btrfs: btrfs_check_shared should manage its own transaction
Commit afce772e87c3 ("btrfs: fix check_shared for fiemap ioctl") added
transaction semantics around calls to btrfs_check_shared() in order to
provide accurate accounting of delayed refs. The transaction management
should be done inside btrfs_check_shared(), so that callers do not need
to manage transactions individually.
Signed-off-by: Edmund Nadolski <enadolski@suse.com>
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 3725277..35cfa38 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -1580,20 +1580,21 @@ int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
/**
* btrfs_check_shared - tell us whether an extent is shared
*
- * @trans: optional trans handle
- *
* btrfs_check_shared uses the backref walking code but will short
* circuit as soon as it finds a root or inode that doesn't match the
* one passed in. This provides a significant performance benefit for
* callers (such as fiemap) which want to know whether the extent is
* shared but do not need a ref count.
*
+ * This attempts to allocate a transaction in order to account for
+ * delayed refs, but continues on even when the alloc fails.
+ *
* Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
*/
-int btrfs_check_shared(struct btrfs_trans_handle *trans,
- struct btrfs_fs_info *fs_info, u64 root_objectid,
- u64 inum, u64 bytenr)
+int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr)
{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct btrfs_trans_handle *trans;
struct ulist *tmp = NULL;
struct ulist *roots = NULL;
struct ulist_iterator uiter;
@@ -1609,14 +1610,18 @@ int btrfs_check_shared(struct btrfs_trans_handle *trans,
return -ENOMEM;
}
- if (trans)
- btrfs_get_tree_mod_seq(fs_info, &elem);
- else
+ trans = btrfs_join_transaction(root);
+ if (IS_ERR(trans)) {
+ trans = NULL;
down_read(&fs_info->commit_root_sem);
+ } else {
+ btrfs_get_tree_mod_seq(fs_info, &elem);
+ }
+
ULIST_ITER_INIT(&uiter);
while (1) {
ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp,
- roots, NULL, root_objectid, inum, 1);
+ roots, NULL, root->objectid, inum, 1);
if (ret == BACKREF_FOUND_SHARED) {
/* this is the only condition under which we return 1 */
ret = 1;
@@ -1631,10 +1636,13 @@ int btrfs_check_shared(struct btrfs_trans_handle *trans,
bytenr = node->val;
cond_resched();
}
- if (trans)
+
+ if (trans) {
btrfs_put_tree_mod_seq(fs_info, &elem);
- else
+ btrfs_end_transaction(trans);
+ } else {
up_read(&fs_info->commit_root_sem);
+ }
ulist_free(tmp);
ulist_free(roots);
return ret;