svn commit: r217828 - projects/graid/head/sys/geom/raid

[Attilio Rao]

2011/1/25 John Baldwin <jhb at freebsd.org>:
> On Tuesday, January 25, 2011 10:34:07 am Alexander Motin wrote:
>> Author: mav
>> Date: Tue Jan 25 15:34:07 2011
>> New Revision: 217828
>> URL: http://svn.freebsd.org/changeset/base/217828
>>
>> Log:
>>   Implement kernel dumping to geom_raid volumes. Dumping mechanism supports
>>   any RAID levels without any additional magic. Dumping to RAID0 and RAID1
>>   verified to work right now.
>>
>> Modified:
>>   projects/graid/head/sys/geom/raid/g_raid.c
>>   projects/graid/head/sys/geom/raid/g_raid.h
>>   projects/graid/head/sys/geom/raid/md_intel.c
>>
>> Modified: projects/graid/head/sys/geom/raid/g_raid.c
>>
> ==============================================================================
>> --- projects/graid/head/sys/geom/raid/g_raid.c        Tue Jan 25 15:18:10 2011
> (r217827)
>> +++ projects/graid/head/sys/geom/raid/g_raid.c        Tue Jan 25 15:34:07 2011
> (r217828)
>> @@ -116,8 +116,10 @@ static int g_raid_update_subdisk(struct
>>  static int g_raid_update_volume(struct g_raid_volume *vol, u_int state);
>>  static void g_raid_dumpconf(struct sbuf *sb, const char *indent,
>>      struct g_geom *gp, struct g_consumer *cp, struct g_provider *pp);
>> +static void g_raid_start(struct bio *bp);
>>  static void g_raid_start_request(struct bio *bp);
>>  static void g_raid_disk_done(struct bio *bp);
>> +static void g_raid_poll(struct g_raid_softc *sc);
>>
>>  static const char *
>>  g_raid_disk_state2str(int state)
>> @@ -714,6 +716,73 @@ g_raid_unidle(struct g_raid_volume *vol)
>>  }
>>
>>  static void
>> +g_raid_dumpdone(struct bio *bp)
>> +{
>> +
>> +     bp->bio_flags |= BIO_DONE;
>> +}
>> +
>> +static int
>> +g_raid_dump(void *arg,
>> +    void *virtual, vm_offset_t physical, off_t offset, size_t length)
>> +{
>> +     struct g_raid_softc *sc;
>> +     struct g_raid_volume *vol;
>> +     struct bio *bp;
>> +
>> +     vol = (struct g_raid_volume *)arg;
>> +     sc = vol->v_softc;
>> +     G_RAID_DEBUG(3, "Dumping at off %llu len %llu.",
>> +         (long long unsigned)offset, (long long unsigned)length);
>> +
>> +     bp = g_alloc_bio();
>> +     bp->bio_cmd = BIO_WRITE;
>> +     bp->bio_done = g_raid_dumpdone;
>> +     bp->bio_attribute = NULL;
>> +     bp->bio_offset = offset;
>> +     bp->bio_length = length;
>> +     bp->bio_data = virtual;
>> +     bp->bio_to = vol->v_provider;
>> +
>> +     g_raid_start(bp);
>> +
>> +     while (!(bp->bio_flags & BIO_DONE)) {
>> +             G_RAID_DEBUG(4, "Poll...");
>> +             g_raid_poll(sc);
>> +             DELAY(10);
>> +     }
>> +
>> +     G_RAID_DEBUG(3, "Dumping at off %llu len %llu done.",
>> +         (long long unsigned)offset, (long long unsigned)length);
>> +
>> +     g_destroy_bio(bp);
>> +     return (0);
>> +}
>
> Hmm, so this allocates bio's to make the dump work.  I believer other dump
> routines in other drivers do not do this, but instead use pre-allocated
> commands to schedule dump I/O requests.  Would it be possible to pre-allocate
> the bio that is used here when dumping is enabled and reuse it for each
> g_raid_dump() call without free'ing it when the I/O is finished?

Yes, I'd really support this as well.
Having BIOs allocation in progress makes the dumping less robust than
it should be (yeah, the discussion is much longer than that, but
anyway...).

Attilio


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