xfs: fix xfs_rtalloc_rec units

All the realtime allocation functions deal with space on the rtdev in
units of realtime extents.  However, struct xfs_rtalloc_rec confusingly
uses the word 'block' in the name, even though they're really extents.

Fix the naming problem and fix all the unit handling problems in the two
existing users.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Bill O'Donnell <billodo@redhat.com>
diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c
index 43cfc07..0299feb 100644
--- a/fs/xfs/xfs_fsmap.c
+++ b/fs/xfs/xfs_fsmap.c
@@ -465,10 +465,9 @@ xfs_getfsmap_rtdev_rtbitmap_helper(
 	struct xfs_rmap_irec		irec;
 	xfs_daddr_t			rec_daddr;
 
-	rec_daddr = XFS_FSB_TO_BB(mp, rec->ar_startblock);
-
-	irec.rm_startblock = rec->ar_startblock;
-	irec.rm_blockcount = rec->ar_blockcount;
+	irec.rm_startblock = rec->ar_startext * mp->m_sb.sb_rextsize;
+	rec_daddr = XFS_FSB_TO_BB(mp, irec.rm_startblock);
+	irec.rm_blockcount = rec->ar_extcount * mp->m_sb.sb_rextsize;
 	irec.rm_owner = XFS_RMAP_OWN_NULL;	/* "free" */
 	irec.rm_offset = 0;
 	irec.rm_flags = 0;
@@ -534,8 +533,11 @@ xfs_getfsmap_rtdev_rtbitmap_query(
 
 	xfs_ilock(tp->t_mountp->m_rbmip, XFS_ILOCK_SHARED);
 
-	alow.ar_startblock = info->low.rm_startblock;
-	ahigh.ar_startblock = info->high.rm_startblock;
+	alow.ar_startext = info->low.rm_startblock;
+	ahigh.ar_startext = info->high.rm_startblock;
+	do_div(alow.ar_startext, tp->t_mountp->m_sb.sb_rextsize);
+	if (do_div(ahigh.ar_startext, tp->t_mountp->m_sb.sb_rextsize))
+		ahigh.ar_startext++;
 	error = xfs_rtalloc_query_range(tp, &alow, &ahigh,
 			xfs_getfsmap_rtdev_rtbitmap_helper, info);
 	if (error)