Re: Mount corrupts an ext2 filesystem on a RAM disk

[Maurice Volaski <mvolaski@aecom.yu.edu>]

And in pre-5. Marcelo, I have never seen any feedback on this bug report.

>>Problem is still present in in 2.4.19-pre4.
>>
>>>I just tried 2.4.19-pre3 and it seems to suffer the same problem..
>>>
>>>I have also learned that is necessary to do an "ls" on the ram 
>>>filesystem to actually cause the damage. Simply mounting and 
>>>unmounting doesn't do any damage.
>>>
>>>>Subject: Mount corrupts an ext2 filesystem on a RAM disk
>>>>Cc: mkcdrec-users@lists.sourceforge.net
>>>>Bcc:
>>>>X-Attachments:
>>>>
>>>>(All this was done on a RedHat 7.1 system with kernel 2.4.18 and 
>>>>mount-2.11n-7. The problem does not happen on a RedHat 7.1 system 
>>>>with kernel 2.4.17. )
>>>>
>>>>The following was discovered attempting to use mkcdrec to make a backup.
>>>>
>>>>I do the following to setup a ram disk on /dev/ram0...
>>>>
>>>>dd if=/dev/zero of=/dev/ram0 bs=1k count=4096
>>>>mkfs.ext2 /dev/ram0 -m 0 -N 4096
>>>>
>>>>This ram disk checks OK with fsck -f.
>>>>
>>>>I mount it and already the lost+found directory is not there.
>>>>
>>>>If unmount and force fsck, I get...
>>>>
>>>>fsck 1.25 (20-Sep-2001)
>>>>e2fsck 1.25 (20-Sep-2001)
>>>>Pass 1: Checking inodes, blocks, and sizes
>>>>Duplicate blocks found... invoking duplicate block passes.
>>>>Pass 1B: Rescan for duplicate/bad blocks
>>>>Duplicate/bad block(s) in inode 2: 52
>>>>Pass 1C: Scan directories for inodes with dup blocks.
>>>>Pass 1D: Reconciling duplicate blocks
>>>>(There are 1 inodes containing duplicate/bad blocks.)
>>>>
>>>>File / (inode #2, mod time Fri Mar  1 21:03:59 2002)
>>>>   has 1 duplicate block(s), shared with 1 file(s):
>>>>         <filesystem metadata>
>>>>Clone duplicate/bad blocks<y>? yes
>>>>
>>>>Pass 2: Checking directory structure
>>>>Directory inode 2, block 0, offset 0: directory corrupted
>>>>Salvage<y>? yes
>>>>
>>>>Missing '.' in directory inode 2.
>>>>Fix<y>? yes
>>>>
>>>>Setting filetype for entry '.' in ??? (2) to 2.
>>>>Missing '..' in directory inode 2.
>>>>Fix<y>? yes
>>>>
>>>>Setting filetype for entry '..' in ??? (2) to 2.
>>>>Pass 3: Checking directory connectivity
>>>>'..' in / (2) is <The NULL inode> (0), should be / (2).
>>>>Fix<y>? yes
>>>>
>>>>Unconnected directory inode 11 (/???)
>>>>Connect to /lost+found<y>? yes
>>>>
>>>>/lost+found not found.  Create<y>? yes
>>>>
>>>>Pass 4: Checking reference counts
>>>>Inode 2 ref count is 10, should be 3.  Fix<y>? yes
>>>>
>>>>Inode 11 ref count is 3, should be 2.  Fix<y>? yes
>>>>
>>>>Pass 5: Checking group summary information
>>>>Free blocks count wrong for group #0 (3566, counted=3565).
>>>>Fix<y>? yes
>>>>
>>>>Free blocks count wrong (3566, counted=3565).
>>>>Fix<y>? yes
>>>>
>>>>Free inodes count wrong for group #0 (4085, counted=4084).
>>>>Fix<y>? yes
>>>>
>>>>Directories count wrong for group #0 (2, counted=3).
>>>>Fix<y>? yes
>>>>
>>>>Free inodes count wrong (4085, counted=4084).
>>>>Fix<y>? yes
>>>>
>If I mount the disk, lost+found is still missing. If I unmount and 
>force fsck, I get the same result above.

-- 

Maurice Volaski, mvolaski@aecom.yu.edu
Computing Support, Rose F. Kennedy Center
Albert Einstein College of Medicine of Yeshiva University