xfs: limit superblock corruption errors to actual corruption

Today, if

xfs_sb_read_verify
  xfs_sb_verify
    xfs_mount_validate_sb

detects superblock corruption, it'll be extremely noisy, dumping
2 stacks, 2 hexdumps, etc.

This is because we call XFS_CORRUPTION_ERROR in xfs_mount_validate_sb
as well as in xfs_sb_read_verify.

Also, *any* errors in xfs_mount_validate_sb which are not corruption
per se; things like too-big-blocksize, bad version, bad magic, v1 dirs,
rw-incompat etc - things which do not return EFSCORRUPTED - will
still do the whole XFS_CORRUPTION_ERROR spew when xfs_sb_read_verify
sees any error at all.  And it suggests to the user that they
should run xfs_repair, even if the root cause of the mount failure
is a simple incompatibility.

I'll submit that the probably-not-corrupted errors don't warrant
this much noise, so this patch removes the warning for anything
other than EFSCORRUPTED returns, and replaces the lower-level
XFS_CORRUPTION_ERROR with an xfs_notice().
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/xfs_sb.c

@@ -295,8 +295,7 @@ xfs_mount_validate_sb(
 	    sbp->sb_dblocks == 0					||
 	    sbp->sb_dblocks > XFS_MAX_DBLOCKS(sbp)			||
 	    sbp->sb_dblocks < XFS_MIN_DBLOCKS(sbp))) {
-		XFS_CORRUPTION_ERROR("SB sanity check failed",
-				XFS_ERRLEVEL_LOW, mp, sbp);
+		xfs_notice(mp, "SB sanity check failed");
 		return XFS_ERROR(EFSCORRUPTED);
 	}
 
@@ -625,7 +624,7 @@ xfs_sb_read_verify(
 
 out_error:
 	if (error) {
-		if (error != EWRONGFS)
+		if (error == EFSCORRUPTED)
 			XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW,
 					     mp, bp->b_addr);
 		xfs_buf_ioerror(bp, error);