On Tue, Oct 07, 2014 at 10:41:14AM -0000, stef...@apache.org wrote:
> Author: stefan2
> Date: Tue Oct 7 10:41:14 2014
> New Revision: 1629854
>
> URL: http://svn.apache.org/r1629854
> Log:
> In FSFS, always use the same function to read the 'current' file.
>
> Apart from the consistency aspect, this no longer lets atoi() mask
> 'current' file corruptions. Recovery must be adopted to this.
Hi Stefan,
Two questions below:
> --- subversion/trunk/subversion/libsvn_fs_fs/fs.c (original)
> +++ subversion/trunk/subversion/libsvn_fs_fs/fs.c Tue Oct 7 10:41:14 2014
> @@ -348,20 +349,47 @@ fs_open_for_recovery(svn_fs_t *fs,
> apr_pool_t *pool,
> apr_pool_t *common_pool)
> {
> + svn_error_t * err;
> + svn_revnum_t youngest_rev;
> + apr_pool_t * subpool = svn_pool_create(pool);
> +
> /* Recovery for FSFS is currently limited to recreating the 'current'
> file from the latest revision. */
>
> /* The only thing we have to watch out for is that the 'current' file
> - might not exist. So we'll try to create it here unconditionally,
> - and just ignore any errors that might indicate that it's already
> - present. (We'll need it to exist later anyway as a source for the
> - new file's permissions). */
> + might not exist or contain garbage. So we'll try to read it here
> + and provide or replace the existing file if we couldn't read it.
> + (We'll also need it to exist later anyway as a source for the new
> + file's permissions). */
>
> - /* Use a partly-filled fs pointer first to create 'current'. This will
> fail
> - if 'current' already exists, but we don't care about that. */
> + /* Use a partly-filled fs pointer first to create 'current'. */
> fs->path = apr_pstrdup(fs->pool, path);
> - svn_error_clear(svn_io_file_create(svn_fs_fs__path_current(fs, pool),
> - "0 1 1\n", pool));
> +
> + SVN_ERR(initialize_fs_struct(fs));
The 'fs' struct is provided by the caller and is now initialised
and uninitialised within this function. Can't this function
use a local 'fs' variable? If not, why does it need to be uninitialised
again? This is a bit confusing -- though perhaps it's an idiom used in
the FS code that I'm not aware of?
> +
> + /* Figure out the repo format and check that we can even handle it. */
> + SVN_ERR(svn_fs_fs__read_format_file(fs, subpool));
> +
> + /* Now, read 'current' and try to patch it if necessary. */
> + err = svn_fs_fs__youngest_rev(&youngest_rev, fs, subpool);
> + if (err)
Can't we check for a specific error code here, and return the
error otherwise? This would make the intention of the error handling
code explicit and avoid masking of arbitrary error conditions.
> + {
> + const char *file_path;
> +
> + /* 'current' file is missing or contains garbage.
> + * Start with HEAD = 0 in that case. */
> + svn_error_clear(err);
> + file_path = svn_fs_fs__path_current(fs, subpool);
> +
> + /* Best effort to ensure the file exists and is valid.
> + * This may fail for r/o filesystems etc. */
> + SVN_ERR(svn_io_remove_file2(file_path, TRUE, subpool));
> + SVN_ERR(svn_io_file_create_empty(file_path, subpool));
> + SVN_ERR(svn_fs_fs__write_current(fs, 0, 1, 1, subpool));
> + }
> +
> + uninitialize_fs_struct(fs);
> + svn_pool_destroy(subpool);
>
> /* Now open the filesystem properly by calling the vtable method directly.
> */
> return fs_open(fs, path, common_pool_lock, pool, common_pool);
>
