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Date: Mon, 28 Mar 2016 15:47:10 -0700
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: Dave Chinner <david@...morbit.com>
Cc: Geert Uytterhoeven <geert@...ux-m68k.org>,
Linux-sh list <linux-sh@...r.kernel.org>,
Rich Felker <dalias@...c.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Cris <linux-cris-kernel@...s.com>, xfs@....sgi.com
Subject: Re: Build regressions/improvements in v4.6-rc1
On Tue, Mar 29, 2016 at 08:59:23AM +1100, Dave Chinner wrote:
> On Sun, Mar 27, 2016 at 02:43:24PM +0200, Geert Uytterhoeven wrote:
> > On Sun, Mar 27, 2016 at 2:39 PM, Geert Uytterhoeven
> > <geert@...ux-m68k.org> wrote:
> > > Below is the list of build error/warning regressions/improvements in
> > > v4.6-rc1[1] compared to v4.5[2].
> > >
> > > Summarized:
> > > - build errors: +9/-6
> >
> > > [1] http://kisskb.ellerman.id.au/kisskb/head/10114/ (all 262 configs)
> > > [2] http://kisskb.ellerman.id.au/kisskb/head/10047/ (all 262 configs)
> >
> > > 9 error regressions:
> > > + /home/kisskb/slave/src/fs/xfs/xfs_ondisk.h: error: call to
> > > '__compiletime_assert_79' declared with attribute error: XFS:
> > > sizeof(xfs_attr_shortform_t) is wrong, expected 8: => 79:2
> >
> > cris-allyesconfig, cris-allmodconfig
>
> Yup, cris is the only platform that throws this error on this
> structure. It's an on-disk structure and relying on the gcc
> optimiser to do the same thing from release to release has become
> such a crap-shoot these days. Hence as a stop-gap measure we added
> build time checking of what they compiler is doing with those
> structures, and to refuse to build XFS if the compiler/platform is
> doing something obviously different.
>
> Modernising the on-disk structure definitions is on the list of
> things to do, but it's nowhere near the top of my list at the
> moment...
I have a test patch that (for now) changes the ondisk format checks for the
variable-length structures to look at the offsets of the non-variable-length
fields. Can you give it a try?
(No idea if it fixes fixes cris, but it passes the six arches that I can
actually test on (x86/power/arm)). The downside is that it does nothing about
troubling implication that there could be computers writing out a disk format
that's incompatible with x86 XFSes...)
--D
-----------
From: Darrick J. Wong <darrick.wong@...cle.com>
Subject: [PATCH] xfs: check offsets of variable length structures
Some of the directory/attr structures contain variable-length objects,
so the enclosing structure doesn't have a meaningful fixed size at
compile time. We can check the offsets of the members before the
variable-length member, so do those.
Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
---
fs/xfs/xfs_ondisk.h | 25 +++++++++++++++++++++++--
1 file changed, 23 insertions(+), 2 deletions(-)
diff --git a/fs/xfs/xfs_ondisk.h b/fs/xfs/xfs_ondisk.h
index 960648b..3742216 100644
--- a/fs/xfs/xfs_ondisk.h
+++ b/fs/xfs/xfs_ondisk.h
@@ -22,6 +22,11 @@
BUILD_BUG_ON_MSG(sizeof(structname) != (size), "XFS: sizeof(" \
#structname ") is wrong, expected " #size)
+#define XFS_CHECK_OFFSET(structname, member, off) \
+ BUILD_BUG_ON_MSG(offsetof(structname, member) != (off), \
+ "XFS: offsetof(" #structname ", " #member ") is wrong, " \
+ "expected " #off)
+
static inline void __init
xfs_check_ondisk_structs(void)
{
@@ -81,15 +86,28 @@ xfs_check_ondisk_structs(void)
XFS_CHECK_STRUCT_SIZE(xfs_attr_leaf_name_remote_t, 12);
*/
+ XFS_CHECK_OFFSET(xfs_attr_leaf_name_local_t, valuelen, 0);
+ XFS_CHECK_OFFSET(xfs_attr_leaf_name_local_t, namelen, 2);
+ XFS_CHECK_OFFSET(xfs_attr_leaf_name_local_t, nameval, 3);
+ XFS_CHECK_OFFSET(xfs_attr_leaf_name_remote_t, valueblk, 0);
+ XFS_CHECK_OFFSET(xfs_attr_leaf_name_remote_t, valuelen, 4);
+ XFS_CHECK_OFFSET(xfs_attr_leaf_name_remote_t, namelen, 8);
+ XFS_CHECK_OFFSET(xfs_attr_leaf_name_remote_t, name, 9);
XFS_CHECK_STRUCT_SIZE(xfs_attr_leafblock_t, 40);
- XFS_CHECK_STRUCT_SIZE(xfs_attr_shortform_t, 8);
+ XFS_CHECK_OFFSET(xfs_attr_shortform_t, hdr.totsize, 0);
+ XFS_CHECK_OFFSET(xfs_attr_shortform_t, hdr.count, 2);
+ XFS_CHECK_OFFSET(xfs_attr_shortform_t, list[0].namelen, 4);
+ XFS_CHECK_OFFSET(xfs_attr_shortform_t, list[0].valuelen, 5);
+ XFS_CHECK_OFFSET(xfs_attr_shortform_t, list[0].flags, 6);
+ XFS_CHECK_OFFSET(xfs_attr_shortform_t, list[0].nameval, 7);
XFS_CHECK_STRUCT_SIZE(xfs_da_blkinfo_t, 12);
XFS_CHECK_STRUCT_SIZE(xfs_da_intnode_t, 16);
XFS_CHECK_STRUCT_SIZE(xfs_da_node_entry_t, 8);
XFS_CHECK_STRUCT_SIZE(xfs_da_node_hdr_t, 16);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_data_free_t, 4);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_data_hdr_t, 16);
- XFS_CHECK_STRUCT_SIZE(xfs_dir2_data_unused_t, 6);
+ XFS_CHECK_OFFSET(xfs_dir2_data_unused_t, freetag, 0);
+ XFS_CHECK_OFFSET(xfs_dir2_data_unused_t, length, 2);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_free_hdr_t, 16);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_free_t, 16);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_ino4_t, 4);
@@ -100,6 +118,9 @@ xfs_check_ondisk_structs(void)
XFS_CHECK_STRUCT_SIZE(xfs_dir2_leaf_t, 16);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_leaf_tail_t, 4);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_sf_entry_t, 3);
+ XFS_CHECK_OFFSET(xfs_dir2_sf_entry_t, namelen, 0);
+ XFS_CHECK_OFFSET(xfs_dir2_sf_entry_t, offset, 1);
+ XFS_CHECK_OFFSET(xfs_dir2_sf_entry_t, name, 3);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_sf_hdr_t, 10);
XFS_CHECK_STRUCT_SIZE(xfs_dir2_sf_off_t, 2);
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