Re: svn commit: r1358322 - /subversion/trunk/subversion/libsvn_fs_fs/tree.c

[Blair Zajac <bl...@orcaware.com>]

On 7/6/12 11:04 AM, stefan2@apache.org wrote:
> Author: stefan2
> Date: Fri Jul  6 18:04:09 2012
> New Revision: 1358322
>
> URL: http://svn.apache.org/viewvc?rev=1358322&view=rev
> Log:
> Relax overly strict consistency check that is not covered by the FSFS
> format specification.
>
> * subversion/libsvn_fs_fs/tree.c
>    (svn_fs_fs__verify_root): fix test and add commentary
>
> Modified:
>      subversion/trunk/subversion/libsvn_fs_fs/tree.c
>
> Modified: subversion/trunk/subversion/libsvn_fs_fs/tree.c
> URL: http://svn.apache.org/viewvc/subversion/trunk/subversion/libsvn_fs_fs/tree.c?rev=1358322&r1=1358321&r2=1358322&view=diff
> ==============================================================================
> --- subversion/trunk/subversion/libsvn_fs_fs/tree.c (original)
> +++ subversion/trunk/subversion/libsvn_fs_fs/tree.c Fri Jul  6 18:04:09 2012
> @@ -3881,6 +3881,7 @@ svn_fs_fs__verify_root(svn_fs_root_t *ro
>       const svn_fs_id_t *pred_id;
>       dag_node_t *pred;
>       svn_revnum_t pred_rev;
> +    svn_revnum_t delta;
>
>       /* Only r0 should have no predecessor. */
>       SVN_ERR(svn_fs_fs__dag_get_predecessor_id(&pred_id, frd->root_dir));
> @@ -3898,8 +3899,23 @@ svn_fs_fs__verify_root(svn_fs_root_t *ro
>         {
>           SVN_ERR(svn_fs_fs__dag_get_node(&pred, root->fs, pred_id, pool));
>           SVN_ERR(svn_fs_fs__dag_get_revision(&pred_rev, pred, pool));
> -        if (pred_rev+1 != root->rev)
> -          /* Issue #4129. */
> +
> +        /* Issue #4129: bogus predecessors. */
> +        /* Check 1: predecessor must be an earlier revision.
> +         */
> +        if (pred_rev >= root->rev)
> +          return svn_error_createf(SVN_ERR_FS_CORRUPT, NULL,
> +                                   "r%ld's root node's predecessor is r%ld",
> +                                   root->rev, pred_rev);

Suggest describing in the error message the condition that failed.

> +
> +        /* Check 2: distances must be a power of 2.
> +         * Note that this condition is not defined by the FSFS format but
> +         * merely a byproduct of the current implementation. Therefore,
> +         * it may help to spot corruptions for the time being but might
> +         * need to be removed / relaxed in later versions.
> +         */
> +        delta = root->rev - pred_rev;
> +        if (delta & (delta - 1))
>             return svn_error_createf(SVN_ERR_FS_CORRUPT, NULL,
>                                      "r%ld's root node's predecessor is r%ld",
>                                      root->rev, pred_rev);

Same here.  This will make it easier for people who are not familiar with fsfs's 
internals to see which condition failed.

Blair