[Libguestfs] [PATCH v3 2/2] New API: btfs_scrub_status

[Chen, Hanxiao]

> -----Original Message-----
> From: Richard W.M. Jones [mailto:rjones at redhat.com]
> Sent: Wednesday, February 11, 2015 10:04 PM
> To: Chen, Hanxiao/陈 晗霄
> Cc: libguestfs at redhat.com
> Subject: Re: [Libguestfs] [PATCH v3 2/2] New API: btfs_scrub_status
> 
> On Wed, Feb 11, 2015 at 06:41:20PM +0800, Chen Hanxiao wrote:
> > +  /* Output of `btrfs scrub -R status' is like:
> > +   *
> > +   *   scrub status for 346121d1-1847-40f8-9b7b-2bf3d539c68f
> > +   *           scrub started at Mon Feb  2 17:39:38 2015, running for 93 seconds
> > +   *           data_extents_scrubbed: 136670
> > +   *           tree_extents_scrubbed: 30023
> > +   *           data_bytes_scrubbed: 4474441728
> > +   *           tree_bytes_scrubbed: 491896832
> > +   *           read_errors: 0
> > +   *           csum_errors: 0
> > +   *           verify_errors: 0
> > +   *           no_csum: 17760
> > +   *           csum_discards: 197622
> > +   *           super_errors: 0
> > +   *           malloc_errors: 0
> > +   *           uncorrectable_errors: 0
> > +   *           unverified_errors: 0
> > +   *           corrected_errors: 0
> > +   *           last_physical: 10301341696
> > +   *
> > +   * or:
> > +   *
> > +   *   scrub status for 346121d1-1847-40f8-9b7b-2bf3d539c68f
> > +   *           no stats available
> > +   */
> > +  for (i = 1; lines[i] != NULL; ++i) {
> > +    if ((i == 1) && STREQ (lines[i], "\tno stats available"))
> > +      return ret;
> > +    else if ((i == 2) && sscanf (lines[i], "\tdata_extents_scrubbed: %" SCNu64,
> > +                                 &ret->btrfsscrub_data_extents_scrubbed) != 1)
> > +      goto error;
> > +    else if ((i == 3) && sscanf (lines[i], "\ttree_extents_scrubbed: %" SCNu64,
> > +                                 &ret->btrfsscrub_tree_extents_scrubbed) != 1)
> > +      goto error;
> [etc]
> 
> In my previous comment[1], I said it's better to turn this into a
> loop, and that's what you've done.
> 
> [1] https://www.redhat.com/archives/libguestfs/2015-February/msg00008.html
> 
> Unfortunately testing `i == 2' etc means the loop isn't useful.  The
> code is effectively the same as the old code.  It's still fragile if
> the output of scrub status changes slightly.
> 
> I suggest removing the `i == X' tests.
> 

Will do.

Thanks,
- Chen

> Rest of the patch looks OK.
> 
> Rich.
> 
> --
> Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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