Date: Tue, 25 Jan 2011 18:33:03 +0200 From: Alexander Motin <mav@FreeBSD.org> To: John Baldwin <jhb@freebsd.org> Cc: svn-src-projects@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r217828 - projects/graid/head/sys/geom/raid Message-ID: <4D3EFB3F.8020508@FreeBSD.org> In-Reply-To: <201101251117.49069.jhb@freebsd.org> References: <201101251534.p0PFY7cF039182@svn.freebsd.org> <201101251117.49069.jhb@freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On 25.01.2011 18:17, John Baldwin wrote: > 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) >> +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? Actually I've also thought about it. It is trivial to use static variable in this particular place. But transformation modules (RAID0/RAID1/...) are also allocating some BIOs via g_clone_bio() and there it can be more difficult to fix, as several BIOs are allocated same time to fulfill original request. When testing with minidump enabled I've noticed errors about attempts to write after the dump device end. Is it unavoidable consequence of these allocations? -- Alexander Motin
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4D3EFB3F.8020508>