Hello, I was trying to determine how btrfs reacts to disk errors, when I discovered, that flipping two Bytes, supposedly inside of a file can render the filesystem unusable. Here is what I did:
1. dd if=/dev/zero of=/dev/sdg2 bs=1M 2. mkfs.btrfs /dev/sdg2 3. mount /dev/sdg2 /tmp/btrfs 4. echo "hello world this is some text" > /tmp/btrfs/hello 5. umount /dev/sdg2 this should result in this image [1] in the following steps /dev/sdg2 is altered. Basically, we want to apply s/world/wirld/g 6. dd if=/dev/sdg2 of=/tmp/sdg2 bs=1M 7. edit /tmp/sdg2 in ghex, find & replace all occurences of "world" with "wirld" (two occurences found), save as /tmp/sdg2_new 8. dd if=/tmp/sdg2_new of=/dev/sdg2 bs=1M /dev/sdg2 now looks like this [2] now, when I try mounting /dev/sdg2: """22:21 root@localhost ~# LANG=EN mount /dev/sdg2 /tmp/btrfs/ mount: mount /dev/sdg2 on /tmp/btrfs failed: Cannot allocate memory""" ok, so let us try btrfs check """22:21 root@localhost ~# LANG=EN btrfs check /dev/sdg2 checksum verify failed on 4222976 found F22E71BD wanted CE334502 checksum verify failed on 4222976 found F22E71BD wanted CE334502 Csum didn't match Checking filesystem on /dev/sdg2 UUID: ea2843f1-e8aa-420f-acf8-6ef13f6c6753 checking extents Speicherzugriffsfehler (Speicherabzug geschrieben)""" that last line reads "Segfault, memory dumped". Is this behaviour expected? Kind regards, Niklas [1] tgz: https://gigamove.rz.rwth-aachen.de/d/id/R5CKikxbYTBdqs raw: https://gigamove.rz.rwth-aachen.de/d/id/VgMXAicS7CGEjt [2] tgz: https://gigamove.rz.rwth-aachen.de/d/id/cEebNYne9ppFy4 raw: https://gigamove.rz.rwth-aachen.de/d/id/ATJa7wpfEWdfL2 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
