o_direct-11 and blkdev-pagecache-8

[Andrea Arcangeli]

Here the latest release against 2.4.8pre3.

For the blkdev-pagecache I decreased performance going to 1k I/O
granularity to provide total backwards compatibility, otherwise it was
not possible to read the last bytes of the device if the size of the
device was not a multiple of 4k and there's no way to work around that
without intensive changes :(, this in turn means the doing O_DIRECT on
the blkdevice now has a constraint of 1k I/O granularity on the
read/write API (not anymore the more restrictive 4k granularity).

The O_DIRECT patch includes a one liner I got from the GFS folks to
update the i_size of the inode correctly.

They must be applyed in order:

	ftp://ftp.us.kernel.org/pub/linux/kernel/people/andrea/patches/v2.4/2.4.8pre3/o_direct-11
	ftp://ftp.us.kernel.org/pub/linux/kernel/people/andrea/patches/v2.4/2.4.8pre3/blkdev-pagecache-8

Now it would be nice to have a patch incremental to those so that rawio
also uses the preallocated per-file iobuf (note: the preallocation
should happen in the rawio layer, not in the vfs like we just do with
the generic O_DIRECT).

Andrea