[PATCH v7 1/4] xfs: Refactor xfs_isilocked()

[Pavel Reichl <preichl@xxxxxxxxxx>]

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@xxxxxxxxxx>
Suggested-by: Dave Chinner <dchinner@xxxxxxxxxx>
Suggested-by: Eric Sandeen <sandeen@xxxxxxxxxx>
Suggested-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
Changes from V6:
	* __xfs_rwsem_islocked() takes flags param
	* changed logic of __xfs_rwsem_islocked() so that
	holding a rwsem writte-locked implies read access as wel 

 fs/xfs/xfs_inode.c | 62 ++++++++++++++++++++++++++++++++++------------
 fs/xfs/xfs_inode.h | 21 ++++++++++------
 2 files changed, 60 insertions(+), 23 deletions(-)

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index c5077e6326c7..db356f815adc 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -345,32 +345,62 @@ xfs_ilock_demote(
 }
 
 #if defined(DEBUG) || defined(XFS_WARN)
-int
+static inline bool
+__xfs_rwsem_islocked(
+	struct rw_semaphore	*rwsem,
+	int			lock_flags)
+{
+	int	arg;
+
+	if (!debug_locks)
+		return rwsem_is_locked(rwsem);
+
+	if (lock_flags & (1 << XFS_SHARED_LOCK_SHIFT)) {
+		/*
+		 * The caller could be asking if we have (shared | excl)
+		 * access to the lock. Ask lockdep if the rwsem is
+		 * locked either for read or write access.
+		 *
+		 * The caller could also be asking if we have only
+		 * shared access to the lock. Holding a rwsem
+		 * write-locked implies read access as well, so the
+		 * request to lockdep is the same for this case.
+		 */
+		arg = -1;
+	} else {
+		/*
+		 * The caller is asking if we have only exclusive access
+		 * to the lock. Ask lockdep if the rwsem is locked for
+		 * write access.
+		 */
+		arg = 0;
+	}
+
+	return lockdep_is_held_type(rwsem, arg);
+}
+
+bool
 xfs_isilocked(
-	xfs_inode_t		*ip,
+	struct xfs_inode	*ip,
 	uint			lock_flags)
 {
-	if (lock_flags & (XFS_ILOCK_EXCL|XFS_ILOCK_SHARED)) {
-		if (!(lock_flags & XFS_ILOCK_SHARED))
-			return !!ip->i_lock.mr_writer;
-		return rwsem_is_locked(&ip->i_lock.mr_lock);
+	if (lock_flags & (XFS_ILOCK_EXCL | XFS_ILOCK_SHARED)) {
+		return __xfs_rwsem_islocked(&ip->i_lock,
+				(lock_flags >> XFS_ILOCK_FLAG_SHIFT));
 	}
 
-	if (lock_flags & (XFS_MMAPLOCK_EXCL|XFS_MMAPLOCK_SHARED)) {
-		if (!(lock_flags & XFS_MMAPLOCK_SHARED))
-			return !!ip->i_mmaplock.mr_writer;
-		return rwsem_is_locked(&ip->i_mmaplock.mr_lock);
+	if (lock_flags & (XFS_MMAPLOCK_EXCL | XFS_MMAPLOCK_SHARED)) {
+		return __xfs_rwsem_islocked(&ip->i_mmaplock,
+				(lock_flags >> XFS_MMAPLOCK_FLAG_SHIFT));
 	}
 
-	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 492e53992fa9..8df2c9e1a34e 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -272,12 +272,19 @@ static inline void xfs_ifunlock(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 \
@@ -416,7 +423,7 @@ 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(xfs_inode_t *, uint);
 uint		xfs_ilock_data_map_shared(struct xfs_inode *);
 uint		xfs_ilock_attr_map_shared(struct xfs_inode *);
 
-- 
2.25.1