Hi Dave, We export a container image file as a block device via loop device, but we found it's very easy that the container rootfs gets corrupted due to power loss. Your early version of loop-aio patchset said the patchset can make loop mounted filesystems recoverable(lkml.org/lkml/2012/3/30/317), but we found it doesn't help. Both the guest fs and host fs are ext3. The loop-aio patchset is from: git://github.com/kleikamp/linux-shaggy.git aio_loop Steps: 1. dd a 10G image, mkfs.ext3, # dd if=/dev/zero of=./raw_image bs=1M count=10000 # echo y | mkfs.ext3 raw_image 2. losetup a loop device, mount at ./test_dir # losetup /dev/loop1 raw_image # mount /dev/loop1 ./test_dir 3. copy fs_mark into test_dir and run # ./fs_mark -d ./tmp/ -s 102400000 -n 80 4. during runing fs_mark, make systerm reboot indirectly. # echo b > /proc/sysrq-trigger After systerm booted up, sometimes fsck reported raw_image fs has been damaged. # fsck.ext3 -n raw_image e2fsck 1.41.9 (22-Aug-2009) Warning: skipping journal recovery because doing a read-only filesystem check. raw_image contains a file system with errors, check forced. Pass 1: Checking inodes, blocks, and sizes Pass 2: Checking directory structure Pass 3: Checking directory connectivity Pass 4: Checking reference counts Pass 5: Checking group summary information Free blocks count wrong (2481348, counted=2480577). Fix? no Free inodes count wrong (640837, counted=640835). Fix? no raw_image: ********** WARNING: Filesystem still has errors ********** raw_image: 11/640848 files (0.0% non-contiguous), 78652/2560000 blocks With a specific script, I can almost 100% reproduce this issue. And it seems the corruption can only happen when reboot happens at the time loop is calling vfs_fsync(). Do you have any idea why the loop-aio patchset doesn't help? Thanks. -- 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
