xfs: add a couple of queries to iterate free extents in the rtbitmap

Source kernel commit: fb3c3de2f65c007f3ee50538ea131f5c4603c7bc

Add _query_range and _query_all functions to the realtime bitmap
allocator.  These two functions are similar in usage to the btree
functions with the same name and will be used for getfsmap and scrub.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

2 files changed, 80 insertions, 0 deletions

diff --git a/libxfs/libxfs_priv.h b/libxfs/libxfs_priv.h
index b96fb4659d..0b4c4890b7 100644
--- a/libxfs/libxfs_priv.h
+++ b/libxfs/libxfs_priv.h
@@ -480,6 +480,16 @@ void xfs_verifier_error(struct xfs_buf *bp);
 /* xfs_rtalloc.c */
 int libxfs_rtfree_extent(struct xfs_trans *, xfs_rtblock_t, xfs_extlen_t);
 
+struct xfs_rtalloc_rec {
+	xfs_rtblock_t		ar_startblock;
+	xfs_rtblock_t		ar_blockcount;
+};
+
+typedef int (*xfs_rtalloc_query_range_fn)(
+	struct xfs_trans	*tp,
+	struct xfs_rtalloc_rec	*rec,
+	void			*priv);
+
 int libxfs_zero_extent(struct xfs_inode *ip, xfs_fsblock_t start_fsb,
                         xfs_off_t count_fsb);
 
diff --git a/libxfs/xfs_rtbitmap.c b/libxfs/xfs_rtbitmap.c
index 36fe323b0f..dbd2f8819a 100644
--- a/libxfs/xfs_rtbitmap.c
+++ b/libxfs/xfs_rtbitmap.c
@@ -1011,3 +1011,73 @@ xfs_rtfree_extent(
 	}
 	return 0;
 }
+
+/* Find all the free records within a given range. */
+int
+xfs_rtalloc_query_range(
+	struct xfs_trans		*tp,
+	struct xfs_rtalloc_rec		*low_rec,
+	struct xfs_rtalloc_rec		*high_rec,
+	xfs_rtalloc_query_range_fn	fn,
+	void				*priv)
+{
+	struct xfs_rtalloc_rec		rec;
+	struct xfs_mount		*mp = tp->t_mountp;
+	xfs_rtblock_t			rtstart;
+	xfs_rtblock_t			rtend;
+	xfs_rtblock_t			rem;
+	int				is_free;
+	int				error = 0;
+
+	if (low_rec->ar_startblock > high_rec->ar_startblock)
+		return -EINVAL;
+	else if (low_rec->ar_startblock == high_rec->ar_startblock)
+		return 0;
+
+	/* Iterate the bitmap, looking for discrepancies. */
+	rtstart = low_rec->ar_startblock;
+	rem = high_rec->ar_startblock - rtstart;
+	while (rem) {
+		/* Is the first block free? */
+		error = xfs_rtcheck_range(mp, tp, rtstart, 1, 1, &rtend,
+				&is_free);
+		if (error)
+			break;
+
+		/* How long does the extent go for? */
+		error = xfs_rtfind_forw(mp, tp, rtstart,
+				high_rec->ar_startblock - 1, &rtend);
+		if (error)
+			break;
+
+		if (is_free) {
+			rec.ar_startblock = rtstart;
+			rec.ar_blockcount = rtend - rtstart + 1;
+
+			error = fn(tp, &rec, priv);
+			if (error)
+				break;
+		}
+
+		rem -= rtend - rtstart + 1;
+		rtstart = rtend + 1;
+	}
+
+	return error;
+}
+
+/* Find all the free records. */
+int
+xfs_rtalloc_query_all(
+	struct xfs_trans		*tp,
+	xfs_rtalloc_query_range_fn	fn,
+	void				*priv)
+{
+	struct xfs_rtalloc_rec		keys[2];
+
+	keys[0].ar_startblock = 0;
+	keys[1].ar_startblock = tp->t_mountp->m_sb.sb_rblocks;
+	keys[0].ar_blockcount = keys[1].ar_blockcount = 0;
+
+	return xfs_rtalloc_query_range(tp, &keys[0], &keys[1], fn, priv);
+}