Re: [PATCH 2/4] xfsrestore: fix on-media inventory stream unpacking

["Darrick J. Wong" <djwong@kernel.org>]

On Fri, Oct 14, 2022 at 03:15:33PM +1100, Donald Douwsma wrote:
> 
> 
> On 14/10/2022 14:37, Donald Douwsma wrote:
> > 
> > 
> > On 14/10/2022 06:05, Darrick J. Wong wrote:
> > > On Thu, Oct 13, 2022 at 02:15:16PM +1100, Donald Douwsma wrote:
> > > > xfsdump can create multiple streams, when restoring the online inventory
> > > > with multiple streams we fail to process these and assert when the
> > > > inventory buffer is not fully decoded.
> > > > 
> > > > [root@rhel8 ~]# xfsdump -L "Test1" -f /dev/nst0 -M tape1 -f
> > > > /dev/nst1 -M tape2 /boot
> > > > xfsdump: using scsi tape (drive_scsitape) strategy
> > > > xfsdump: using scsi tape (drive_scsitape) strategy
> > > > xfsdump: version 3.1.8 (dump format 3.0) - type ^C for status
> > > > and control
> > > > xfsdump: level 0 dump of rhel8:/boot
> > > > xfsdump: dump date: Thu Oct  6 13:50:45 2022
> > > > xfsdump: session id: aa25fa48-4493-45c7-9027-61e53e486445
> > > > xfsdump: session label: "Test1"
> > > > xfsdump: ino map phase 1: constructing initial dump list
> > > > xfsdump: ino map phase 2: skipping (no pruning necessary)
> > > > xfsdump: ino map phase 3: identifying stream starting points
> > > > xfsdump: stream 0: ino 133 offset 0 to ino 28839 offset 0
> > > > xfsdump: stream 1: ino 28839 offset 0 to end
> > > > xfsdump: ino map construction complete
> > > > xfsdump: estimated dump size: 328720704 bytes
> > > > xfsdump: estimated dump size per stream: 164375728 bytes
> > > > xfsdump: /var/lib/xfsdump/inventory created
> > > > xfsdump: drive 0: preparing drive
> > > > xfsdump: drive 1: preparing drive
> > > > xfsdump: drive 1: creating dump session media file 0 (media 0, file 0)
> > > > xfsdump: drive 1: dumping ino map
> > > > xfsdump: drive 1: dumping non-directory files
> > > > xfsdump: drive 0: creating dump session media file 0 (media 0, file 0)
> > > > xfsdump: drive 0: dumping ino map
> > > > xfsdump: drive 0: dumping directories
> > > > xfsdump: drive 0: dumping non-directory files
> > > > xfsdump: drive 1: ending media file
> > > > xfsdump: drive 1: media file size 166723584 bytes
> > > > xfsdump: drive 1: waiting for synchronized session inventory dump
> > > > xfsdump: drive 0: ending media file
> > > > xfsdump: drive 0: media file size 165675008 bytes
> > > > xfsdump: drive 0: waiting for synchronized session inventory dump
> > > > xfsdump: drive 0: dumping session inventory
> > > > xfsdump: drive 0: beginning inventory media file
> > > > xfsdump: drive 0: media file 1 (media 0, file 1)
> > > > xfsdump: drive 0: ending inventory media file
> > > > xfsdump: drive 0: inventory media file size 2097152 bytes
> > > > xfsdump: drive 0: writing stream terminator
> > > > xfsdump: drive 0: beginning media stream terminator
> > > > xfsdump: drive 0: media file 2 (media 0, file 2)
> > > > xfsdump: drive 0: ending media stream terminator
> > > > xfsdump: drive 0: media stream terminator size 1048576 bytes
> > > > xfsdump: drive 1: dumping session inventory
> > > > xfsdump: drive 1: beginning inventory media file
> > > > xfsdump: drive 1: media file 1 (media 0, file 1)
> > > > xfsdump: drive 1: ending inventory media file
> > > > xfsdump: drive 1: inventory media file size 2097152 bytes
> > > > xfsdump: drive 1: writing stream terminator
> > > > xfsdump: drive 1: beginning media stream terminator
> > > > xfsdump: drive 1: media file 2 (media 0, file 2)
> > > > xfsdump: drive 1: ending media stream terminator
> > > > xfsdump: drive 1: media stream terminator size 1048576 bytes
> > > > xfsdump: dump size (non-dir files) : 328189016 bytes
> > > > xfsdump: dump complete: 4 seconds elapsed
> > > > xfsdump: Dump Summary:
> > > > xfsdump:   stream 0 /dev/nst0 OK (success)
> > > > xfsdump:   stream 1 /dev/nst1 OK (success)
> > > > xfsdump: Dump Status: SUCCESS
> > > > [root@rhel8 ~]# xfsdump -I
> > > > file system 0:
> > > >     fs id:        26dd5aa0-b901-4cf5-9b68-0c5753cb3ab8
> > > >     session 0:
> > > >         mount point:    rhel8:/boot
> > > >         device:        rhel8:/dev/sda1
> > > >         time:        Thu Oct  6 13:50:45 2022
> > > >         session label:    "Test1"
> > > >         session id:    aa25fa48-4493-45c7-9027-61e53e486445
> > > >         level:        0
> > > >         resumed:    NO
> > > >         subtree:    NO
> > > >         streams:    2
> > > >         stream 0:
> > > >             pathname:    /dev/nst0
> > > >             start:        ino 133 offset 0
> > > >             end:        ino 28839 offset 0
> > > >             interrupted:    NO
> > > >             media files:    2
> > > >             media file 0:
> > > >                 mfile index:    0
> > > >                 mfile type:    data
> > > >                 mfile size:    165675008
> > > >                 mfile start:    ino 133 offset 0
> > > >                 mfile end:    ino 28839 offset 0
> > > >                 media label:    "tape1"
> > > >                 media id:    adb31f2a-f026-4597-a20a-326f28ecbaf1
> > > >             media file 1:
> > > >                 mfile index:    1
> > > >                 mfile type:    inventory
> > > >                 mfile size:    2097152
> > > >                 media label:    "tape1"
> > > >                 media id:    adb31f2a-f026-4597-a20a-326f28ecbaf1
> > > >         stream 1:
> > > >             pathname:    /dev/nst1
> > > >             start:        ino 28839 offset 0
> > > >             end:        ino 1572997 offset 0
> > > >             interrupted:    NO
> > > >             media files:    2
> > > >             media file 0:
> > > >                 mfile index:    0
> > > >                 mfile type:    data
> > > >                 mfile size:    166723584
> > > >                 mfile start:    ino 28839 offset 0
> > > >                 mfile end:    ino 1572997 offset 0
> > > >                 media label:    "tape2"
> > > >                 media id:    22224f02-b6c7-47d5-ad61-a61ba071c8a8
> > > >             media file 1:
> > > >                 mfile index:    1
> > > >                 mfile type:    inventory
> > > >                 mfile size:    2097152
> > > >                 media label:    "tape2"
> > > >                 media id:    22224f02-b6c7-47d5-ad61-a61ba071c8a8
> > > > xfsdump: Dump Status: SUCCESS
> > > > [root@rhel8 ~]# mv /var/lib/xfsdump/inventory
> > > > /var/lib/xfsdump/inventory_two_sessions
> > > > [root@rhel8 ~]# xfsdump -I
> > > > xfsdump: Dump Status: SUCCESS
> > > > 
> > > > [root@rhel8 ~]# xfsrestore -L Test1 -f /dev/nst0 /tmp/test1/
> > > > xfsrestore: using scsi tape (drive_scsitape) strategy
> > > > xfsrestore: version 3.1.8 (dump format 3.0) - type ^C for status
> > > > and control
> > > > xfsrestore: searching media for dump
> > > > xfsrestore: preparing drive
> > > > xfsrestore: examining media file 2
> > > > xfsrestore: found dump matching specified label:
> > > > xfsrestore: hostname: rhel8
> > > > xfsrestore: mount point: /boot
> > > > xfsrestore: volume: /dev/sda1
> > > > xfsrestore: session time: Thu Oct  6 13:50:45 2022
> > > > xfsrestore: level: 0
> > > > xfsrestore: session label: "Test1"
> > > > xfsrestore: media label: "tape1"
> > > > xfsrestore: file system id: 26dd5aa0-b901-4cf5-9b68-0c5753cb3ab8
> > > > xfsrestore: session id: aa25fa48-4493-45c7-9027-61e53e486445
> > > > xfsrestore: media id: adb31f2a-f026-4597-a20a-326f28ecbaf1
> > > > xfsrestore: searching media for directory dump
> > > > xfsrestore: rewinding
> > > > xfsrestore: examining media file 0
> > > > xfsrestore: reading directories
> > > > xfsrestore: 9 directories and 320 entries processed
> > > > xfsrestore: directory post-processing
> > > > xfsrestore: restoring non-directory files
> > > > xfsrestore: examining media file 1
> > > > xfsrestore: inv_stobj.c:1119: stobj_unpack_sessinfo: Assertion
> > > > `(size_t) ( p - (char *) bufp ) == bufsz' failed.
> > > > Aborted (core dumped)
> > > > 
> > > > Make sure we unpack multiple streams when restoring the online
> > > > inventory from media.
> > > > 
> > > > Signed-off-by: Donald Douwsma <ddouwsma@redhat.com>
> > > 
> > > Much better now, though I hope there's an fstest coming to make sure
> > > that multistream restore/dump work properly.
> > 
> > That could be a little tricky.
> > 
> > xfstests currently only supports one TAPE_DEV (and a remote
> > RMT_TAPE_DEV). So we'd need to add support for multiple tapes,
> > something like
> 
> Thinking about this some more RMT_TAPE_DEV may be ok. If streaming to
> multiple targets is meant to enable an offsite dump it could be done
> via remote i.e.
> 
> # xfsdump -L "Test3" -f /dev/nst0 -M "tape1" -f backup.example.com:/dev/nst0
> -M "tape2" /
> 
> The existing remote tests xfs/037 and xfs/038 just use the device for a
> simple backup.
> 
> Or I could be inventing a never useful use case.

I wonder, does the "remote" tape device have to be remote, or is xfsdump
flexible enough to let you set up a dummy file to dump into?

I bet any fstest that actually requires a real tape device hasn't been
run in years, except maybe by the RH QA department. :/

--D

> Don
> 
> > 
> > TAPE_DEV1=/dev/nst0
> > TAPE_DEV2=/dev/nst1
> > 
> > Then it can be hard to get access to a tape drive, let alone two.
> > 
> > Probably the easiest way to address that is to provide instructions on
> > how to setup mhvtl, https://github.com/markh794/mhvtl and load the
> > tapes before a test run with
> > 
> > [root@rhel8 ~]# systemctl start mhvtl.target
> > [root@rhel8 ~]# mtx -f /dev/sch0 load 1 0; mtx -f /dev/sch load 2 1
> > Loading media from Storage Element 1 into drive 0...done
> > Loading media from Storage Element 2 into drive 1...done
> > [root@rhel8 ~]# ./check -g xfs/tape
> > 
> > Not sure there's many people who test the tape group, so this may be
> > generally useful.
> > 
> > mhvtl requires a kernel module to be built, not sure if that would
> > bother QE folk when doing general tests, but for xfsdump userspace
> > testing it should be fine.
> > 
> > Don
> > 
> > 
> > > Reviewed-by: Darrick J. Wong <djwong@kernel.org>
> > > 
> > > --D
> > > 
> > > > ---
> > > >   inventory/inv_stobj.c | 13 +++++++------
> > > >   1 file changed, 7 insertions(+), 6 deletions(-)
> > > > 
> > > > diff --git a/inventory/inv_stobj.c b/inventory/inv_stobj.c
> > > > index b461666..025d431 100644
> > > > --- a/inventory/inv_stobj.c
> > > > +++ b/inventory/inv_stobj.c
> > > > @@ -1065,25 +1065,26 @@ stobj_unpack_sessinfo(
> > > >           return BOOL_FALSE;
> > > >       }
> > > > +    /* get the seshdr and then, the remainder of the session */
> > > >       xlate_invt_seshdr((invt_seshdr_t *)p, (invt_seshdr_t *)tmpbuf, 1);
> > > >       bcopy(tmpbuf, p, sizeof(invt_seshdr_t));
> > > > -
> > > > -    /* get the seshdr and then, the remainder of the session */
> > > >       s->seshdr = (invt_seshdr_t *)p;
> > > >       s->seshdr->sh_sess_off = -1;
> > > >       p += sizeof(invt_seshdr_t);
> > > > -
> > > >       xlate_invt_session((invt_session_t *)p, (invt_session_t
> > > > *)tmpbuf, 1);
> > > >       bcopy (tmpbuf, p, sizeof(invt_session_t));
> > > >       s->ses = (invt_session_t *)p;
> > > >       p += sizeof(invt_session_t);
> > > >       /* the array of all the streams belonging to this session */
> > > > -    xlate_invt_stream((invt_stream_t *)p, (invt_stream_t *)tmpbuf, 1);
> > > > -    bcopy(tmpbuf, p, sizeof(invt_stream_t));
> > > >       s->strms = (invt_stream_t *)p;
> > > > -    p += s->ses->s_cur_nstreams * sizeof(invt_stream_t);
> > > > +    for (i = 0; i < s->ses->s_cur_nstreams; i++) {
> > > > +        xlate_invt_stream((invt_stream_t *)p,
> > > > +                  (invt_stream_t *)tmpbuf, 1);
> > > > +        bcopy(tmpbuf, p, sizeof(invt_stream_t));
> > > > +        p += sizeof(invt_stream_t);
> > > > +    }
> > > >       /* all the media files */
> > > >       s->mfiles = (invt_mediafile_t *)p;
> > > > -- 
> > > > 2.31.1
> > > > 
> > > 
>