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

[Donald Douwsma <ddouwsma@redhat.com>]

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

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
>>
>