Btrfs: add helper for em merge logic
This is a prepare work for the following extent map selftest, which
runs tests against em merge logic.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 4ab713b..c6a05ee 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6925,6 +6925,51 @@ static noinline int uncompress_inline(struct btrfs_path *path,
return ret;
}
+int btrfs_add_extent_mapping(struct extent_map_tree *em_tree,
+ struct extent_map **em_in, u64 start, u64 len)
+{
+ int ret;
+ struct extent_map *em = *em_in;
+
+ ret = add_extent_mapping(em_tree, em, 0);
+ /* it is possible that someone inserted the extent into the tree
+ * while we had the lock dropped. It is also possible that
+ * an overlapping map exists in the tree
+ */
+ if (ret == -EEXIST) {
+ struct extent_map *existing;
+
+ ret = 0;
+
+ existing = search_extent_mapping(em_tree, start, len);
+ /*
+ * existing will always be non-NULL, since there must be
+ * extent causing the -EEXIST.
+ */
+ if (start >= existing->start &&
+ start < extent_map_end(existing)) {
+ free_extent_map(em);
+ *em_in = existing;
+ ret = 0;
+ } else {
+ /*
+ * The existing extent map is the one nearest to
+ * the [start, start + len) range which overlaps
+ */
+ ret = merge_extent_mapping(em_tree, existing,
+ em, start);
+ free_extent_map(existing);
+ if (ret) {
+ free_extent_map(em);
+ *em_in = NULL;
+ }
+ }
+ }
+
+ ASSERT(ret == 0 || ret == -EEXIST);
+ return ret;
+}
+
/*
* a bit scary, this does extent mapping from logical file offset to the disk.
* the ugly parts come from merging extents from the disk with the in-ram
@@ -7138,40 +7183,7 @@ struct extent_map *btrfs_get_extent(struct btrfs_inode *inode,
err = 0;
write_lock(&em_tree->lock);
- ret = add_extent_mapping(em_tree, em, 0);
- /* it is possible that someone inserted the extent into the tree
- * while we had the lock dropped. It is also possible that
- * an overlapping map exists in the tree
- */
- if (ret == -EEXIST) {
- struct extent_map *existing;
-
- ret = 0;
-
- existing = search_extent_mapping(em_tree, start, len);
- /*
- * existing will always be non-NULL, since there must be
- * extent causing the -EEXIST.
- */
- if (start >= existing->start &&
- start < extent_map_end(existing)) {
- free_extent_map(em);
- em = existing;
- err = 0;
- } else {
- /*
- * The existing extent map is the one nearest to
- * the [start, start + len) range which overlaps
- */
- err = merge_extent_mapping(em_tree, existing,
- em, start);
- free_extent_map(existing);
- if (err) {
- free_extent_map(em);
- em = NULL;
- }
- }
- }
+ err = btrfs_add_extent_mapping(em_tree, &em, start, len);
write_unlock(&em_tree->lock);
out: