Hello guys !
I have flash card /dev/sda. /dev/sda2 is ext3 partition with root, log is enabled. Initially root mounted in read only mode. If I need to change something, I remount to read write, change and remount back to read only. Recently I decide to use md5sum to be sure in my flash integrity, just calculate md5 for /dev/sda2 and compare at boot time. And I found very strange (at least for me) problem. I change some files in root and after do sync and echo 3 > /proc/sys/vm/drop_caches. As result content of /dev/sda2 and subset of /dev/sda must be equal, but it different in some bytes (mutated bytes). And subset of /dev/sda is real flash content, I will get it in /dev/sda2 after flash reconnect or reboot. It means the content of /dev/sda2 will change after reboot. I found the mutated bytes are located in ext3 journal unallocated blocks, so they are not used, but anyway virtual device data and corresponding phisical device data must be equal, and can't be changed by just reboot, isn't it ? This is true for latest stable kernel 3.16.1. I also found mutated bytes changes in physical device and remain unchanged (physical device old data) in corresponding virtual device. That is going on ? Is it ok ? Or may be this is very hard to catch important bug ? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
