Re: [Qemu-devel] [PATCH V3 1/7] block/qemu-img: Refine and export infinite loop checking in collect_image_info_list()

[Fam Zheng <famz@redhat.com>]

On Mon, 07/15 05:42, Xu Wang wrote:
> If there is a loop exists in the backing file chain, many problems
> could be caused by it, such as no response and segment fault during
> system boot. Hence stopping backing file loop appear is very necessary.
> This patch refine and export loop checking function from collect_image_
> info_list() to block.c and build a independent function named bdrv_
> backing_file_loop_check().
> 
> Signed-off-by: Xu Wang <cngesaint@gmail.com>
> ---
>  block.c               | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/block/block.h |  4 +++
>  qemu-img.c            | 29 +++++----------
>  3 files changed, 110 insertions(+), 20 deletions(-)
> 
> diff --git a/block.c b/block.c
> index 183fec8..c1d060d 100644
> --- a/block.c
> +++ b/block.c
> @@ -4433,6 +4433,103 @@ bdrv_acct_done(BlockDriverState *bs, BlockAcctCookie *cookie)
>      bs->total_time_ns[cookie->type] += get_clock() - cookie->start_time_ns;
>  }
>  
> +static gboolean str_equal_func(gconstpointer a, gconstpointer b)
> +{
> +    return strcmp(a, b) == 0;
> +}
> +
> +/**
> + * Check backing file chain if there is a loop in it and build list of
> + * ImageInfo if needed.

Need fix for this? Image info built in collect_image_info_list, not
here, right?

Fam

> + *
> + * @filename: topmost image filename, absolute or relative path is OK.
> + * @fmt: topmost image format (may be NULL to autodetect)
> + * @backing_file: if this value is set, @filename inode (-1 if it doesn't
> + *                exist) will insert into hash table directly. Loop check
> + *                starts from it. Absolute or relative path is OK for it.
> + * @backing_format: format of backing file
> + *
> + * Returns: true for backing file loop or error happened, false for no loop.
> + */
> +bool bdrv_backing_file_loop_check(const char *filename, const char *fmt,
> +                                  const char *backing_file,
> +                                  const char *backing_format) {