As Eric mentions, disabling mblk_io_submit makes this work. I've reproduced this on my system, and I'm testing a fix for it which I'll try to post tomorrow. It's limited to block size < page size partitions. Curt On Thu, Apr 21, 2011 at 11:27 AM, Jim Meyering <jim@xxxxxxxxxxxx> wrote: > Much like this report, > > loopback-mounted ext4 sees hole-filling (on rawhide, but not F15) > http://thread.gmane.org/gmane.comp.file-systems.ext4/24454 > > but not requiring that one remove the backing file, this script shows the > same sort of corruption with a loopback-ext4-in-loopback-ext4 file system: > [Note these FS are small enough that they get a blocksize of 1024 by default. > When I specify -b 2048 or 4096, the problem goes away. ] > > ============================================= > #!/bin/sh > set -e > dd if=/dev/zero of=blob bs=9k count=1000 >/dev/null 2>&1 > mkdir mnt > mkfs -q -t ext4 -F blob > mount -oloop blob mnt > > c1=$PWD > cd mnt > > dd if=/dev/zero of=blob bs=4k count=1000 >/dev/null 2>&1 > mkdir m2 > mkfs -q -t ext4 -F blob > mount -oloop blob m2 > > c2=$PWD > cd m2 > > # Create a reference file. Just like the following one, > # but with explicit NULs in place of holes. > perl -e '$n=1024; for (1..71) { print "\0"x$n, chr($_)x$n };' \ > -e 'close *STDOUT or die "$!"' > ref > > # Seek 1KB, write 1KB of data, seek 1KB, write 1KB of data, etc.... > perl -e '$n = 1 * 1024; *F = *STDOUT;' \ > -e 'for (1..71) { sysseek (*F, $n, 1)' \ > -e '&& syswrite (*F, chr($_)x$n) or die "$!"}' > j1 > > # filefrag -vs j1 > > sync > cmp -s ref j1 && fail=0 || fail=1 > > cd / > umount "$c2/m2" "$c1/mnt" > rm -rf "$c1/blob" "$c1/mnt" > > exit $fail > ============================================= > > This shows that it fails most of the time for me in tmpfs on a rawhide > guest (2.6.39-0.rc3.git2.0.fc16.x86_64) running on an F15 host. YMWV. > > $ while :; do ./ext4-bug; printf $?; done > 111111110111111110111111011111111110101111111111 > [Exit 130 (INT)] > -- > 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
