Re: [PATCH v5 5/5] parallels: Image repairing in parallels_open()

[Alexander Ivanov]

On 6/9/23 15:41, Hanna Czenczek wrote:
> On 09.06.23 15:21, Alexander Ivanov wrote:
> > On 6/2/23 16:59, Hanna Czenczek wrote:
> > > On 29.05.23 17:15, Alexander Ivanov wrote:
> > > > Repair an image at opening if the image is unclean or out-of-image
> > > > corruption was detected.
> > > >
> > > > Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
> > > > ---
> > > >   block/parallels.c | 65 
> > > > +++++++++++++++++++++++++----------------------
> > > >   1 file changed, 35 insertions(+), 30 deletions(-)
> > > >
> > > > diff --git a/block/parallels.c b/block/parallels.c
> > > > index d64e8007d5..7bbd5cb112 100644
> > > > --- a/block/parallels.c
> > > > +++ b/block/parallels.c
> > >
> > > [...]
> > >
> > > > @@ -1130,6 +1101,40 @@ static int parallels_open(BlockDriverState 
> > > > *bs, QDict *options, int flags,
> > > >           goto fail;
> > > >       }
> > > >       qemu_co_mutex_init(&s->lock);
> > > > +
> > > > +    if (le32_to_cpu(ph.inuse) == HEADER_INUSE_MAGIC) {
> > > > +        s->header_unclean = true;
> > > > +    }
> > > > +
> > > > +    for (i = 0; i < s->bat_size; i++) {
> > > > +        sector = bat2sect(s, i);
> > > > +        if (sector + s->tracks > s->data_end) {
> > > > +            s->data_end = sector + s->tracks;
> > > > +        }
> > > > +    }
> > > > +
> > > > +    /*
> > > > +     * We don't repair the image here if it's opened for checks. 
> > > > Also we don't
> > > > +     * want to change inactive images and can't change readonly 
> > > > images.
> > > > +     */
> > > > +    if ((flags & (BDRV_O_CHECK | BDRV_O_INACTIVE)) || !(flags & 
> > > > BDRV_O_RDWR)) {
> > > > +        return 0;
> > > > +    }
> > > > +
> > > > +    /*
> > > > +     * Repair the image if it's dirty or
> > > > +     * out-of-image corruption was detected.
> > > > +     */
> > > > +    if (s->data_end > file_nb_sectors || s->header_unclean) {
> > > > +        BdrvCheckResult res;
> > > > +        ret = bdrv_check(bs, &res, BDRV_FIX_ERRORS | BDRV_FIX_LEAKS);
> > > > +        if (ret < 0) {
> > >
> > > Should we also verify that res->corruptions == 
> > > res->corruptions_fixed && res->check_errors == 0?
> > If ret == 0 there must be res->check_errors == 0 and res->corruptions 
> > == res->corruptions_fixed.
>
> OK.
>
> > > > + error_free(s->migration_blocker);
> > >
> > > I’d move this clean-up to a new error path below, then we could even 
> > > reuse that where migrate_add_blocker() fails.
> > Is this guaranteed that s->migration_blocker is NULL at the function 
> > parallels_open() beginning? If so it could be easy to move the clean-up,
> > otherwise it could lead to code complication.
>
> Three answers here:
>
> First, I just realized that we probably need to undo the 
> migrate_add_blocker() call, too, i.e. call migrate_del_blocker() here.
>
> Second, I’m pretty sure that s->migration_blocker must be NULL before 
> the error_setg(&s->migration_blocker) call, because error_setg() 
> asserts that the *errp passed to it is NULL.
>
> Third, I meant to add a new path e.g.:
>
> ```
> fail_blocker:
>     error_free(s->migration_blocker);
> fail_format:
> [...]
> ```
>
> And then use `goto fail_blocker;` here and in the 
> migrate_add_blocker() error path, so it shouldn’t really matter 
> whether s->migration_blocker is NULL before the error_setg() call.  
> But then again, I think the probably necessary migrate_del_blocker() 
> call complicates things further.
>
> Hanna
Do we need to run the rest part of the parallels_close() code?

    if ((bs->open_flags & BDRV_O_RDWR) && !(bs->open_flags & 
BDRV_O_INACTIVE)) {
        s->header->inuse = 0;
        parallels_update_header(bs);

        /* errors are ignored, so we might as well pass exact=true */
        bdrv_truncate(bs->file, s->data_end << BDRV_SECTOR_BITS, true,
                      PREALLOC_MODE_OFF, 0, NULL);
    }

    g_free(s->bat_dirty_bmap);

If so, maybe it would be better to call parallels_close()?

> > > Anyway, not wrong as-is, just suggestion, so:
> > >
> > > Reviewed-by: Hanna Czenczek <hreitz@redhat.com>
> > >
> > > > +            error_setg_errno(errp, -ret, "Could not repair 
> > > > corrupted image");
> > > > +            goto fail;
> > > > +        }
> > > > +    }
> > > > +
> > > >       return 0;
> > > >     fail_format:

--
Best regards,
Alexander Ivanov