Dealing with ReiserFS bad blocks
The following is a procedure for recovering a ReiserFS filesystem with bad blocks. If this is a system FS and cannot be unmounted, the box needs to be booted from the latest version of Knoppix Live CD that has ReiserFS tools available.
Determine the blocksize for your device (default is 4096):
debugreiserfs | grep -i 'blocksize'
Scan the device and record a list of bad blocks:
badblocks -n -b 4096 -o badblocksfile
Fix whatever can be fixed and mark the rest of the bad blocks as unusable:
reiserfsck --fix-fixable --badblocks badblocksfile