4.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Su Yue <suy.fnst@xxxxxxxxxxxxxx> commit 090a127afa8f73e9618d4058d6755f7ec7453dd6 upstream. In cow_file_range(), create_io_em() may fail, but its return value is not recorded. Then return value may be 0 even it failed which is a wrong behavior. Let cow_file_range() return PTR_ERR(em) if create_io_em() failed. Fixes: 6f9994dbabe5 ("Btrfs: create a helper to create em for IO") CC: stable@xxxxxxxxxxxxxxx # 4.11+ Signed-off-by: Su Yue <suy.fnst@xxxxxxxxxxxxxx> Reviewed-by: Nikolay Borisov <nborisov@xxxxxxxx> Signed-off-by: David Sterba <dsterba@xxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/btrfs/inode.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1018,8 +1018,10 @@ static noinline int cow_file_range(struc ram_size, /* ram_bytes */ BTRFS_COMPRESS_NONE, /* compress_type */ BTRFS_ORDERED_REGULAR /* type */); - if (IS_ERR(em)) + if (IS_ERR(em)) { + ret = PTR_ERR(em); goto out_reserve; + } free_extent_map(em); ret = btrfs_add_ordered_extent(inode, start, ins.objectid,