Re: [PATCH v7 11/17] locks: report l_pid as -1 for FL_FILE_PVT locks

["J. Bruce Fields" <bfields@fieldses.org>]

On Wed, Mar 19, 2014 at 04:45:55PM -0400, Jeff Layton wrote:
> FL_FILE_PVT locks are no longer tied to a particular pid, and are
> instead inheritable by child processes. Report a l_pid of '-1' for
> these sorts of locks since the pid is somewhat meaningless for them.
> 
> This precedent comes from FreeBSD. There, POSIX and flock() locks can
> conflict with one another. If fcntl(F_GETLK, ...) returns a lock set
> with flock() then the l_pid member cannot be a process ID because the
> lock is not held by a process as such.

ACK.--b.

> 
> Signed-off-by: Jeff Layton <jlayton@redhat.com>
> ---
>  fs/locks.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/locks.c b/fs/locks.c
> index f1b9b149dd39..5953b2cdef9c 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -1864,7 +1864,7 @@ EXPORT_SYMBOL_GPL(vfs_test_lock);
>  
>  static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
>  {
> -	flock->l_pid = fl->fl_pid;
> +	flock->l_pid = IS_FILE_PVT(fl) ? -1 : fl->fl_pid;
>  #if BITS_PER_LONG == 32
>  	/*
>  	 * Make sure we can represent the posix lock via
> @@ -1886,7 +1886,7 @@ static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
>  #if BITS_PER_LONG == 32
>  static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
>  {
> -	flock->l_pid = fl->fl_pid;
> +	flock->l_pid = IS_FILE_PVT(fl) ? -1 : fl->fl_pid;
>  	flock->l_start = fl->fl_start;
>  	flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
>  		fl->fl_end - fl->fl_start + 1;
> -- 
> 1.8.5.3
>