linux-stable.git/drivers/block/zram, branch linux-3.19.y

zram: use DEVICE_ATTR_[RW|RO|WO] to define zram sys device attribute

2014-12-13T20:42:50+00:00

In current zram, we use DEVICE_ATTR() to define sys device attributes.
SO, we need to set (S_IRUGO | S_IWUSR) permission and other arguments
manually.  Linux already provids the macro DEVICE_ATTR_[RW|RO|WO] to
define sys device attribute.  It is simple and readable.

This patch uses kernel defined macro DEVICE_ATTR_[RW|RO|WO] to define
zram device attribute.

Signed-off-by: Ganesh Mahendran 
Acked-by: Jerome Marchand 
Cc: Minchan Kim 
Cc: Nitin Gupta 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/zram: correct ZRAM_ZERO flag bit position

2014-12-13T20:42:50+00:00

In struct zram_table_entry, the element *value* contains obj size and obj
zram flags.  Bit 0 to bit (ZRAM_FLAG_SHIFT - 1) represent obj size, and
bit ZRAM_FLAG_SHIFT to the highest bit of unsigned long represent obj
zram_flags.  So the first zram flag(ZRAM_ZERO) should be from
ZRAM_FLAG_SHIFT instead of (ZRAM_FLAG_SHIFT + 1).

This patch fixes this cosmetic issue.

Also fix a typo, "page in now accessed" -> "page is now accessed"

Signed-off-by: Mahendran Ganesh 
Acked-by: Minchan Kim 
Acked-by: Weijie Yang 
Acked-by: Sergey Senozhatsky 
Cc: Nitin Gupta 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

zram: implement rw_page operation of zram

2014-12-13T20:42:50+00:00

This patch implements rw_page operation for zram block device.

I implemented the feature in zram and tested it.  Test bed was the G2, LG
electronic mobile device, whtich has msm8974 processor and 2GB memory.

With a memory allocation test program consuming memory, the system
generates swap.

Operating time of swap_write_page() was measured.

--------------------------------------------------
|             |   operating time   | improvement |
|             |  (20 runs average) |             |
--------------------------------------------------
|with patch   |    1061.15 us      |    +2.4%    |
--------------------------------------------------
|without patch|    1087.35 us      |             |
--------------------------------------------------

Each test(with paged_io,with BIO) result set shows normal distribution and
has equal variance.  I mean the two values are valid result to compare.  I
can say operation with paged I/O(without BIO) is faster 2.4% with
confidence level 95%.

[minchan@kernel.org: make rw_page opeartion return 0]
[minchan@kernel.org: rely on the bi_end_io for zram_rw_page fails]
[sergey.senozhatsky@gmail.com: code cleanup]
[minchan@kernel.org: add comment]
Signed-off-by: karam.lee 
Acked-by: Minchan Kim 
Acked-by: Jerome Marchand 
Cc: Matthew Wilcox 
Cc: Nitin Gupta 
Cc: 
Signed-off-by: Minchan Kim 
Signed-off-by: Sergey Senozhatsky 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

zram: change parameter from vaild_io_request()

2014-12-13T20:42:50+00:00

This patch changes parameter of valid_io_request for common usage.  The
purpose of valid_io_request() is to determine if bio request is valid or
not.

This patch use I/O start address and size instead of a BIO parameter for
common usage.

Signed-off-by: karam.lee 
Acked-by: Minchan Kim 
Acked-by: Jerome Marchand 
Cc: Matthew Wilcox 
Cc: Nitin Gupta 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

zram: remove bio parameter from zram_bvec_rw()

2014-12-13T20:42:49+00:00

Recently rw_page block device operation has been added.  This patchset
implements rw_page operation for zram block device and does some clean-up.

This patch (of 3):

Remove an unnecessary parameter(bio) from zram_bvec_rw() and
zram_bvec_read().  zram_bvec_read() doesn't use a bio parameter, so remove
it.  zram_bvec_rw() calls a read/write operation not using bio, so a rw
parameter replaces a bio parameter.

Signed-off-by: karam.lee 
Acked-by: Minchan Kim 
Acked-by: Jerome Marchand 
Cc: Matthew Wilcox 
Cc: Nitin Gupta 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

zram: avoid kunmap_atomic() of a NULL pointer

2014-11-14T00:17:05+00:00

zram could kunmap_atomic() a NULL pointer in a rare situation: a zram
page becomes a full-zeroed page after a partial write io.  The current
code doesn't handle this case and performs kunmap_atomic() on a NULL
pointer, which panics the kernel.

This patch fixes this issue.

Signed-off-by: Weijie Yang 
Cc: Sergey Senozhatsky 
Cc: Dan Streetman 
Cc: Nitin Gupta 
Cc: Weijie Yang 
Acked-by: Jerome Marchand 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

zram: avoid NULL pointer access in concurrent situation

2014-10-29T23:33:15+00:00

There is a rare NULL pointer bug in mem_used_total_show() and
mem_used_max_store() in concurrent situation, like this:

zram is not initialized, process A is a mem_used_total reader which runs
periodically, while process B try to init zram.

	process A 				process B
  access meta, get a NULL value
						init zram, done
  init_done() is true
  access meta->mem_pool, get a NULL pointer BUG

This patch fixes this issue.

Signed-off-by: Weijie Yang 
Acked-by: Minchan Kim 
Acked-by: Sergey Senozhatsky 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'for-3.18/drivers' of git://git.kernel.dk/linux-block

2014-10-18T19:12:45+00:00

Pull block layer driver update from Jens Axboe:
 "This is the block driver pull request for 3.18.  Not a lot in there
  this round, and nothing earth shattering.

   - A round of drbd fixes from the linbit team, and an improvement in
     asender performance.

   - Removal of deprecated (and unused) IRQF_DISABLED flag in rsxx and
     hd from Michael Opdenacker.

   - Disable entropy collection from flash devices by default, from Mike
     Snitzer.

   - A small collection of xen blkfront/back fixes from Roger Pau Monné
     and Vitaly Kuznetsov"

* 'for-3.18/drivers' of git://git.kernel.dk/linux-block:
  block: disable entropy contributions for nonrot devices
  xen, blkfront: factor out flush-related checks from do_blkif_request()
  xen-blkback: fix leak on grant map error path
  xen/blkback: unmap all persistent grants when frontend gets disconnected
  rsxx: Remove deprecated IRQF_DISABLED
  block: hd: remove deprecated IRQF_DISABLED
  drbd: use RB_DECLARE_CALLBACKS() to define augment callbacks
  drbd: compute the end before rb_insert_augmented()
  drbd: Add missing newline in resync progress display in /proc/drbd
  drbd: reduce lock contention in drbd_worker
  drbd: Improve asender performance
  drbd: Get rid of the WORK_PENDING macro
  drbd: Get rid of the __no_warn and __cond_lock macros
  drbd: Avoid inconsistent locking warning
  drbd: Remove superfluous newline from "resync_extents" debugfs entry.
  drbd: Use consistent names for all the bi_end_io callbacks
  drbd: Use better variable names

zram: use notify_free to account all free notifications

2014-10-10T02:26:03+00:00

`notify_free' device attribute accounts the number of slot free
notifications and internally represents the number of zram_free_page()
calls.  Slot free notifications are sent only when device is used as a
swap device, hence `notify_free' is used only for swap devices.  Since
f4659d8e620d08 (zram: support REQ_DISCARD) ZRAM handles yet another one
free notification (also via zram_free_page() call) -- REQ_DISCARD
requests, which are sent by a filesystem, whenever some data blocks are
discarded.  However, there is no way to know the number of notifications
in the latter case.

Use `notify_free' to account the number of pages freed by
zram_bio_discard() and zram_slot_free_notify().  Depending on usage
scenario `notify_free' represents:

 a) the number of pages freed because of slot free notifications, which is
   equal to the number of swap_slot_free_notify() calls, so there is no
   behaviour change

 b) the number of pages freed because of REQ_DISCARD notifications

Signed-off-by: Sergey Senozhatsky 
Acked-by: Minchan Kim 
Acked-by: Jerome Marchand 
Cc: Nitin Gupta 
Cc: Chao Yu 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

zram: report maximum used memory

2014-10-10T02:26:02+00:00

Normally, zram user could get maximum memory usage zram consumed via
polling mem_used_total with sysfs in userspace.

But it has a critical problem because user can miss peak memory usage
during update inverval of polling.  For avoiding that, user should poll it
with shorter interval(ie, 0.0000000001s) with mlocking to avoid page fault
delay when memory pressure is heavy.  It would be troublesome.

This patch adds new knob "mem_used_max" so user could see the maximum
memory usage easily via reading the knob and reset it via "echo 0 >
/sys/block/zram0/mem_used_max".

Signed-off-by: Minchan Kim 
Reviewed-by: Dan Streetman 
Cc: Sergey Senozhatsky 
Cc: Jerome Marchand 
Cc: 
Cc: 
Cc: Luigi Semenzato 
Cc: Nitin Gupta 
Cc: Seth Jennings 
Reviewed-by: David Horner 
Cc: Joonsoo Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds