zs_get_total_size_bytes returns a amount of memory zsmalloc consumed with
*byte unit* but zsmalloc operates *page unit* rather than byte unit so
let's change the API so benefit we could get is that reduce unnecessary
overhead (ie, change page unit with byte unit) in zsmalloc.

Since return type is pages, "zs_get_total_pages" is better than
"zs_get_total_size_bytes".
Signed-off-by: NMinchan Kim <minchan@kernel.org>
Reviewed-by: NDan Streetman <ddstreet@ieee.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: <juno.choi@lge.com>
Cc: <seungho1.park@lge.com>
Cc: Luigi Semenzato <semenzato@google.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Seth Jennings <sjennings@variantweb.net>
Cc: David Horner <ds2horner@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add my copyright to the zsmalloc source code which I maintain.
Signed-off-by: NMinchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch moves zsmalloc under mm directory.

Before that, description will explain why we have needed custom
allocator.

Zsmalloc is a new slab-based memory allocator for storing compressed
pages.  It is designed for low fragmentation and high allocation success
rate on large object, but <= PAGE_SIZE allocations.

zsmalloc differs from the kernel slab allocator in two primary ways to
achieve these design goals.

zsmalloc never requires high order page allocations to back slabs, or
"size classes" in zsmalloc terms.  Instead it allows multiple
single-order pages to be stitched together into a "zspage" which backs
the slab.  This allows for higher allocation success rate under memory
pressure.

Also, zsmalloc allows objects to span page boundaries within the zspage.
This allows for lower fragmentation than could be had with the kernel
slab allocator for objects between PAGE_SIZE/2 and PAGE_SIZE.  With the
kernel slab allocator, if a page compresses to 60% of it original size,
the memory savings gained through compression is lost in fragmentation
because another object of the same size can't be stored in the leftover
space.

This ability to span pages results in zsmalloc allocations not being
directly addressable by the user.  The user is given an
non-dereferencable handle in response to an allocation request.  That
handle must be mapped, using zs_map_object(), which returns a pointer to
the mapped region that can be used.  The mapping is necessary since the
object data may reside in two different noncontigious pages.

The zsmalloc fulfills the allocation needs for zram perfectly

[sjenning@linux.vnet.ibm.com: borrow Seth's quote]
Signed-off-by: NMinchan Kim <minchan@kernel.org>
Acked-by: NNitin Gupta <ngupta@vflare.org>
Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Bob Liu <bob.liu@oracle.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Luigi Semenzato <semenzato@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch adds lots of comments and it will help others
to review and enhance.
Signed-off-by: NSeth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: NNitin Gupta <ngupta@vflare.org>
Signed-off-by: NMinchan Kim <minchan@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The existing comments are using an odd style. Fixed them up to adhere
to the StyleGuide. No code changes.
Signed-off-by: NSara Bird <sara.bird.iar@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

zs_create_pool() currently takes a name argument which is
never used in any useful way.

This patch removes it.
Signed-off-by: NSeth Jennings <sjenning@linux.vnet.ibm.com>
Acked-by: NNitin Gupta <ngupta@vflare.org>
Acked-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch improves mapping performance in zsmalloc by getting
usage information from the user in the form of a "mapping mode"
and using it to avoid unnecessary copying for objects that span
pages.
Signed-off-by: NSeth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

We should use unsigned long as handle instead of void * to avoid any
confusion. Without this, users may just treat zs_malloc return value as
a pointer and try to deference it.

This patch passed compile test(zram, zcache and ramster) and zram is
tested on qemu.

changelog
  * from v2
	- remove hval pointed out by Nitin
	- based on next-20120607
  * from v1
	- change zcache's zv_create return value
	- baesd on next-20120604

Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Acked-by: NSeth Jennings <sjenning@linux.vnet.ibm.com>
Acked-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NMinchan Kim <minchan@kernel.org>
Acked-by: NNitin Gupta <ngupta@vflare.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch creates a new memory allocation library named
zsmalloc.

NOTE: zsmalloc currently depends on SPARSEMEM for the MAX_PHYSMEM_BITS
value needed to determine the format of the object handle. There may
be a better way to do this.  Feedback is welcome.
Signed-off-by: NNitin Gupta <ngupta@vflare.org>
Signed-off-by: NSeth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>