Date: Sun, 8 Dec 2013 17:55:46 +0100 From: Gyrd Thane Lange <gyrd-se@thanelange.no> To: Olivier =?UTF-8?B?Q29jaGFyZC1MYWJiw6k=?= <olivier@cochard.me> Cc: "freebsd-current@freebsd.org" <freebsd-current@freebsd.org> Subject: Re: Regression on -current with mdconfig or dd Message-ID: <20131208175546.2a7815ad@onyx.thanelange.no> In-Reply-To: <CA%2Bq%2BTcr0DVRm%2BV81RutFg_UU5TQshUfgvNd%2B7=_0KKdDdNZxoQ@mail.gmail.com> References: <CA%2Bq%2BTcr0DVRm%2BV81RutFg_UU5TQshUfgvNd%2B7=_0KKdDdNZxoQ@mail.gmail.com>
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On Sun, 8 Dec 2013 15:50:55 +0100 Olivier Cochard-Labbé <olivier@cochard.me> wrote: > Hi, > > I found a regression on current: > The problem is meet with dd but I'm not sure it's the root cause. > > Here is how to reproduce the problem easily with 3 commands: > > dd if=/dev/zero of=/tmp/SOURCE.img seek=100000 count=0 > mdconfig -a -t vnode -f /tmp/SOURCE.img > dd conv=sparse if=/dev/md0 of=/tmp/DEST.img bs=64k > > => This last "dd" works great on 10.0-BETA3 and older but failed on > -current (r258675 and r259096) with the message: > dd: /dev/md0s1: Input/output error Hi, I can confirm this problem also exists on my 11-CURRENT (late november). It is not md-specific as I also see it with real disks: This example is from a partition that is exactly 34 sectors large. (512 sector size). [root@onyx ~]# dd if=/dev/ada2p9 | hd 00000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * dd: /dev/ada2p9: Input/output error 35+0 records in 35+0 records out 17920 bytes transferred in 0.269167 secs (66576 bytes/sec) 00004600 But still it tries to overshoot and read size+1 sectors. BTW I don't know where it gets the data for the last sector since the partition following this has non-zero data in its first sector but dd thinks it got a zero filled sector. On my other system, FreeBSD 8.3 the dd gets this right by copying exactly 34 sectors (even if I try to specify count=35 or larger). An even shorter method of reproducing is to create a 34 * 512 = 17408 byte memory backed device and read from it: # mdconfig -a -t malloc -s 34 -u 1 # dd if=/dev/md1 of=/dev/null dd: /dev/md1: Input/output error 35+0 records in 35+0 records out 17920 bytes transferred in 0.000354 secs (50614093 bytes/sec) Try to write to it: # dd if=/dev/zero of=/dev/md1 dd: /dev/md1: Input/output error 36+0 records in 35+0 records out 17920 bytes transferred in 0.000459 secs (39045157 bytes/sec) Where does it write the data to? (Have not dared to try on a real disk yet.) Gyrd ^_^ > > Regards, > > Olivier > _______________________________________________ > freebsd-current@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to > "freebsd-current-unsubscribe@freebsd.org"
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