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Message-ID: <c73ca48af09742318189c61d167c4459@SGPMBX1004.APAC.bosch.com>
Date: Wed, 6 Jan 2016 02:39:15 +0000
From: "HUANG Weller (CM/ESW12-CN)" <Weller.Huang@...bosch.com>
To: Jan Kara <jack@...e.cz>
CC: "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>
Subject: RE: ext4 out of order when use cfq scheduler
> So you are running in 'ws' mode of your tool, am I right? Just looking into the
> sources you've sent me I've noticed that although you set O_SYNC in openflg
> when mode == MODE_WS, you do not use openflg at all. So file won't be synced
> at all. That would well explain why you see that not all file contents is written. So
> did you just send me a different version of the source or is your test program
> really buggy?
>
Yes, it is a bug of the test code. So the test tool create files without O_SYNC flag actually.
But , even in this case, is the out of order acceptable ? or is it normal ?
>
> > > > [root@...Fatlas6 ~]# debugfs /dev/nandblk0p3 debugfs 1.42.9
> > > > (28-Dec-2013)
> > > > debugfs: imap test/hp0000017aMhWY3i0vMv Inode 390 is part of
> > > > block group 0
> > > > located at block 141, offset 0x0280
> > > >
> > > > 00000280 80 81 00 00 10 00 04 00 c8 09 00 00 66 0a 00 00
> > > > |............f...|
> > > > 00000290 66 0a 00 00 00 00 00 00 00 00 01 00 04 02 00 00
> > > > |f...............|
> > > > 000002a0 00 00 08 00 01 00 00 00 0a f3 02 00 04 00 00 00
> > > > |................|
> > > > 000002b0 00 00 00 00 00 00 00 00 80 00 00 00 00 2c 01 00
> > > > |.............,..| ==> the file contents is at 0x00012c00
> > > > 000002c0 80 00 00 00 01 00 00 00 8e 26 01 00 00 00 00 00
> > > > |.........&......|
> > > >
> > > >
> > > > Search the block number from the journal blocks:
> > > >
> > > > [root@...Fatlas6 ~]# hexdump j.bin -C | grep "00 2c 01 00"
> > > > 00039ab0 00 00 00 00 00 00 00 00 80 00 00 00 00 2c 01 00
> > > > |.............,..|
> > > >
> > > > Search file name which the file checksum is error in journal blocks:
> > > >
> > > > [root@...Fatlas6 ~]# hexdump j.bin -C | grep "3i0vMv" -B1
> > > > 00030c60 86 01 00 00 1c 00 14 01 68 70 30 30 30 30 30 31
> > > > |........hp000001|
> > > > 00030c70 37 61 4d 68 57 59 33 69 30 76 4d 76 88 01 00 00
> > > > |7aMhWY3i0vMv....|
> > > >
> > > >
> > > > List all journal block record to check which journal block records it:
> > > >
> > > > [root@...Fatlas6 ~]# hexdump j.bin -C | grep "c0 3b 39 98"
> > > > 00000000 c0 3b 39 98 00 00 00 04 00 00 00 00 00 00 08 00
> > > > |.;9.............|
> > > > 00000800 c0 3b 39 98 00 00 00 05 00 00 00 6f 00 00 00 24
> > > > |.;9........o...$|
> > > > 00001000 c0 3b 39 98 00 00 00 01 00 00 00 6f 00 00 00 75
> > > > |.;9........o...u|
> > > > 0000c800 c0 3b 39 98 00 00 00 02 00 00 00 6f 00 00 00 00
> > > > |.;9........o....|
> > > > 0000d000 c0 3b 39 98 00 00 00 01 00 00 00 70 00 00 00 65
> > > > |.;9........p...e|
> > > > 00016000 c0 3b 39 98 00 00 00 02 00 00 00 70 00 00 00 00
> > > > |.;9........p....|
> > > > 00016800 c0 3b 39 98 00 00 00 01 00 00 00 71 00 00 00 7c
> > > > |.;9........q...||
> > > > 00021000 c0 3b 39 98 00 00 00 02 00 00 00 71 00 00 00 00
> > > > |.;9........q....|
> > > > 00021800 c0 3b 39 98 00 00 00 01 00 00 00 72 00 00 00 82
> > > > |.;9........r....|
> > > > 0002d000 c0 3b 39 98 00 00 00 02 00 00 00 72 00 00 00 00
> > > > |.;9........r....|
> > > > 0002d800 c0 3b 39 98 00 00 00 01 00 00 00 73 00 00 00 88
> > > > |.;9........s....|
> > > ==>00039ab0 is in last block, the file name and the start block
> > > number are all recorded in the journals.
> > > > 0003a000 c0 3b 39 98 00 00 00 02 00 00 00 73 00 00 00 00
> > > > |.;9........s....|
> > > >
> > > >
> > > > Back to see the kernel log which it print all the block numbers:
> > > >
> > > > ...
> > > > ...
> > > > [ 46.222671] 244109 75277
> > > > [ 46.222693]
> > > > [ 46.272438] 244352 75520
> > > > [ 46.272460]
> > > > [ 46.348417] 238443 69611
> > > > [ 46.348438]
> > > > [ 46.349811] 244480 75648
> > > > [ 46.352287]
> > > > [ 46.404904] 244609 75777
> > > > [ 46.404926]
> > > > [ 46.454698] 244738 75906
> > > > [ 46.454719]
> > > > [ 46.505439] 244992 76160
> > > > [ 46.505459]
> > > > [ 46.557783] 245120 76288
> > > > [ 46.557804]
> > > > [ 46.610075] 245249 76417
> > > > [ 46.610096]
> > > > [ 46.660196] 245378 76546
> > > > [ 46.660219]
> > > > [ 46.709906] 201691 32859 ==> journal start is 32768, so the offset is 91,
> > > block size=2048, so, the offset address in the j.bin is 0x2d800
> > > > [ 46.709928] J [ 46.711233]
> > > > [ 46.740635] drop to 9v
> > > > [ 46.749540] 201716 32884
> > > > [ 46.749560] J S
> > > > [ 46.751039]
> > > > [ 46.753151] 245632 76800 ==> 76800 in hex is 0x012c00, it is the same
> start
> > > block of the file which checksum is error.
> > > > [ 46.755284]
> > > > nanddisk idle -> 1.
> > > > [ 46.800227] 6v irq-2
> > > >
> > > >
> > > > The j.bin offset 0x2d800
> > > >
> > > > 0002d800 c0 3b 39 98 00 00 00 01 00 00 00 73 00 00 00 88
> > > > |.;9........s....| ==>00039ab0 is in last block
> > > > 0003a000 c0 3b 39 98 00 00 00 02 00 00 00 73 00 00 00 00
> > > > |.;9........s....|
> > > >
> > > >
> > > > Normally, ext4 will first write the file contents, and then write
> > > > the journal and journal commit. Then after some delay, it will
> > > > write the meta data. So The journal blocks contains the meta data
> > > > of the file which the file contents already been written before.
> > > > But from above analysis, the journal sequence 0x73 already
> > > > contain the file
> > > > name(hp0000017aMhWY3i0vMv) and the start block number(76800). So
> > > > from the kernel log, the block
> > > > number(76800) should be available before the journal blocks but
> > > > NOT after it. It seems that there is out of order happen.
> > > >
> > > > Could you please help to check this issue ? or give a explanation
> > > > about it ? Many thanks.
> > > >
> > > > Best regards
> > > >
> > > > Weller HUANG
> > > >
> > > >
> > > > --
> > > > To unsubscribe from this list: send the line "unsubscribe linux-ext4"
> > > > in the body of a message to majordomo@...r.kernel.org More
> > > > majordomo info at http://vger.kernel.org/majordomo-info.html
> > > --
> > > Jan Kara <jack@...e.com>
> > > SUSE Labs, CR
>
>
>
> --
> Jan Kara <jack@...e.com>
> SUSE Labs, CR
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