[PATCH V2] xfs: don't treat unknown di_flags2 as corruption in scrub

[Eric Sandeen <sandeen@sandeen.net>]

xchk_inode_flags2() currently treats any di_flags2 values that the
running kernel doesn't recognize as corruption, and calls
xchk_ino_set_corrupt() if they are set.  However, it's entirely possible
that these flags were set in some newer kernel and are quite valid,
but ignored in this kernel.

(Validators don't care one bit about unknown di_flags2.)

Call xchk_ino_set_warning instead, because this may or may not actually
indicate a problem.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---

V2: continue to treat unknown di_flag value as corruption, and add
    comments about how the last di_flag bit cannot be used.

diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index 059bc44c27e8..afbe336600e1 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -1016,6 +1016,8 @@ static inline void xfs_dinode_put_rdev(struct xfs_dinode *dip, xfs_dev_t rdev)
 #define XFS_DIFLAG_EXTSZINHERIT_BIT 12	/* inherit inode extent size */
 #define XFS_DIFLAG_NODEFRAG_BIT     13	/* do not reorganize/defragment */
 #define XFS_DIFLAG_FILESTREAM_BIT   14  /* use filestream allocator */
+/* Do not use bit 15, di_flags is legacy and unchanging now */
+
 #define XFS_DIFLAG_REALTIME      (1 << XFS_DIFLAG_REALTIME_BIT)
 #define XFS_DIFLAG_PREALLOC      (1 << XFS_DIFLAG_PREALLOC_BIT)
 #define XFS_DIFLAG_NEWRTBM       (1 << XFS_DIFLAG_NEWRTBM_BIT)
diff --git a/fs/xfs/scrub/inode.c b/fs/xfs/scrub/inode.c
index 5b3b177c0fc9..8fb29540af45 100644
--- a/fs/xfs/scrub/inode.c
+++ b/fs/xfs/scrub/inode.c
@@ -126,6 +126,7 @@ xchk_inode_flags(
 {
 	struct xfs_mount	*mp = sc->mp;
 
+	/* di_flags are all taken, last bit cannot be used */
 	if (flags & ~XFS_DIFLAG_ANY)
 		goto bad;
 
@@ -172,8 +173,9 @@ xchk_inode_flags2(
 {
 	struct xfs_mount	*mp = sc->mp;
 
+	/* Unknown di_flags2 could be from a future kernel */
 	if (flags2 & ~XFS_DIFLAG2_ANY)
-		goto bad;
+		xchk_ino_set_warning(sc, ino);
 
 	/* reflink flag requires reflink feature */
 	if ((flags2 & XFS_DIFLAG2_REFLINK) &&