Re: [dm-devel] [PATCH v2 0/3] Fix dm-crypt zoned block device support

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 




On Sat, 17 Apr 2021, Damien Le Moal wrote:

> Mike,
> 
> Zone append BIOs (REQ_OP_ZONE_APPEND) always specify the start sector
> of the zone to be written instead of the actual location sector to
> write. The write location is determined by the device and returned to
> the host upon completion of the operation.

I'd like to ask what's the reason for this semantics? Why can't users of 
the zoned device supply real sector numbers?

> This interface, while simple and efficient for writing into sequential
> zones of a zoned block device, is incompatible with the use of sector
> values to calculate a cypher block IV. All data written in a zone is
> encrypted using an IV calculated from the first sectors of the zone,
> but read operation will specify any sector within the zone, resulting
> in an IV mismatch between encryption and decryption. Reads fail in that
> case.

I would say that it is incompatible with all dm targets - even the linear 
target is changing the sector number and so it may redirect the write 
outside of the range specified in dm-table and cause corruption.

Instead of complicating device mapper with imperfect support, I would just 
disable REQ_OP_ZONE_APPEND on device mapper at all.

Mikulas




[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [SCSI Target Devel]     [Linux SCSI Target Infrastructure]     [Kernel Newbies]     [IDE]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux ATA RAID]     [Linux IIO]     [Samba]     [Device Mapper]

  Powered by Linux