Messages in this thread | | | Subject | [2.6.30 and later] file corruption on ext3 filesystem. | From | Tetsuo Handa <> | Date | Fri, 08 Jan 2010 11:54:24 +0900 |
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Hello.
I'm experiencing file corruption problem. Can somebody reproduce below result?
My environment: VMware Workstation 6.5.3 with 2CPUs / 512MB RAM. ext3 filesystem ( /dev/sda1 ) mounted on / .
2.6.33-rc3 ( http://I-love.SAKURA.ne.jp/tmp/config-2.6.33-rc3-ext3 ) 2.6.32.3 ( http://I-love.SAKURA.ne.jp/tmp/config-2.6.32.3-ext3 ) 2.6.31.11 ( http://I-love.SAKURA.ne.jp/tmp/config-2.6.31.11-ext3 ) 2.6.30.10
So far, I haven't succeeded to reproduce this problem for 2.6.29 and earlier. Maybe this problem exists in only 2.6.30 and later.
Steps to reproduce:
Compile below program using "gcc -Wall -O3 -o a.out".
---------- #include <stdio.h> #include <string.h> #include <unistd.h>
int main(int argc, char *argv[]) { FILE *fp = fopen("/testfile", "a"); char buffer[4096]; memset(buffer, argc > 1 ? argv[1][0] : 0x20, sizeof(buffer)); buffer[sizeof(buffer) - 1] = '\n'; fwrite(buffer, 1, sizeof(buffer), fp); fflush(fp); sleep(5); fprintf(stderr, "Let power fail after a few seconds.\n"); while (1) { sleep(1); fwrite(buffer, 1, sizeof(buffer), fp); } return 0; } ----------
Reboot the system by executing /sbin/reboot .
Run ./a.out and let the power fail (i.e. unplug the electric cable or do equivalent) after more than 5 seconds (i.e. longer than kjournald's commit interval). Probably 2 or 3 seconds after "Let power fail after a few seconds.\n" was printed is the best.
Restart the system (and fsck will be executed).
Run "cat /testfile". It should contain only lines of 4095 spaces + '\n' (or the byte specified via argv[]). But it contains different data.
This problem does not show up if the data written by ./a.out and the data in previously deleted files are identical. Therefore, you may want to try with different patterns like "./a.out 1" "./a.out 2" "./a.out 3" ...
Regards.
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