2013/12/10 Wang Shilong <wangsl.f...@cn.fujitsu.com>: > On 12/10/2013 12:14 AM, Wang Shilong wrote: >> >> From: Wang Shilong <wangsl.f...@cn.fujitsu.com> >> >> I hit a BUG_ON() when inserting reloc root into >> rc->reloc_root_tree.rb_root, >> the fact is block bytenr has been inserted before, this is really a >> redicious >> bug, the reason is that we freed root node after we have allocated root >> node block,and this block bytenr will be reused and then oops happens. >
By hacking the code (force cow for relocation tree), BUG_ON() can be triggered easily. The problem is that reloc root bytenr inserted into @reloc_root_tree is not within one transaction. root block node can be cowed while it is still in @reloc_root_tree and previous relocation root block can be reused and this oops happen. We can fix it by updating relocation root node in @reloc_root_tree when cowing block, Patch has been make and hopely it can fix this problem, will send v2 later. ^_^ > oops, this is wrong, sorry for noise. Previously, i really made mistakes, free_extent_buffer() even won't free tree block, it just dec refs and free memory if possible. Thanks, Wang > >> >> Signed-off-by: Wang Shilong <wangsl.f...@cn.fujitsu.com> >> --- >> fs/btrfs/relocation.c | 1 - >> 1 file changed, 1 deletion(-) >> >> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c >> index ce459a7..4dc7f26 100644 >> --- a/fs/btrfs/relocation.c >> +++ b/fs/btrfs/relocation.c >> @@ -1361,7 +1361,6 @@ static struct btrfs_root *create_reloc_root(struct >> btrfs_trans_handle *trans, >> } >> btrfs_tree_unlock(eb); >> - free_extent_buffer(eb); >> ret = btrfs_insert_root(trans, root->fs_info->tree_root, >> &root_key, root_item); > > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
