[PATCH] xfs: check sizes of XFS on-disk structures at compile time

["Darrick J. Wong" <darrick.wong@xxxxxxxxxx>]

Check the sizes of XFS on-disk structures when compiling the kernel.
Use this to catch inadvertent changes in structure size due to padding
and alignment issues, etc.

Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
 fs/xfs/libxfs/xfs_format.h |    4 ++++
 fs/xfs/xfs_super.c         |   45 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index e2536bb..a589b47 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -1509,4 +1509,8 @@ struct xfs_acl {
 #define SGI_ACL_FILE_SIZE      (sizeof(SGI_ACL_FILE)-1)
 #define SGI_ACL_DEFAULT_SIZE   (sizeof(SGI_ACL_DEFAULT)-1)
 
+#define XFS_CHECK_STRUCT_SIZE(structname, size) \
+       BUILD_BUG_ON_MSG(sizeof(structname) != (size), "XFS: sizeof(struct " \
+               #structname ") is wrong, expected " #size)
+
 #endif /* __XFS_FORMAT_H__ */
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);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_disk_dquot,            104);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_dqblk,                 136);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_dsymlink_hdr,          56);
+       XFS_CHECK_STRUCT_SIZE(xfs_alloc_rec_t,                  8);
+       XFS_CHECK_STRUCT_SIZE(xfs_alloc_key_t,                  8);
+       XFS_CHECK_STRUCT_SIZE(xfs_alloc_ptr_t,                  4);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_inobt_rec,             16);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_inobt_key,             4);
+       XFS_CHECK_STRUCT_SIZE(xfs_inobt_ptr_t,                  4);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_bmdr_block,            4);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_bmbt_rec,              16);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_bmbt_key,              8);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_btree_block,           72);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_acl_entry,             12);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_acl,                   4);
+
+       /* log structures */
+       XFS_CHECK_STRUCT_SIZE(struct xfs_trans_header,          16);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_inode_log_format_32,   52);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_inode_log_format_64,   56);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_ictimestamp,           8);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_icdinode,              176);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_extent_32,             12);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_extent_64,             16);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_efi_log_format_32,     28);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_efi_log_format_64,     32);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_efd_log_format_32,     28);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_efd_log_format_64,     32);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_dq_logformat,          24);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_qoff_logformat,        20);
+       XFS_CHECK_STRUCT_SIZE(struct xfs_icreate_log,           28);
+}
+
 STATIC int __init
 init_xfs_fs(void)
 {
        int                     error;
 
+       xfs_check_ondisk_structs();
+
        printk(KERN_INFO XFS_VERSION_STRING " with "
                         XFS_BUILD_OPTIONS " enabled\n");