1 files changed, 36 insertions, 13 deletions

diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 3d33e17f2e5c..000cc7f4a3ce 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -33,8 +33,6 @@ struct kmem_cache	*xfs_extfree_item_cache;
 
 struct workqueue_struct *xfs_alloc_wq;
 
-#define XFS_ABSDIFF(a,b)	(((a) <= (b)) ? ((b) - (a)) : ((a) - (b)))
-
 #define	XFSA_FIXUP_BNO_OK	1
 #define	XFSA_FIXUP_CNT_OK	2
 
@@ -410,8 +408,8 @@ xfs_alloc_compute_diff(
 		if (newbno1 != NULLAGBLOCK && newbno2 != NULLAGBLOCK) {
 			if (newlen1 < newlen2 ||
 			    (newlen1 == newlen2 &&
-			     XFS_ABSDIFF(newbno1, wantbno) >
-			     XFS_ABSDIFF(newbno2, wantbno)))
+			     abs_diff(newbno1, wantbno) >
+			     abs_diff(newbno2, wantbno)))
 				newbno1 = newbno2;
 		} else if (newbno2 != NULLAGBLOCK)
 			newbno1 = newbno2;
@@ -427,7 +425,7 @@ xfs_alloc_compute_diff(
 	} else
 		newbno1 = freeend - wantlen;
 	*newbnop = newbno1;
-	return newbno1 == NULLAGBLOCK ? 0 : XFS_ABSDIFF(newbno1, wantbno);
+	return newbno1 == NULLAGBLOCK ? 0 : abs_diff(newbno1, wantbno);
 }
 
 /*
@@ -3446,16 +3444,41 @@ xfs_alloc_read_agf(
 
 		set_bit(XFS_AGSTATE_AGF_INIT, &pag->pag_opstate);
 	}
+
 #ifdef DEBUG
-	else if (!xfs_is_shutdown(mp)) {
-		ASSERT(pag->pagf_freeblks == be32_to_cpu(agf->agf_freeblks));
-		ASSERT(pag->pagf_btreeblks == be32_to_cpu(agf->agf_btreeblks));
-		ASSERT(pag->pagf_flcount == be32_to_cpu(agf->agf_flcount));
-		ASSERT(pag->pagf_longest == be32_to_cpu(agf->agf_longest));
-		ASSERT(pag->pagf_bno_level == be32_to_cpu(agf->agf_bno_level));
-		ASSERT(pag->pagf_cnt_level == be32_to_cpu(agf->agf_cnt_level));
+	/*
+	 * It's possible for the AGF to be out of sync if the block device is
+	 * silently dropping writes. This can happen in fstests with dmflakey
+	 * enabled, which allows the buffer to be cleaned and reclaimed by
+	 * memory pressure and then re-read from disk here. We will get a
+	 * stale version of the AGF from disk, and nothing good can happen from
+	 * here. Hence if we detect this situation, immediately shut down the
+	 * filesystem.
+	 *
+	 * This can also happen if we are already in the middle of a forced
+	 * shutdown, so don't bother checking if we are already shut down.
+	 */
+	if (!xfs_is_shutdown(pag_mount(pag))) {
+		bool	ok = true;
+
+		ok &= pag->pagf_freeblks == be32_to_cpu(agf->agf_freeblks);
+		ok &= pag->pagf_freeblks == be32_to_cpu(agf->agf_freeblks);
+		ok &= pag->pagf_btreeblks == be32_to_cpu(agf->agf_btreeblks);
+		ok &= pag->pagf_flcount == be32_to_cpu(agf->agf_flcount);
+		ok &= pag->pagf_longest == be32_to_cpu(agf->agf_longest);
+		ok &= pag->pagf_bno_level == be32_to_cpu(agf->agf_bno_level);
+		ok &= pag->pagf_cnt_level == be32_to_cpu(agf->agf_cnt_level);
+
+		if (XFS_IS_CORRUPT(pag_mount(pag), !ok)) {
+			xfs_ag_mark_sick(pag, XFS_SICK_AG_AGF);
+			xfs_trans_brelse(tp, agfbp);
+			xfs_force_shutdown(pag_mount(pag),
+					SHUTDOWN_CORRUPT_ONDISK);
+			return -EFSCORRUPTED;
+		}
 	}
-#endif
+#endif /* DEBUG */
+
 	if (agfbpp)
 		*agfbpp = agfbp;
 	else