On 2020/1/13 8:44 下午, Jens-U. Mozdzen wrote: > Hi Coly, > > jumping in here, because I was looking for a way to revert from bcache > to plain device: > > Zitat von Coly Li <colyli@xxxxxxx>: >> The super block location of the backing disk is occupied by bcache. You >> cannot mount the file system directly from the backing disk which is >> formated as bcache backing device [...] (bcache offset all I/Os on >> bcache device 4KB behind the requesting >> LBA on backing disk). > > Assuming that no caching device is associated with a backing device (so > the backing device is "clean" as in "containing all data blocks with the > current content"), could one convert the content of a backing device to > a "non-bcached device" by removing the first 4096 octets of the backing > device content? > > Something like "dd if=backingdev of=newdev skip_bytes=4096 ..."? Hi Jens-U, you may try dmsetup to setup a linear device mapper target, and the map table just skipping the first 4KB (bcache superblock area). If you are lucky, I mean the real file system is not corrupted, the created device mapper target can be mounted directly. -- Coly Li
