[Ocfs2-tools-devel] [PATCH 1/3] tunefs.ocfs2: Don't use the I/O cache in unlocked or online operations.

[Sunil Mushran]

Signed-off-by: Sunil Mushran <sunil.mushran at oracle.com>


Joel Becker wrote:
> It's not safe to cache disk blocks when the filesystem may be live
> elsewhere.  So if we're running any of the "special" operations, ones
> that get the special error codes (SKIPCLUSTER, PERFORM_ONLINE, etc),
> we'll run without the cache.
>
> Because ocfs2ne runs the special operations first, then closes the
> filesystem and repoens it before trying regular operations, we know that
> regular operations will get the cache if they can safely lock the
> filesystem.
>
> Signed-off-by: Joel Becker <joel.becker at oracle.com>
> ---
>  tunefs.ocfs2/libocfs2ne.c |   14 +++++++++++---
>  1 files changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/tunefs.ocfs2/libocfs2ne.c b/tunefs.ocfs2/libocfs2ne.c
> index c5362db..fb800cb 100644
> --- a/tunefs.ocfs2/libocfs2ne.c
> +++ b/tunefs.ocfs2/libocfs2ne.c
> @@ -1370,10 +1370,18 @@ errcode_t tunefs_open(const char *device, int flags,
>  	/*
>  	 * We will use block cache in io.  Now, whether the cluster is
>  	 * locked or the volume is mount local, in both situation we can
> -	 * safely use cache.  If io_init_cache failed, we will go on the
> -	 * tunefs work without the io_cache, so there is no check here.
> +	 * safely use cache.  If we're not locked
> +	 * (tunefs_special_errorp(err) != 0), we can't safely use it.
> +	 * If this tunefs run has both special and regular operations,
> +	 * ocfs2ne will retry with the regular arguments and will get
> +	 * the cache for the regular operations.
> +	 *
> +	 * If io_init_cache failed, we will go do the work without the
> +	 * io_cache, so there is no check for failure here.
>  	 */
> -	io_init_cache(fs->fs_io, ocfs2_extent_recs_per_eb(fs->fs_blocksize));
> +	if (!err)
> +		io_init_cache(fs->fs_io,
> +			      ocfs2_extent_recs_per_eb(fs->fs_blocksize));
>  
>  	/*
>  	 * SKIPCLUSTER operations don't check the journals - they couldn't
>