Merge tag 'realtime-groups-6.13_2024-11-05' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into staging-merge

xfs: shard the realtime section [v5.5 06/10]

Right now, the realtime section uses a single pair of metadata inodes to
store the free space information.  This presents a scalability problem
since every thread trying to allocate or free rt extents have to lock
these files.  Solve this problem by sharding the realtime section into
separate realtime allocation groups.

While we're at it, define a superblock to be stamped into the start of
the rt section.  This enables utilities such as blkid to identify block
devices containing realtime sections, and avoids the situation where
anything written into block 0 of the realtime extent can be
misinterpreted as file data.

The best advantage for rtgroups will become evident later when we get to
adding rmap and reflink to the realtime volume, since the geometry
constraints are the same for rt groups and AGs.  Hence we can reuse all
that code directly.

This is a very large patchset, but it catches us up with 20 years of
technical debt that have accumulated.

With a bit of luck, this should all go splendidly.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>

1 files changed, 15 insertions, 1 deletions

diff --git a/fs/xfs/scrub/bmap.c b/fs/xfs/scrub/bmap.c
index 008630b2b752..7e00312225ed 100644
--- a/fs/xfs/scrub/bmap.c
+++ b/fs/xfs/scrub/bmap.c
@@ -834,9 +834,12 @@ xchk_bmap_iext_mapping(
 /* Are these two mappings contiguous with each other? */
 static inline bool
 xchk_are_bmaps_contiguous(
+	const struct xchk_bmap_info	*info,
 	const struct xfs_bmbt_irec	*b1,
 	const struct xfs_bmbt_irec	*b2)
 {
+	struct xfs_mount		*mp = info->sc->mp;
+
 	/* Don't try to combine unallocated mappings. */
 	if (!xfs_bmap_is_real_extent(b1))
 		return false;
@@ -850,6 +853,17 @@ xchk_are_bmaps_contiguous(
 		return false;
 	if (b1->br_state != b2->br_state)
 		return false;
+
+	/*
+	 * Don't combine bmaps that would cross rtgroup boundaries.  This is a
+	 * valid state, but if combined they will fail rtb extent checks.
+	 */
+	if (info->is_rt && xfs_has_rtgroups(mp)) {
+		if (xfs_rtb_to_rgno(mp, b1->br_startblock) !=
+		    xfs_rtb_to_rgno(mp, b2->br_startblock))
+			return false;
+	}
+
 	return true;
 }
 
@@ -887,7 +901,7 @@ xchk_bmap_iext_iter(
 	 * that we just read, if possible.
 	 */
 	while (xfs_iext_peek_next_extent(ifp, &info->icur, &got)) {
-		if (!xchk_are_bmaps_contiguous(irec, &got))
+		if (!xchk_are_bmaps_contiguous(info, irec, &got))
 			break;
 
 		if (!xchk_bmap_iext_mapping(info, &got)) {