jffs2: directory rename and power-cut causes strange situation

[Ronald Wahl]

Hi,

I have experienced a strange behaviour on a jffs2 filesystem with a 
directory rename and power-cut. I have to admit that I have write 
buffering (and SUMMARY) enabled and it is a SPI-NOR flash with 
transparent ECC and a write buffer size of 16 bytes. Not sure if this 
matters but it makes the issue more reproducable I think. Kernel is 6.12.40.

Steps:
1. mkdir D
2. touch D/file
3. sync
4. mv D E
5. immediate power-cut
6. reboot and mount the filesystem

Observations:
1. Mounting will show some errors that might be expected:

    jffs2: jffs2_scan_dirent_node(): Name CRC failed on node at
      0x0007d81c: Read 0xffffffff, calculated 0x2d02ef8d
    jffs2: error: (575) jffs2_build_filesystem: child dir "D" (ino
      #20025) of dir ino #1 is also hard linked from dir ino #1

2. There are two directories D and E both referring to the same inode,
    i.e. a hardlink, which typically is not allowed to create with
    link() for good reasons

3. Removing one of the directories with "rm -rf D" will (not quite
    unexpected) and a subsequent "ls -l" cause jffs2 errors and ls fails:

    jffs2: warning: (1097) jffs2_get_inode_nodes: Eep. No valid nodes for
      ino #20025.
    jffs2: warning: (1097) jffs2_do_read_inode_internal: no data nodes
      found for ino #20025
    jffs2: iget() failed for ino #20025
    ls: ./E: Input/output error

So now the question is how to recover from this situation? Somehow 
hard-linked directories are something rather evil. Maybe this should be 
corrected during mount already?

Thx,
ron