The patch below does not apply to the 4.4-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 f6033c5e333238f299c3ae03fac8cc1365b23b77 Mon Sep 17 00:00:00 2001
From: Xiyu Yang xiyuyang19@fudan.edu.cn Date: Tue, 21 Apr 2020 10:54:11 +0800 Subject: [PATCH] btrfs: fix block group leak when removing fails
btrfs_remove_block_group() invokes btrfs_lookup_block_group(), which returns a local reference of the block group that contains the given bytenr to "block_group" with increased refcount.
When btrfs_remove_block_group() returns, "block_group" becomes invalid, so the refcount should be decreased to keep refcount balanced.
The reference counting issue happens in several exception handling paths of btrfs_remove_block_group(). When those error scenarios occur such as btrfs_alloc_path() returns NULL, the function forgets to decrease its refcnt increased by btrfs_lookup_block_group() and will cause a refcnt leak.
Fix this issue by jumping to "out_put_group" label and calling btrfs_put_block_group() when those error scenarios occur.
CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Xiyu Yang xiyuyang19@fudan.edu.cn Signed-off-by: Xin Tan tanxin.ctf@gmail.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c index af9e9a008724..696f47103cfc 100644 --- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -916,7 +916,7 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans, path = btrfs_alloc_path(); if (!path) { ret = -ENOMEM; - goto out; + goto out_put_group; }
/* @@ -954,7 +954,7 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans, ret = btrfs_orphan_add(trans, BTRFS_I(inode)); if (ret) { btrfs_add_delayed_iput(inode); - goto out; + goto out_put_group; } clear_nlink(inode); /* One for the block groups ref */ @@ -977,13 +977,13 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1); if (ret < 0) - goto out; + goto out_put_group; if (ret > 0) btrfs_release_path(path); if (ret == 0) { ret = btrfs_del_item(trans, tree_root, path); if (ret) - goto out; + goto out_put_group; btrfs_release_path(path); }
@@ -1102,9 +1102,9 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
ret = remove_block_group_free_space(trans, block_group); if (ret) - goto out; + goto out_put_group;
- btrfs_put_block_group(block_group); + /* Once for the block groups rbtree */ btrfs_put_block_group(block_group);
ret = btrfs_search_slot(trans, root, &key, path, -1, 1); @@ -1127,6 +1127,10 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans, /* once for the tree */ free_extent_map(em); } + +out_put_group: + /* Once for the lookup reference */ + btrfs_put_block_group(block_group); out: if (remove_rsv) btrfs_delayed_refs_rsv_release(fs_info, 1);