Re: [PATCH] ovl: fix missing upper fs freeze protection on copy up for ioctl

[Vivek Goyal <vgoyal@redhat.com>]

On Tue, Jan 22, 2019 at 07:01:39AM +0200, Amir Goldstein wrote:
> Generalize the helper ovl_open_maybe_copy_up() and use it to copy up
> file with data before FS_IOC_SETFLAGS ioctl.
> 
> Fixes: dab5ca8fd9dd ("ovl: add lsattr/chattr support")
> Cc: <stable@vger.kernel.org> # v4.19
> Signed-off-by: Amir Goldstein <amir73il@gmail.com>

What upper fs freeze protection you are referring to. I am unable to
see it in this new path.

Vivek

> ---
>  fs/overlayfs/copy_up.c   | 6 +++---
>  fs/overlayfs/file.c      | 5 ++---
>  fs/overlayfs/overlayfs.h | 2 +-
>  3 files changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
> index 48119b23375b..0c0e11d529d0 100644
> --- a/fs/overlayfs/copy_up.c
> +++ b/fs/overlayfs/copy_up.c
> @@ -885,14 +885,14 @@ static bool ovl_open_need_copy_up(struct dentry *dentry, int flags)
>  	return true;
>  }
>  
> -int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags)
> +int ovl_maybe_copy_up(struct dentry *dentry, int flags)
>  {
>  	int err = 0;
>  
> -	if (ovl_open_need_copy_up(dentry, file_flags)) {
> +	if (ovl_open_need_copy_up(dentry, flags)) {
>  		err = ovl_want_write(dentry);
>  		if (!err) {
> -			err = ovl_copy_up_flags(dentry, file_flags);
> +			err = ovl_copy_up_flags(dentry, flags);
>  			ovl_drop_write(dentry);
>  		}
>  	}
> diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
> index 84dd957efa24..50e4407398d8 100644
> --- a/fs/overlayfs/file.c
> +++ b/fs/overlayfs/file.c
> @@ -116,11 +116,10 @@ static int ovl_real_fdget(const struct file *file, struct fd *real)
>  
>  static int ovl_open(struct inode *inode, struct file *file)
>  {
> -	struct dentry *dentry = file_dentry(file);
>  	struct file *realfile;
>  	int err;
>  
> -	err = ovl_open_maybe_copy_up(dentry, file->f_flags);
> +	err = ovl_maybe_copy_up(file_dentry(file), file->f_flags);
>  	if (err)
>  		return err;
>  
> @@ -390,7 +389,7 @@ static long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>  		if (ret)
>  			return ret;
>  
> -		ret = ovl_copy_up_with_data(file_dentry(file));
> +		ret = ovl_maybe_copy_up(file_dentry(file), O_WRONLY);
>  		if (!ret) {
>  			ret = ovl_real_ioctl(file, cmd, arg);
>  
> diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
> index 5e45cb3630a0..767eeaf73bf1 100644
> --- a/fs/overlayfs/overlayfs.h
> +++ b/fs/overlayfs/overlayfs.h
> @@ -419,7 +419,7 @@ extern const struct file_operations ovl_file_operations;
>  int ovl_copy_up(struct dentry *dentry);
>  int ovl_copy_up_with_data(struct dentry *dentry);
>  int ovl_copy_up_flags(struct dentry *dentry, int flags);
> -int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags);
> +int ovl_maybe_copy_up(struct dentry *dentry, int flags);
>  int ovl_copy_xattr(struct dentry *old, struct dentry *new);
>  int ovl_set_attr(struct dentry *upper, struct kstat *stat);
>  struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper);
> -- 
> 2.17.1
>