xfs: ensure that all metadata and data blocks are not cow staging extentsscrub-detect-refcount-gaps_2022-11-09

Make sure that all filesystem metadata blocks and file data blocks are
not also marked as CoW staging extents.  The extra checking added here
was inspired by an actual VM host filesystem corruption incident due to
bugs in the CoW handling of 4.x kernels.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

7 files changed, 39 insertions, 4 deletions

diff --git a/fs/xfs/scrub/agheader.c b/fs/xfs/scrub/agheader.c
index 3dd9151a20ad..520ec054e4a6 100644
--- a/fs/xfs/scrub/agheader.c
+++ b/fs/xfs/scrub/agheader.c
@@ -53,6 +53,7 @@ xchk_superblock_xref(
 	xchk_xref_is_not_inode_chunk(sc, agbno, 1);
 	xchk_xref_is_owned_by(sc, agbno, 1, &XFS_RMAP_OINFO_FS);
 	xchk_xref_is_not_shared(sc, agbno, 1);
+	xchk_xref_is_not_cow_staging(sc, agbno, 1);
 
 	/* scrub teardown will take care of sc->sa for us */
 }
@@ -517,6 +518,7 @@ xchk_agf_xref(
 	xchk_xref_is_owned_by(sc, agbno, 1, &XFS_RMAP_OINFO_FS);
 	xchk_agf_xref_btreeblks(sc);
 	xchk_xref_is_not_shared(sc, agbno, 1);
+	xchk_xref_is_not_cow_staging(sc, agbno, 1);
 	xchk_agf_xref_refcblks(sc);
 
 	/* scrub teardown will take care of sc->sa for us */
@@ -644,6 +646,7 @@ xchk_agfl_block_xref(
 	xchk_xref_is_not_inode_chunk(sc, agbno, 1);
 	xchk_xref_is_owned_by(sc, agbno, 1, &XFS_RMAP_OINFO_AG);
 	xchk_xref_is_not_shared(sc, agbno, 1);
+	xchk_xref_is_not_cow_staging(sc, agbno, 1);
 }
 
 /* Scrub an AGFL block. */
@@ -700,6 +703,7 @@ xchk_agfl_xref(
 	xchk_xref_is_not_inode_chunk(sc, agbno, 1);
 	xchk_xref_is_owned_by(sc, agbno, 1, &XFS_RMAP_OINFO_FS);
 	xchk_xref_is_not_shared(sc, agbno, 1);
+	xchk_xref_is_not_cow_staging(sc, agbno, 1);
 
 	/*
 	 * Scrub teardown will take care of sc->sa for us.  Leave sc->sa
@@ -855,6 +859,7 @@ xchk_agi_xref(
 	xchk_agi_xref_icounts(sc);
 	xchk_xref_is_owned_by(sc, agbno, 1, &XFS_RMAP_OINFO_FS);
 	xchk_xref_is_not_shared(sc, agbno, 1);
+	xchk_xref_is_not_cow_staging(sc, agbno, 1);
 	xchk_agi_xref_fiblocks(sc);
 
 	/* scrub teardown will take care of sc->sa for us */
diff --git a/fs/xfs/scrub/alloc.c b/fs/xfs/scrub/alloc.c
index c72001f6bad9..e9f8d29544aa 100644
--- a/fs/xfs/scrub/alloc.c
+++ b/fs/xfs/scrub/alloc.c
@@ -90,6 +90,7 @@ xchk_allocbt_xref(
 	xchk_xref_is_not_inode_chunk(sc, agbno, len);
 	xchk_xref_has_no_owner(sc, agbno, len);
 	xchk_xref_is_not_shared(sc, agbno, len);
+	xchk_xref_is_not_cow_staging(sc, agbno, len);
 }
 
 /* Scrub a bnobt/cntbt record. */
diff --git a/fs/xfs/scrub/bmap.c b/fs/xfs/scrub/bmap.c
index 575f2c80d055..abc2da0b1824 100644
--- a/fs/xfs/scrub/bmap.c
+++ b/fs/xfs/scrub/bmap.c
@@ -328,12 +328,17 @@ xchk_bmap_iextent_xref(
 	xchk_bmap_xref_rmap(info, irec, agbno);
 	switch (info->whichfork) {
 	case XFS_DATA_FORK:
-		if (xfs_is_reflink_inode(info->sc->ip))
-			break;
-		fallthrough;
+		if (!xfs_is_reflink_inode(info->sc->ip))
+			xchk_xref_is_not_shared(info->sc, agbno,
+					irec->br_blockcount);
+		xchk_xref_is_not_cow_staging(info->sc, agbno,
+				irec->br_blockcount);
+		break;
 	case XFS_ATTR_FORK:
 		xchk_xref_is_not_shared(info->sc, agbno,
 				irec->br_blockcount);
+		xchk_xref_is_not_cow_staging(info->sc, agbno,
+				irec->br_blockcount);
 		break;
 	case XFS_COW_FORK:
 		xchk_xref_is_cow_staging(info->sc, agbno,
diff --git a/fs/xfs/scrub/ialloc.c b/fs/xfs/scrub/ialloc.c
index b85f0cd00bc2..5f04030b86c8 100644
--- a/fs/xfs/scrub/ialloc.c
+++ b/fs/xfs/scrub/ialloc.c
@@ -115,7 +115,7 @@ xchk_iallocbt_chunk(
 		xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
 
 	xchk_iallocbt_chunk_xref(bs->sc, irec, agino, bno, len);
-
+	xchk_xref_is_not_cow_staging(bs->sc, bno, len);
 	return true;
 }
 
diff --git a/fs/xfs/scrub/inode.c b/fs/xfs/scrub/inode.c
index 998bf06d2347..a68ba8684465 100644
--- a/fs/xfs/scrub/inode.c
+++ b/fs/xfs/scrub/inode.c
@@ -558,6 +558,7 @@ xchk_inode_xref(
 	xchk_inode_xref_finobt(sc, ino);
 	xchk_xref_is_owned_by(sc, agbno, 1, &XFS_RMAP_OINFO_INODES);
 	xchk_xref_is_not_shared(sc, agbno, 1);
+	xchk_xref_is_not_cow_staging(sc, agbno, 1);
 	xchk_inode_xref_bmap(sc, dip);
 
 out_free:
diff --git a/fs/xfs/scrub/refcount.c b/fs/xfs/scrub/refcount.c
index 10ef377873f6..e99c1e1246f8 100644
--- a/fs/xfs/scrub/refcount.c
+++ b/fs/xfs/scrub/refcount.c
@@ -555,3 +555,24 @@ xchk_xref_is_not_shared(
 	if (outcome != XBTREE_RECPACKING_EMPTY)
 		xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
 }
+
+/* xref check that the extent is not being used for CoW staging. */
+void
+xchk_xref_is_not_cow_staging(
+	struct xfs_scrub	*sc,
+	xfs_agblock_t		agbno,
+	xfs_extlen_t		len)
+{
+	enum xbtree_recpacking	outcome;
+	int			error;
+
+	if (!sc->sa.refc_cur || xchk_skip_xref(sc->sm))
+		return;
+
+	error = xfs_refcount_has_records(sc->sa.refc_cur, XFS_REFC_DOMAIN_COW,
+			agbno, len, &outcome);
+	if (!xchk_should_check_xref(sc, &error, &sc->sa.refc_cur))
+		return;
+	if (outcome != XBTREE_RECPACKING_EMPTY)
+		xchk_btree_xref_set_corrupt(sc, sc->sa.refc_cur, 0);
+}
diff --git a/fs/xfs/scrub/scrub.h b/fs/xfs/scrub/scrub.h
index 85c055c2ddc5..a331838e22ff 100644
--- a/fs/xfs/scrub/scrub.h
+++ b/fs/xfs/scrub/scrub.h
@@ -166,6 +166,8 @@ void xchk_xref_is_cow_staging(struct xfs_scrub *sc, xfs_agblock_t bno,
 		xfs_extlen_t len);
 void xchk_xref_is_not_shared(struct xfs_scrub *sc, xfs_agblock_t bno,
 		xfs_extlen_t len);
+void xchk_xref_is_not_cow_staging(struct xfs_scrub *sc, xfs_agblock_t bno,
+		xfs_extlen_t len);
 #ifdef CONFIG_XFS_RT
 void xchk_xref_is_used_rt_space(struct xfs_scrub *sc, xfs_rtblock_t rtbno,
 		xfs_extlen_t len);