xfs: warn about inodes with project id of -1

Inodes aren't supposed to have a project id of -1U (aka 4294967295) but
the kernel hasn't always validated FSSETXATTR correctly.  Flag this as
something for the sysadmin to check out.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/scrub/inode.c

@@ -233,6 +233,7 @@ xchk_dinode(
 	unsigned long long	isize;
 	uint64_t		flags2;
 	uint32_t		nextents;
+	prid_t			prid;
 	uint16_t		flags;
 	uint16_t		mode;
 
@@ -267,6 +268,7 @@ xchk_dinode(
 		 * so just mark this inode for preening.
 		 */
 		xchk_ino_set_preen(sc, ino);
+		prid = 0;
 		break;
 	case 2:
 	case 3:
@@ -279,12 +281,17 @@ xchk_dinode(
 		if (dip->di_projid_hi != 0 &&
 		    !xfs_has_projid32(mp))
 			xchk_ino_set_corrupt(sc, ino);
+
+		prid = be16_to_cpu(dip->di_projid_lo);
 		break;
 	default:
 		xchk_ino_set_corrupt(sc, ino);
 		return;
 	}
 
+	if (xfs_has_projid32(mp))
+		prid |= (prid_t)be16_to_cpu(dip->di_projid_hi) << 16;
+
 	/*
 	 * di_uid/di_gid -- -1 isn't invalid, but there's no way that
 	 * userspace could have created that.
@@ -293,6 +300,13 @@ xchk_dinode(
 	    dip->di_gid == cpu_to_be32(-1U))
 		xchk_ino_set_warning(sc, ino);
 
+	/*
+	 * project id of -1 isn't supposed to be valid, but the kernel didn't
+	 * always validate that.
+	 */
+	if (prid == -1U)
+		xchk_ino_set_warning(sc, ino);
+
 	/* di_format */
 	switch (dip->di_format) {
 	case XFS_DINODE_FMT_DEV: