Re: Accessing odd last partition sector (was: [Linux-NTFS-Dev] mkntfs dirty volume marking)

[viro@parcelfarce.linux.theplanet.co.uk]

On Sat, Apr 10, 2004 at 11:04:45PM +0200, Szakacsits Szabolcs wrote:
> 
> On Sat, 10 Apr 2004 viro@parcelfarce.linux.theplanet.co.uk wrote:
> > On Sat, Apr 10, 2004 at 10:29:37PM +0200, Andries Brouwer wrote:
> > > On Fri, Apr 09, 2004 at 01:38:51PM +0200, Szakacsits Szabolcs wrote:
> > > 
> > > > > TODO.ntfsprogs conatins the following TODO item under mkntfs:
> > > > >  - We don't know what the real last sector is, thus we mark the volume
> > > > > dirty and the subsequent chkdsk (which will happen on reboot into
> > > > > Windows automatically) recreates the backup boot sector if the Linux
> > > > > kernel lied to us about the number of sectors.
> > > 
> > > The ioctl BLKGETSIZE64 will tell you the size (in bytes) of a block device.
> > 
> > So will lseek() to SEEK_END, actually (both 2.4 and 2.6).
> > And yes, last sector _is_ accessible for dd(1) et.al.
> 
> In 2.6? Not for 2.4 when I tried (it wasn't the latest 2.4 kernel).

2.4 logics around block size handling is broken; we probably could backport
that series of patches, though.  2.6 simply sets block size to GCD(page size,
device size), so we don't have to worry about all that crap.