On 7/27/22 06:01, Milan Broz wrote: > Hi, > > We switched to using BLKZEROOUT ioctl in libcryptsetup, and now we see a > lot of messages like > > : operation not supported error, dev loop1, sector 0 op > 0x9:(WRITE_ZEROES) flags 0x8000800 phys_seg 0 prio class 0 > > But the operation succeeds (ioctl returns 0). > > As it seems, this happens when a loop device is allocated over a file on > NFS mounted directory. > Easy to reproduce (5.19-rc8) by doing this in NFS mounted dir: > > # truncate -s 1M test.img > # losetup /dev/loop1 test.img > # fallocate -zn -l 1048576 /dev/loop1 > > > Shouldn't the block layer be quiet here and just switch to a different > wipe method? > (I think it happens in other cases.) without having all the setup details when underlying controller advertises the it does support write-zeroes and then when actual command fails you should this message. In case device doesn't support the write-zeroes then block layer silently executes the emulation path that REQ_OP_WRITE with zeored out pages. > > It is perhaps just a benign message, but it can trigger some reports. > > Milan >
