On 2018/9/14 上午12:37, Nikolay Borisov wrote: > > > On 13.09.2018 19:15, Serhat Sevki Dincer wrote: >>> -1 seems to be EPERM, is your device write-protected, readonly or >>> something like that ? >> >> I am able to use ext4 partition read/write, created a file and wrote >> in it, un/re mounted it, all is ok. >> The drive only has a microusb port and a little led light; no rw >> switch or anything like that.. >> > > What might help is running btrfs convert under strace. So something like : > > sudo strace -f -o strace.log btrfs-convert /dev/sdb1 and then send the log. > strace would greatly help in this case. My guess is something wrong happened in migrate_super_block(), which doesn't handle ret > 0 case well. In that case, it means pwrite 4K doesn't finish in one call, which looks pretty strange. Thanks, Qu
