Re: [PATCH 1/4] xfs: change xfs_isilocked() to always use lockdep()

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Tue, Jan 28, 2020 at 03:55:25PM +0100, Pavel Reichl wrote:
> mr_writer is obsolete and the information it contains is accesible
> from mr_lock.
> 
> Signed-off-by: Pavel Reichl <preichl@redhat.com>
> ---
>  fs/xfs/xfs_inode.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index c5077e6326c7..32fac6152dc3 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -352,13 +352,17 @@ xfs_isilocked(
>  {
>  	if (lock_flags & (XFS_ILOCK_EXCL|XFS_ILOCK_SHARED)) {
>  		if (!(lock_flags & XFS_ILOCK_SHARED))
> -			return !!ip->i_lock.mr_writer;
> +			return !debug_locks ||
> +				lockdep_is_held_type(&ip->i_lock.mr_lock, 0);

Why do we reference debug_locks here directly?  It looks as though that
variable exists to shut up lockdep assertions WARN_ONs, but
xfs_isilocked is a predicate (and not itself an assertion), so why can't
we 'return lockdep_is_held_type(...);' directly?

(He says scowling at his own RVB in 6552321831dce).

--D

>  		return rwsem_is_locked(&ip->i_lock.mr_lock);
>  	}
>  
>  	if (lock_flags & (XFS_MMAPLOCK_EXCL|XFS_MMAPLOCK_SHARED)) {
>  		if (!(lock_flags & XFS_MMAPLOCK_SHARED))
> -			return !!ip->i_mmaplock.mr_writer;
> +			return !debug_locks ||
> +				lockdep_is_held_type(
> +					&ip->i_mmaplock.mr_lock,
> +					0);
>  		return rwsem_is_locked(&ip->i_mmaplock.mr_lock);
>  	}
>  
> -- 
> 2.24.1
>