xfs: enable fsmap reporting for internal RT devices

File system with internal RT devices are a bit odd in that we need
to report AGs and RGs.  To make this happen use separate synthetic
fmr_device values for the different sections instead of the dev_t
mapping used by other XFS configurations.

The data device is reported as file system metadata before the
start of the RGs for the synthetic RT fmr_device.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

fs/xfs/libxfs/xfs_fs.h

@@ -1082,6 +1082,15 @@ struct xfs_rtgroup_geometry {
 #define XFS_IOC_COMMIT_RANGE	     _IOW ('X', 131, struct xfs_commit_range)
 /*	XFS_IOC_GETFSUUID ---------- deprecated 140	 */
 
+/*
+ * Devices supported by a single XFS file system.  Reported in fsmaps fmr_device
+ * when using internal RT devices.
+ */
+enum xfs_device {
+	XFS_DEV_DATA	= 1,
+	XFS_DEV_LOG	= 2,
+	XFS_DEV_RT	= 3,
+};
 
 #ifndef HAVE_BBMACROS
 /*

fs/xfs/xfs_fsmap.c

@@ -879,17 +879,39 @@ xfs_getfsmap_rtdev_rmapbt(
 	struct xfs_mount		*mp = tp->t_mountp;
 	struct xfs_rtgroup		*rtg = NULL;
 	struct xfs_btree_cur		*bt_cur = NULL;
+	xfs_daddr_t			rtstart_daddr;
 	xfs_rtblock_t			start_rtb;
 	xfs_rtblock_t			end_rtb;
 	xfs_rgnumber_t			start_rg, end_rg;
 	uint64_t			eofs;
 	int				error = 0;
 
-	eofs = XFS_FSB_TO_BB(mp, mp->m_sb.sb_rblocks);
+	eofs = XFS_FSB_TO_BB(mp, mp->m_sb.sb_rtstart + mp->m_sb.sb_rblocks);
 	if (keys[0].fmr_physical >= eofs)
 		return 0;
-	start_rtb = xfs_daddr_to_rtb(mp, keys[0].fmr_physical);
+
-	end_rtb = xfs_daddr_to_rtb(mp, min(eofs - 1, keys[1].fmr_physical));
+	rtstart_daddr = XFS_FSB_TO_BB(mp, mp->m_sb.sb_rtstart);
+	if (keys[0].fmr_physical < rtstart_daddr) {
+		struct xfs_fsmap_irec		frec = {
+			.owner			= XFS_RMAP_OWN_FS,
+			.len_daddr		= rtstart_daddr,
+		};
+
+		/* Adjust the low key if we are continuing from where we left off. */
+		if (keys[0].fmr_length > 0) {
+			info->low_daddr = keys[0].fmr_physical + keys[0].fmr_length;
+			return 0;
+		}
+
+		/* Fabricate an rmap entry for space occupied by the data dev */
+		error = xfs_getfsmap_helper(tp, info, &frec);
+		if (error)
+			return error;
+	}
+
+	start_rtb = xfs_daddr_to_rtb(mp, rtstart_daddr + keys[0].fmr_physical);
+	end_rtb = xfs_daddr_to_rtb(mp, rtstart_daddr +
+			min(eofs - 1, keys[1].fmr_physical));
 
 	info->missing_owner = XFS_FMR_OWN_FREE;
 
@@ -1004,22 +1026,40 @@ xfs_getfsmap_rtdev_rmapbt(
 }
 #endif /* CONFIG_XFS_RT */
 
+static uint32_t
+xfs_getfsmap_device(
+	struct xfs_mount	*mp,
+	enum xfs_device		dev)
+{
+	if (mp->m_sb.sb_rtstart)
+		return dev;
+
+	switch (dev) {
+	case XFS_DEV_DATA:
+		return new_encode_dev(mp->m_ddev_targp->bt_dev);
+	case XFS_DEV_LOG:
+		return new_encode_dev(mp->m_logdev_targp->bt_dev);
+	case XFS_DEV_RT:
+		if (!mp->m_rtdev_targp)
+			break;
+		return new_encode_dev(mp->m_rtdev_targp->bt_dev);
+	}
+
+	return -1;
+}
+
 /* Do we recognize the device? */
 STATIC bool
 xfs_getfsmap_is_valid_device(
 	struct xfs_mount	*mp,
 	struct xfs_fsmap	*fm)
 {
-	if (fm->fmr_device == 0 || fm->fmr_device == UINT_MAX ||
+	return fm->fmr_device == 0 ||
-	    fm->fmr_device == new_encode_dev(mp->m_ddev_targp->bt_dev))
+		fm->fmr_device == UINT_MAX ||
-		return true;
+		fm->fmr_device == xfs_getfsmap_device(mp, XFS_DEV_DATA) ||
-	if (mp->m_logdev_targp &&
+		fm->fmr_device == xfs_getfsmap_device(mp, XFS_DEV_LOG) ||
-	    fm->fmr_device == new_encode_dev(mp->m_logdev_targp->bt_dev))
+		(mp->m_rtdev_targp &&
-		return true;
+		 fm->fmr_device == xfs_getfsmap_device(mp, XFS_DEV_RT));
-	if (mp->m_rtdev_targp &&
-	    fm->fmr_device == new_encode_dev(mp->m_rtdev_targp->bt_dev))
-		return true;
-	return false;
 }
 
 /* Ensure that the low key is less than the high key. */
@@ -1126,7 +1166,7 @@ xfs_getfsmap(
 	/* Set up our device handlers. */
 	memset(handlers, 0, sizeof(handlers));
 	handlers[0].nr_sectors = XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks);
-	handlers[0].dev = new_encode_dev(mp->m_ddev_targp->bt_dev);
+	handlers[0].dev = xfs_getfsmap_device(mp, XFS_DEV_DATA);
 	if (use_rmap)
 		handlers[0].fn = xfs_getfsmap_datadev_rmapbt;
 	else
@@ -1134,7 +1174,7 @@ xfs_getfsmap(
 	if (mp->m_logdev_targp != mp->m_ddev_targp) {
 		handlers[1].nr_sectors = XFS_FSB_TO_BB(mp,
 						       mp->m_sb.sb_logblocks);
-		handlers[1].dev = new_encode_dev(mp->m_logdev_targp->bt_dev);
+		handlers[1].dev = xfs_getfsmap_device(mp, XFS_DEV_LOG);
 		handlers[1].fn = xfs_getfsmap_logdev;
 	}
 #ifdef CONFIG_XFS_RT
@@ -1144,7 +1184,7 @@ xfs_getfsmap(
 	 */
 	if (mp->m_rtdev_targp && (use_rmap || !xfs_has_zoned(mp))) {
 		handlers[2].nr_sectors = XFS_FSB_TO_BB(mp, mp->m_sb.sb_rblocks);
-		handlers[2].dev = new_encode_dev(mp->m_rtdev_targp->bt_dev);
+		handlers[2].dev = xfs_getfsmap_device(mp, XFS_DEV_RT);
 		if (use_rmap)
 			handlers[2].fn = xfs_getfsmap_rtdev_rmapbt;
 		else
@@ -1234,6 +1274,12 @@ xfs_getfsmap(
 
 	if (tp)
 		xfs_trans_cancel(tp);
+
+	/*
+	 * For internal RT device we need to report different synthetic devices
+	 * for a single physical device, and thus can't report the actual dev_t.
+	 */
+	if (!mp->m_sb.sb_rtstart)
 		head->fmh_oflags = FMH_OF_DEV_T;
 	return error;
 }