btrfs-progs: extent-tree: Introduce function to find the first overlapping extent

Introduce a new function, btrfs_search_overlap_extent() to find the first
overlapping extent.

It's useful for later btrfs-convert rework.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/ctree.c b/ctree.c
index 6875bb4..a98ad18 100644 (file)
--- a/ctree.c
+++ b/ctree.c
@@ -2951,3 +2951,27 @@ int btrfs_previous_extent_item(struct btrfs_root *root,
        }
        return 1;
 }
+
+/*
+ * Search in extent tree to found next meta/data extent
+ * Caller needs to check for no-hole or skinny metadata features.
+ */
+int btrfs_next_extent_item(struct btrfs_root *root,
+                       struct btrfs_path *path, u64 max_objectid)
+{
+       struct btrfs_key found_key;
+       int ret;
+
+       while (1) {
+               ret = btrfs_next_item(root, path);
+               if (ret)
+                       return ret;
+               btrfs_item_key_to_cpu(path->nodes[0], &found_key,
+                                     path->slots[0]);
+               if (found_key.objectid > max_objectid)
+                       return 1;
+               if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
+                   found_key.type == BTRFS_METADATA_ITEM_KEY)
+               return 0;
+       }
+}

diff --git a/ctree.h b/ctree.h
index 6943e50..6dfd511 100644 (file)
--- a/ctree.h
+++ b/ctree.h
@@ -2388,6 +2388,8 @@ int btrfs_previous_item(struct btrfs_root *root,
                        int type);
 int btrfs_previous_extent_item(struct btrfs_root *root,
                        struct btrfs_path *path, u64 min_objectid);
+int btrfs_next_extent_item(struct btrfs_root *root,
+                       struct btrfs_path *path, u64 max_objectid);
 int btrfs_cow_block(struct btrfs_trans_handle *trans,
                    struct btrfs_root *root, struct extent_buffer *buf,
                    struct extent_buffer *parent, int parent_slot,

diff --git a/extent-tree.c b/extent-tree.c
index 4a41717..6ccd424 100644 (file)
--- a/extent-tree.c
+++ b/extent-tree.c
@@ -3909,6 +3909,69 @@ int btrfs_fix_block_accounting(struct btrfs_trans_handle *trans,
        return 0;
 }
 
+static void __get_extent_size(struct btrfs_root *root, struct btrfs_path *path,
+                             u64 *start, u64 *len)
+{
+       struct btrfs_key key;
+
+       btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+       BUG_ON(!(key.type == BTRFS_EXTENT_ITEM_KEY ||
+                key.type == BTRFS_METADATA_ITEM_KEY));
+       *start = key.objectid;
+       if (key.type == BTRFS_EXTENT_ITEM_KEY)
+               *len = key.offset;
+       else
+               *len = root->nodesize;
+}
+
+/*
+ * Find first overlap extent for range [bytenr, bytenr + len)
+ * Return 0 for found and point path to it.
+ * Return >0 for not found.
+ * Return <0 for err
+ */
+int btrfs_search_overlap_extent(struct btrfs_root *root,
+                               struct btrfs_path *path, u64 bytenr, u64 len)
+{
+       struct btrfs_key key;
+       u64 cur_start;
+       u64 cur_len;
+       int ret;
+
+       key.objectid = bytenr;
+       key.type = BTRFS_EXTENT_DATA_KEY;
+       key.offset = (u64)-1;
+
+       ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+       if (ret < 0)
+               return ret;
+       BUG_ON(ret == 0);
+
+       ret = btrfs_previous_extent_item(root, path, 0);
+       if (ret < 0)
+               return ret;
+       /* no previous, check next extent */
+       if (ret > 0)
+               goto next;
+       __get_extent_size(root, path, &cur_start, &cur_len);
+       /* Tail overlap */
+       if (cur_start + cur_len > bytenr)
+               return 1;
+
+next:
+       ret = btrfs_next_extent_item(root, path, bytenr + len);
+       if (ret < 0)
+               return ret;
+       /* No next, prev already checked, no overlap */
+       if (ret > 0)
+               return 0;
+       __get_extent_size(root, path, &cur_start, &cur_len);
+       /* head overlap*/
+       if (cur_start < bytenr + len)
+               return 1;
+       return 0;
+}
+
 /*
  * Record a file extent. Do all the required works, such as inserting
  * file extent item, inserting extent item and backref item into extent