The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 1402d17dfd9657be0da8458b2079d03c2d61c86a Mon Sep 17 00:00:00 2001
From: Xiyu Yang xiyuyang19@fudan.edu.cn Date: Mon, 20 Apr 2020 13:39:39 +0800 Subject: [PATCH] btrfs: fix transaction leak in btrfs_recover_relocation
btrfs_recover_relocation() invokes btrfs_join_transaction(), which joins a btrfs_trans_handle object into transactions and returns a reference of it with increased refcount to "trans".
When btrfs_recover_relocation() returns, "trans" becomes invalid, so the refcount should be decreased to keep refcount balanced.
The reference counting issue happens in one exception handling path of btrfs_recover_relocation(). When read_fs_root() failed, the refcnt increased by btrfs_join_transaction() is not decreased, causing a refcnt leak.
Fix this issue by calling btrfs_end_transaction() on this error path when read_fs_root() failed.
Fixes: 79787eaab461 ("btrfs: replace many BUG_ONs with proper error handling") CC: stable@vger.kernel.org # 4.4+ Reviewed-by: Filipe Manana fdmanana@suse.com Signed-off-by: Xiyu Yang xiyuyang19@fudan.edu.cn Signed-off-by: Xin Tan tanxin.ctf@gmail.com Signed-off-by: David Sterba dsterba@suse.com
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index d35936c934ab..03bc7134e8cb 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -4559,6 +4559,7 @@ int btrfs_recover_relocation(struct btrfs_root *root) if (IS_ERR(fs_root)) { err = PTR_ERR(fs_root); list_add_tail(&reloc_root->root_list, &reloc_roots); + btrfs_end_transaction(trans); goto out_unset; }