On 10/27/11 2:13 AM, Akira Fujita wrote: > Hi, > > If all of the superblock and backup superblocks are corrupted, > mke2fs -S which reinitializes the superblock and > group descriptors only is a last resort to recover. > > However, on ext4, all of the files are lost with this way. > Because mke2fs -S for ext4 sets uninit_bg and then later e2fsck regards > all of block group as uninitialized one so that it can not recover > with bitmaps. > > Of course ext3 can recover all of the files with mke2fsk -S, > ext4 should be able to recover as well. > There is a avoidance (see #3 of the reproduce steps) > but an appropriate fix would be needed for e2fsck. > > * Reproduce steps and log are as follows: > My e2fprogs was e2fsprogs-1.42-WIP > > 1. mkfe2s -t ext4 /dev/sdaX > 2. create some files on ext4 > 3. mkfe2s -t ext4 -S -b 4096 /dev/sdaX > # This problem does not occur, > # when we remove uninit_bg feature flag (-O ^uninit_bg). It seems to me that the main bug here is that mkfs.ext4 should never mark blockgroups as uninit, when run with -S. Marking them uninit goes against the described "not touching the inode table and the block and inode bitmaps" behavior... -Eric > 4. e2fsck /dev/sdaX > > e2fsck 1.42-WIP (16-Oct-2011) > Backing up journal inode block information. > > /dev/sda8 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 > Root inode not allocated. Allocate<y>? yes > > /lost+found not found. Create<y>? yes > > Pass 4: Checking reference counts > Pass 5: Checking group summary information > Block bitmap differences: -(8483--8486) -(33026--33027) > Fix<y>? yes > > Free blocks count wrong for group #0 (24286, counted=24285). > Fix<y>? yes > > Free blocks count wrong (1030071, counted=1030070). > Fix<y>? yes > > Free inodes count wrong for group #0 (8191, counted=8190). > Fix<y>? yes > > Directories count wrong for group #0 (1, counted=2). > Fix<y>? yes > > Free inodes count wrong (262143, counted=262142). > Fix<y>? yes > > > /dev/sda8: ***** FILE SYSTEM WAS MODIFIED ***** > /dev/sda8: 2/262144 files (0.0% non-contiguous), 18506/1048576 blocks > > > As I reported before, e2fsck -b also can not recover with > backup superblock correctly. > # http://marc.info/?l=linux-ext4&m=131541543931429&w=2 > > Is there any ideas to fix these issues? > > Regards, > Akira Fujita > -- > 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
