On 12/13/16 9:39 AM, Heinz Nimmervoll wrote: > I still got no answer for my problem thats why I try it here... hopefully you could help me out. > > System: > > Embedded board with Atmel SAM9x25 > Debian Wheezy Kernel 3.11.6 > 32GB Samsung SDHC card with ext4 root- partition (journal activated) > > > After system running two weeks or so superblock from rootfs (ext4) at block 0 got overwritten with "trash data". > This is happening with like 20% of the embedded devices. > > hex comparision between faulty and good superblock starting at byte 1024: > > Before (good): > > 00000000 00 ee 02 00 00 b8 0b 00 00 96 00 00 ab a9 05 00 |................| > 00000010 c3 0c 02 00 00 00 00 00 02 00 00 00 02 00 00 00 |................| > 00000020 00 80 00 00 00 80 00 00 40 1f 00 00 9e 68 46 58 |........@....hFX| > 00000030 9e 68 46 58 2e 00 64 00 53 ef 01 00 01 00 00 00 |.hFX..d.S.......| <snip> > > After (corrupted): > > 00000000 00 00 00 00 a4 81 00 00 dd 00 00 00 24 8e 5d 54 |............$.]T| > 00000010 7e 8e 5d 54 18 a6 9f 41 00 00 00 00 00 00 01 00 |~.]T...A........| > 00000020 08 00 00 00 00 00 08 00 01 00 00 00 0a f3 01 00 |................| > 00000030 04 00 00 00 00 00 00 00 00 00 00 00 01 00 00 00 |................| <snip> > - How is it possible, that even the magic number (and everything else) got overwritten? > - Why could it ever be overwritten? I don't think anyone here can tell you what happened, it is almost certainly not an ext4 bug. Could be a driver bug, or an admin running a stray "dd" command, or some other utility gone astray, or ... anything, really. As a very long shot, what does "blkid" or "file -s" tell you about the block device after it's been overwritten? Perhaps it will recognize a signature. Otherwise, you could do something like a modified kernel to trap any IO to block zero on the device and issue a printk about the process which is doing it, filtering out any expected ext4 accesses. -Eric > Thank you so much! > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
