xfs: Convert double locking of MMAPLOCK to use VFS helpers

Convert places in XFS that take MMAPLOCK for two inodes to use helper
VFS provides for it (filemap_invalidate_down_write_two()). Note that
this changes lock ordering for MMAPLOCK from inode number based ordering
to pointer based ordering VFS generally uses.

CC: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/xfs/xfs_bmap_util.c

@@ -1626,7 +1626,6 @@ xfs_swap_extents(
 	struct xfs_bstat	*sbp = &sxp->sx_stat;
 	int			src_log_flags, target_log_flags;
 	int			error = 0;
-	int			lock_flags;
 	uint64_t		f;
 	int			resblks = 0;
 	unsigned int		flags = 0;
@@ -1638,8 +1637,8 @@ xfs_swap_extents(
 	 * do the rest of the checks.
 	 */
 	lock_two_nondirectories(VFS_I(ip), VFS_I(tip));
-	lock_flags = XFS_MMAPLOCK_EXCL;
-	xfs_lock_two_inodes(ip, XFS_MMAPLOCK_EXCL, tip, XFS_MMAPLOCK_EXCL);
+	filemap_invalidate_lock_two(VFS_I(ip)->i_mapping,
+				    VFS_I(tip)->i_mapping);
 
 	/* Verify that both files have the same format */
 	if ((VFS_I(ip)->i_mode & S_IFMT) != (VFS_I(tip)->i_mode & S_IFMT)) {
@@ -1711,7 +1710,6 @@ xfs_swap_extents(
 	 * or cancel will unlock the inodes from this point onwards.
 	 */
 	xfs_lock_two_inodes(ip, XFS_ILOCK_EXCL, tip, XFS_ILOCK_EXCL);
-	lock_flags |= XFS_ILOCK_EXCL;
 	xfs_trans_ijoin(tp, ip, 0);
 	xfs_trans_ijoin(tp, tip, 0);
 
@@ -1830,13 +1828,16 @@ xfs_swap_extents(
 	trace_xfs_swap_extent_after(ip, 0);
 	trace_xfs_swap_extent_after(tip, 1);
 
+out_unlock_ilock:
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+	xfs_iunlock(tip, XFS_ILOCK_EXCL);
 out_unlock:
-	xfs_iunlock(ip, lock_flags);
-	xfs_iunlock(tip, lock_flags);
+	filemap_invalidate_unlock_two(VFS_I(ip)->i_mapping,
+				      VFS_I(tip)->i_mapping);
 	unlock_two_nondirectories(VFS_I(ip), VFS_I(tip));
 	return error;
 
 out_trans_cancel:
 	xfs_trans_cancel(tp);
-	goto out_unlock;
+	goto out_unlock_ilock;
 }

fs/xfs/xfs_inode.c

@@ -552,12 +552,10 @@ xfs_lock_inodes(
 }
 
 /*
- * xfs_lock_two_inodes() can only be used to lock one type of lock at a time -
- * the mmaplock or the ilock, but not more than one type at a time. If we lock
- * more than one at a time, lockdep will report false positives saying we have
- * violated locking orders.  The iolock must be double-locked separately since
- * we use i_rwsem for that.  We now support taking one lock EXCL and the other
- * SHARED.
+ * xfs_lock_two_inodes() can only be used to lock ilock. The iolock and
+ * mmaplock must be double-locked separately since we use i_rwsem and
+ * invalidate_lock for that. We now support taking one lock EXCL and the
+ * other SHARED.
  */
 void
 xfs_lock_two_inodes(
@@ -575,15 +573,8 @@ xfs_lock_two_inodes(
 	ASSERT(hweight32(ip1_mode) == 1);
 	ASSERT(!(ip0_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)));
 	ASSERT(!(ip1_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)));
-	ASSERT(!(ip0_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) ||
-	       !(ip0_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
-	ASSERT(!(ip1_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) ||
-	       !(ip1_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
-	ASSERT(!(ip1_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) ||
-	       !(ip0_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
-	ASSERT(!(ip0_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) ||
-	       !(ip1_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
-
+	ASSERT(!(ip0_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)));
+	ASSERT(!(ip1_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)));
 	ASSERT(ip0->i_ino != ip1->i_ino);
 
 	if (ip0->i_ino > ip1->i_ino) {
@@ -3748,11 +3739,8 @@ xfs_ilock2_io_mmap(
 	ret = xfs_iolock_two_inodes_and_break_layout(VFS_I(ip1), VFS_I(ip2));
 	if (ret)
 		return ret;
-	if (ip1 == ip2)
-		xfs_ilock(ip1, XFS_MMAPLOCK_EXCL);
-	else
-		xfs_lock_two_inodes(ip1, XFS_MMAPLOCK_EXCL,
-				    ip2, XFS_MMAPLOCK_EXCL);
+	filemap_invalidate_lock_two(VFS_I(ip1)->i_mapping,
+				    VFS_I(ip2)->i_mapping);
 	return 0;
 }
 
@@ -3762,12 +3750,9 @@ xfs_iunlock2_io_mmap(
 	struct xfs_inode	*ip1,
 	struct xfs_inode	*ip2)
 {
-	bool			same_inode = (ip1 == ip2);
-
-	xfs_iunlock(ip2, XFS_MMAPLOCK_EXCL);
-	if (!same_inode)
-		xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL);
+	filemap_invalidate_unlock_two(VFS_I(ip1)->i_mapping,
+				      VFS_I(ip2)->i_mapping);
 	inode_unlock(VFS_I(ip2));
-	if (!same_inode)
+	if (ip1 != ip2)
 		inode_unlock(VFS_I(ip1));
 }