share xfs_ondisk.h with userspace

share xfs_ondisk.h with userspace

[Christoph Hellwig]

Hi all,

this series switches xfs_ondisk.h to use static_assert instead of the
kernel-specific BUILD_BUG_ON_MSG and then moves it to libxfs so that
userspace can share the same struct sanity checks.

Diffstat:
 xfs_ondisk.h |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

[PATCH 1/2] xfs: use static_assert to check struct sizes and offsets

[Christoph Hellwig]

Use the compiler-provided static_assert built-in from C11 instead of
the kernel-specific BUILD_BUG_ON_MSG for the structure size and offset
checks in xfs_ondisk.  This not only gives slightly nicer error messages
in case things go south, but can also be trivially used as-is in
userspace.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/xfs_ondisk.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/xfs_ondisk.h b/fs/xfs/xfs_ondisk.h
index 21a7e350b4c58e..d9c988c5ad692e 100644
--- a/fs/xfs/xfs_ondisk.h
+++ b/fs/xfs/xfs_ondisk.h
@@ -7,16 +7,16 @@
 #define __XFS_ONDISK_H
 
 #define XFS_CHECK_STRUCT_SIZE(structname, size) \
-	BUILD_BUG_ON_MSG(sizeof(structname) != (size), "XFS: sizeof(" \
-		#structname ") is wrong, expected " #size)
+	static_assert(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), \
+	static_assert(offsetof(structname, member) == (off), \
 		"XFS: offsetof(" #structname ", " #member ") is wrong, " \
 		"expected " #off)
 
 #define XFS_CHECK_VALUE(value, expected) \
-	BUILD_BUG_ON_MSG((value) != (expected), \
+	static_assert((value) == (expected), \
 		"XFS: value of " #value " is wrong, expected " #expected)
 
 static inline void __init
-- 
2.39.2

[PATCH 2/2] xfs: move xfs_ondisk.h to libxfs/

[Christoph Hellwig]

Move xfs_ondisk.h to libxfs so that we can do the struct sanity checks
in userspace libxfs as well.  This should allow us to retire the
somewhat fragile xfs/122 test on xfstests.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/{ => libxfs}/xfs_ondisk.h | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 rename fs/xfs/{ => libxfs}/xfs_ondisk.h (100%)

diff --git a/fs/xfs/xfs_ondisk.h b/fs/xfs/libxfs/xfs_ondisk.h
similarity index 100%
rename from fs/xfs/xfs_ondisk.h
rename to fs/xfs/libxfs/xfs_ondisk.h
-- 
2.39.2

Re: [PATCH 2/2] xfs: move xfs_ondisk.h to libxfs/

[Darrick J. Wong]

On Mon, Dec 04, 2023 at 09:07:19PM +0100, Christoph Hellwig wrote:
> Move xfs_ondisk.h to libxfs so that we can do the struct sanity checks
> in userspace libxfs as well.  This should allow us to retire the
> somewhat fragile xfs/122 test on xfstests.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Yay build time checks!
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>  fs/xfs/{ => libxfs}/xfs_ondisk.h | 0
>  1 file changed, 0 insertions(+), 0 deletions(-)
>  rename fs/xfs/{ => libxfs}/xfs_ondisk.h (100%)
> 
> diff --git a/fs/xfs/xfs_ondisk.h b/fs/xfs/libxfs/xfs_ondisk.h
> similarity index 100%
> rename from fs/xfs/xfs_ondisk.h
> rename to fs/xfs/libxfs/xfs_ondisk.h
> -- 
> 2.39.2
> 
> 

Re: share xfs_ondisk.h with userspace

[Carlos Maiolino]

On Mon, Dec 04, 2023 at 09:07:17PM +0100, Christoph Hellwig wrote:
> Hi all,
> 
> this series switches xfs_ondisk.h to use static_assert instead of the
> kernel-specific BUILD_BUG_ON_MSG and then moves it to libxfs so that
> userspace can share the same struct sanity checks.

Thanks Christoph!

Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>


> 
> Diffstat:
>  xfs_ondisk.h |    8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>