item);
+ *ref_count = 0;
+ *min_generation = (u64)-1;
+
while (1) {
- l = path->nodes[0];
- nritems = btrfs_header_nritems(l);
+ leaf = path->nodes[0];
+ nritems = btrfs_header_nritems(leaf);
if (path->slots[0] >= nritems) {
ret = btrfs_next_leaf(extent_root, path);
+ if (ret < 0)
+ goto out;
if (ret == 0)
continue;
break;
}
- btrfs_item_key_to_cpu(l, &found_key, path->slots[0]);
+ btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
if (found_key.objectid != bytenr)
break;
@@ -874,57 +861,120 @@ again:
continue;
}
- cur_count++;
- ref_item = btrfs_item_ptr(l, path->slots[0],
+ ref_item = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_extent_ref);
- found_objectid = btrfs_ref_root(l, ref_item);
-
- if (found_objectid != root_objectid) {
- total_count = 2;
- goto out;
- }
- if (level == -1) {
- found_owner = btrfs_ref_objectid(l, ref_item);
- if (found_owner != expected_owner) {
- total_count = 2;
- goto out;
- }
- /*
- * nasty. we don't count a reference held by
- * the running transaction. This allows nodatacow
- * to avoid cow most of the time
- */
- if (found_owner >= BTRFS_FIRST_FREE_OBJECTID &&
- btrfs_ref_generation(l, ref_item) ==
- root->fs_info->generation) {
- extent_refs--;
- }
+ ref_generation = btrfs_ref_generation(leaf, ref_item);
+ /*
+ * For (parent_gen > 0 && parent_gen > ref_gen):
+ *
+ * we reach here through the oldest root, therefore
+ * all other reference from same snapshot should have
+ * a larger generation.
+ */
+ if ((root_objectid != btrfs_ref_root(leaf, ref_item)) ||
+ (parent_gen > 0 && parent_gen > ref_generation) ||
+ (ref_objectid >= BTRFS_FIRST_FREE_OBJECTID &&
+ ref_objectid != btrfs_ref_objectid(leaf, ref_item))) {
+ if (ref_count)
+ *ref_count = 2;
+ break;
}
- total_count = 1;
+
+ *ref_count = 1;
+ if (*min_generation > ref_generation)
+ *min_generation = ref_generation;
+
path->slots[0]++;
}
- /*
- * if there is more than one reference against a data extent,
- * we have to assume the other ref is another snapshot
- */
- if (level == -1 && extent_refs > 1) {
- total_count = 2;
+ ret = 0;
+out:
+ mutex_unlock(&root->fs_info->alloc_mutex);
+ btrfs_free_path(path);
+ return ret;
+}
+
+int btrfs_cross_ref_exists(struct btrfs_root *root,
+ struct btrfs_key *key, u64 bytenr)
+{
+ struct btrfs_trans_handle *trans;
+ struct btrfs_root *old_root;
+ struct btrfs_path *path = NULL;
+ struct extent_buffer *eb;
+ struct btrfs_file_extent_item *item;
+ u64 ref_generation;
+ u64 min_generation;
+ u64 extent_start;
+ u32 ref_count;
+ int level;
+ int ret;
+
+ BUG_ON(key->type != BTRFS_EXTENT_DATA_KEY);
+ ret = get_reference_status(root, bytenr, 0, key->objectid,
+ &min_generation, &ref_count);
+ if (ret)
+ return ret;
+
+ if (ref_count != 1)
+ return 1;
+
+ trans = btrfs_start_transaction(root, 0);
+ old_root = root->dirty_root->root;
+ ref_generation = old_root->root_key.offset;
+
+ /* all references are created in running transaction */
+ if (min_generation > ref_generation) {
+ ret = 0;
goto out;
}
- if (cur_count == 0) {
- total_count = 0;
+
+ path = btrfs_alloc_path();
+ if (!path) {
+ ret = -ENOMEM;
goto out;
}
- if (level >= 0 && root->node == count_path->nodes[level])
+
+ path->skip_locking = 1;
+ /* if no item found, the extent is referenced by other snapshot */
+ ret = btrfs_search_slot(NULL, old_root, key, path, 0, 0);
+ if (ret)
goto out;
- level++;
- btrfs_release_path(root, path);
- goto again;
+ eb = path->nodes[0];
+ item = btrfs_item_ptr(eb, path->slots[0],
+ struct btrfs_file_extent_item);
+ if (btrfs_file_extent_type(eb, item) != BTRFS_FILE_EXTENT_REG ||
+ btrfs_file_extent_disk_bytenr(eb, item) != bytenr) {
+ ret = 1;
+ goto out;
+ }
+
+ for (level = BTRFS_MAX_LEVEL - 1; level >= -1; level--) {
+ if (level >= 0) {
+ eb = path->nodes[level];
+ if (!eb)
+ continue;
+ extent_start = eb->start;
+ } else
+ extent_start = bytenr;
+
+ ret = get_reference_status(root, extent_start, ref_generation,
+ 0, &min_generation, &ref_count);
+ if (ret)
+ goto out;
+
+ if (ref_count != 1) {
+ ret = 1;
+ goto out;
+ }
+ if (level >= 0)
+ ref_generation = btrfs_header_generation(eb);
+ }
+ ret = 0;
out:
- btrfs_free_path(path);
- mutex_unlock(&root->fs_info->alloc_mutex);
- return total_count;
+ if (path)
+ btrfs_free_path(path);
+ btrfs_end_transaction(trans, root);
+ return ret;
}
int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-28 02:59:13 +0000