The typedefs are just annoying. 'mdk' probably refers to 'md_k.h'
which used to be an include file that defined this thing.
Signed-off-by: NNeilBrown <neilb@suse.de>

I don't know what I was thinking putting 'rcu' after a dynamically
sized array!  The array could still be in use when we call rcu_free()
(That is the point) so we mustn't corrupt it.

Cc: stable@kernel.org
Signed-off-by: NNeilBrown <neilb@suse.de>

Current, when we update the 'conf' structure, when adding a
drive to a linear array, we keep the old version around until
the array is finally stopped, as it is not safe to free it
immediately.

Now that we have rcu protection on all accesses to 'conf',
we can use call_rcu to free it more promptly.
Signed-off-by: NNeilBrown <neilb@suse.de>

Remove num_sectors from dev_info and replace start_sector with
end_sector.  This makes a lot of comparisons much simpler.
Signed-off-by: NSandeep K Sinha <sandeepksinha@gmail.com>
Signed-off-by: NNeilBrown <neilb@suse.de>

Get rid of sector_div and hash table for linear raid and replace
with a linear search in which_dev.
The hash table adds a lot of complexity for little if any gain.
Ultimately a binary search will be used which will have smaller
cache foot print, a similar number of memory access, and no
divisions.
Signed-off-by: NSandeep K Sinha <sandeepksinha@gmail.com>
Signed-off-by: NNeilBrown <neilb@suse.de>

Having a macro just to cast a void* isn't really helpful.
I would must rather see that we are simply de-referencing ->private,
than have to know what the macro does.

So open code the macro everywhere and remove the pointless cast.
Signed-off-by: NNeilBrown <neilb@suse.de>

This makes the includes more explicit, and is preparation for moving
md_k.h to drivers/md/md.h

Remove include/raid/md.h as its only remaining use was to #include
other files.
Signed-off-by: NNeilBrown <neilb@suse.de>

Move the headers with the local structures for the disciplines and
bitmap.h into drivers/md/ so that they are more easily grepable for
hacking and not far away.  md.h is left where it is for now as there
are some uses from the outside.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NNeilBrown <neilb@suse.de>

This patch renames hash_spacing and preshift to  spacing and
sector_shift respectively with the following change of semantics:

Case 1: (sizeof(sector_t) <= sizeof(u32)).
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In this case, we have sector_shift = preshift = 0 and spacing =
2 * hash_spacing.

Hence, the index for the hash table which is computed by the new code
in which_dev() as sector / spacing equals the old value which was
(sector/2) / hash_spacing.

Note also that the value of nb_zone stays the same because both sz
and base double.

Case 2: (sizeof(sector_t) > sizeof(u32)).
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

(aka the shifting dance case). Here we have sector_shift = preshift +
1 and

spacing = 2 * hash_spacing

during the computation of nb_zone and curr_sector, but

spacing = hash_spacing

in which_dev() because in the last hunk of the patch for linear.c we
shift down conf->spacing (= 2 * hash_spacing) by one more bit than
in the old code.

Hence in the computation of nb_zone, sz and base have the same value
as before, so nb_zone is not affected. Also curr_sector in the next
hunk stays the same.

In which_dev() the hash table index is computed as

(sector >> sector_shift) / spacing

In view of sector_shift = preshift + 1 and spacing = hash_spacing,
this equals

((sector/2) >> preshift) / hash_spacing

which is the value computed by the old code.
Signed-off-by: NAndre Noll <maan@systemlinux.org>
Signed-off-by: NNeilBrown <neilb@suse.de>

Rename them to num_sectors and start_sector which is more descriptive.
Signed-off-by: NAndre Noll <maan@systemlinux.org>
Signed-off-by: NNeilBrown <neilb@suse.de>

Signed-off-by: NAndre Noll <maan@systemlinux.org>
Signed-off-by: NNeilBrown <neilb@suse.de>

Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

linear currently uses division by the size of the smallest componenet device
to find which device a request goes to.  If that smallest device is larger
than 2 terabytes, then the division will not work on some systems.

So we introduce a pre-shift, and take care not to make the hash table too
large, much like the code in raid0.

Also get rid of conf->nr_zones, which is not needed.
Signed-off-by: NNeil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!