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From: Eric Sandeen <sandeen@sandeen.net>
To: xfs@oss.sgi.com
Subject: Re: [PATCH] xfs: check sizes of XFS on-disk structures at compile time
Date: Wed, 13 Jan 2016 12:25:26 -0600	[thread overview]
Message-ID: <56969696.2040206@sandeen.net> (raw)
In-Reply-To: <20160111232657.GA7831@birch.djwong.org>

On 1/11/16 5:26 PM, Darrick J. Wong wrote:

> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 36bd882..31b69d1 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -1812,11 +1812,56 @@ xfs_destroy_workqueues(void)
>  	destroy_workqueue(xfs_alloc_wq);
>  }
>  
> +static void __init
> +xfs_check_ondisk_structs(void)
> +{
> +	/* on-disk structures */
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_dsb,			264);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_agf,			224);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_agi,			336);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_agfl,			36);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_timestamp,		8);
> +	XFS_CHECK_STRUCT_SIZE(struct xfs_dinode,		176);

I'm not sure why, but all this hard-coded stuff in the codebase bugs me.

What if we did it as part of the build, but outside the code, something
like (pardon my bad Make-fu):

diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index f646391..da9ec6d 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -122,3 +122,8 @@ xfs-$(CONFIG_XFS_POSIX_ACL) += xfs_acl.o
 xfs-$(CONFIG_SYSCTL)           += xfs_sysctl.o
 xfs-$(CONFIG_COMPAT)           += xfs_ioctl32.o
 xfs-$(CONFIG_NFSD_PNFS)                += xfs_pnfs.o
+
+check_structures: $(obj)/xfs.o
+       $(src)/scripts/check_structures.sh $(obj)/xfs.o
+
+$(obj)/built-in.o: check_structures

where the script executes pahole or whatever we want, to check the
structure sizes and possibly even alignment explicitly?  Presumably
we could make running the check a Kconfig option as well...

similar tricks could surely be done for userspace as well.

-Eric

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  parent reply	other threads:[~2016-01-13 18:25 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-11 23:26 [PATCH] xfs: check sizes of XFS on-disk structures at compile time Darrick J. Wong
2016-01-12 14:01 ` Brian Foster
2016-01-13 18:25 ` Eric Sandeen [this message]
2016-01-15 21:05   ` Darrick J. Wong
2016-01-15 20:58 ` Darrick J. Wong
2016-01-15 22:52   ` Dave Chinner
2016-01-20  5:12     ` Darrick J. Wong
2016-01-20 15:40     ` Josef 'Jeff' Sipek
2016-01-22 22:01       ` Darrick J. Wong
2016-02-01  5:06         ` Dave Chinner

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