Re: [PATCH 07/14] xfs: Refactor xfs_isilocked()

Darrick J. Wong
2021-06-07T15:49:06Z

On Mon, Jun 07, 2021 at 04:52:17PM +0200, Jan Kara wrote:
> From: Pavel Reichl <preichl@redhat.com>
>
> Refactor xfs_isilocked() to use newly introduced __xfs_rwsem_islocked().
> __xfs_rwsem_islocked() is a helper function which encapsulates checking
> state of rw_semaphores hold by inode.
>
> Signed-off-by: Pavel Reichl <preichl@redhat.com>
> Suggested-by: Dave Chinner <dchinner@redhat.com>
> Suggested-by: Eric Sandeen <sandeen@redhat.com>
> Suggested-by: Darrick J. Wong <darrick.wong@oracle.com>
> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
> fs/xfs/xfs_inode.c | 39 +++++++++++++++++++++++++++++++--------
> fs/xfs/xfs_inode.h | 21 ++++++++++++++-------
> 2 files changed, 45 insertions(+), 15 deletions(-)
>
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 0369eb22c1bb..6247977870bd 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -342,9 +342,34 @@ xfs_ilock_demote(
> }
>
> #if defined(DEBUG) || defined(XFS_WARN)
> -int
> +static inline bool
> +__xfs_rwsem_islocked(
> + struct rw_semaphore *rwsem,
> + int lock_flags,
> + int shift)
> +{
> + lock_flags >>= shift;
> +
> + if (!debug_locks)
> + return rwsem_is_locked(rwsem);
> + /*
> + * If the shared flag is not set, pass 0 to explicitly check for
> + * exclusive access to the lock. If the shared flag is set, we typically
> + * want to make sure the lock is at least held in shared mode
> + * (i.e., shared | excl) but we don't necessarily care that it might
> + * actually be held exclusive. Therefore, pass -1 to check whether the
> + * lock is held in any mode rather than one of the explicit shared mode
> + * values (1 or 2)."

Extra double-quote not needed here.

With that fixed,
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

(You can delete the previous review tag.)

--D

> + */
> + if (lock_flags & (1 << XFS_SHARED_LOCK_SHIFT)) {
> + return lockdep_is_held_type(rwsem, -1);
> + }
> + return lockdep_is_held_type(rwsem, 0);
> +}
> +
> +bool
> xfs_isilocked(
> - xfs_inode_t *ip,
> + struct xfs_inode *ip,
> uint lock_flags)
> {
> if (lock_flags & (XFS_ILOCK_EXCL|XFS_ILOCK_SHARED)) {
> @@ -359,15 +384,13 @@ xfs_isilocked(
> return rwsem_is_locked(&ip->i_mmaplock.mr_lock);
> }
>
> - if (lock_flags & (XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED)) {
> - if (!(lock_flags & XFS_IOLOCK_SHARED))
> - return !debug_locks ||
> - lockdep_is_held_type(&VFS_I(ip)->i_rwsem, 0);
> - return rwsem_is_locked(&VFS_I(ip)->i_rwsem);
> + if (lock_flags & (XFS_IOLOCK_EXCL | XFS_IOLOCK_SHARED)) {
> + return __xfs_rwsem_islocked(&VFS_I(ip)->i_rwsem, lock_flags,
> + XFS_IOLOCK_FLAG_SHIFT);
> }
>
> ASSERT(0);
> - return 0;
> + return false;
> }
> #endif
>
> diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
> index ca826cfba91c..1c0e15c480bc 100644
> --- a/fs/xfs/xfs_inode.h
> +++ b/fs/xfs/xfs_inode.h
> @@ -262,12 +262,19 @@ static inline bool xfs_inode_has_bigtime(struct xfs_inode *ip)
> * Bit ranges: 1<<1 - 1<<16-1 -- iolock/ilock modes (bitfield)
> * 1<<16 - 1<<32-1 -- lockdep annotation (integers)
> */
> -#define XFS_IOLOCK_EXCL (1<<0)
> -#define XFS_IOLOCK_SHARED (1<<1)
> -#define XFS_ILOCK_EXCL (1<<2)
> -#define XFS_ILOCK_SHARED (1<<3)
> -#define XFS_MMAPLOCK_EXCL (1<<4)
> -#define XFS_MMAPLOCK_SHARED (1<<5)
> +
> +#define XFS_IOLOCK_FLAG_SHIFT 0
> +#define XFS_ILOCK_FLAG_SHIFT 2
> +#define XFS_MMAPLOCK_FLAG_SHIFT 4
> +
> +#define XFS_SHARED_LOCK_SHIFT 1
> +
> +#define XFS_IOLOCK_EXCL (1 << XFS_IOLOCK_FLAG_SHIFT)
> +#define XFS_IOLOCK_SHARED (XFS_IOLOCK_EXCL << XFS_SHARED_LOCK_SHIFT)
> +#define XFS_ILOCK_EXCL (1 << XFS_ILOCK_FLAG_SHIFT)
> +#define XFS_ILOCK_SHARED (XFS_ILOCK_EXCL << XFS_SHARED_LOCK_SHIFT)
> +#define XFS_MMAPLOCK_EXCL (1 << XFS_MMAPLOCK_FLAG_SHIFT)
> +#define XFS_MMAPLOCK_SHARED (XFS_MMAPLOCK_EXCL << XFS_SHARED_LOCK_SHIFT)
>
> #define XFS_LOCK_MASK (XFS_IOLOCK_EXCL | XFS_IOLOCK_SHARED \
> | XFS_ILOCK_EXCL | XFS_ILOCK_SHARED \
> @@ -410,7 +417,7 @@ void xfs_ilock(xfs_inode_t *, uint);
> int xfs_ilock_nowait(xfs_inode_t *, uint);
> void xfs_iunlock(xfs_inode_t *, uint);
> void xfs_ilock_demote(xfs_inode_t *, uint);
> -int xfs_isilocked(xfs_inode_t *, uint);
> +bool xfs_isilocked(struct xfs_inode *, uint);
> uint xfs_ilock_data_map_shared(struct xfs_inode *);
> uint xfs_ilock_attr_map_shared(struct xfs_inode *);
>
> --
> 2.26.2
>