linux-stable.git/drivers/block/zram, branch v5.8

Revert "zram: convert remaining CLASS_ATTR() to CLASS_ATTR_RO()"

2020-07-01T15:29:05+00:00

Turns out that the permissions for 0400 really are what we want here,
otherwise any user can read from this file.

[fixed formatting, added changelog, and made attribute static - gregkh]

Reported-by: Wade Mealing 
Cc: stable 
Fixes: f40609d1591f ("zram: convert remaining CLASS_ATTR() to CLASS_ATTR_RO()")
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1847832
Reviewed-by: Steffen Maier 
Acked-by: Minchan Kim 
Link: https://lore.kernel.org/r/20200617114946.GA2131650@kroah.com
Signed-off-by: Greg Kroah-Hartman

zcomp: Use ARRAY_SIZE() for backends list

2020-06-05T02:06:24+00:00

Instead of keeping NULL terminated array switch to use ARRAY_SIZE()
which helps to further clean up.

Signed-off-by: Andy Shevchenko 
Signed-off-by: Andrew Morton 
Reviewed-by: Andrew Morton 
Acked-by: Minchan Kim 
Cc: Sergey Senozhatsky 
Cc: Jens Axboe 
Cc: Andy Shevchenko 
Link: http://lkml.kernel.org/r/20200508100758.51644-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Linus Torvalds

Merge tag 'for-5.8/block-2020-06-01' of git://git.kernel.dk/linux-block

2020-06-02T22:29:19+00:00

Pull block updates from Jens Axboe:
 "Core block changes that have been queued up for this release:

   - Remove dead blk-throttle and blk-wbt code (Guoqing)

   - Include pid in blktrace note traces (Jan)

   - Don't spew I/O errors on wouldblock termination (me)

   - Zone append addition (Johannes, Keith, Damien)

   - IO accounting improvements (Konstantin, Christoph)

   - blk-mq hardware map update improvements (Ming)

   - Scheduler dispatch improvement (Salman)

   - Inline block encryption support (Satya)

   - Request map fixes and improvements (Weiping)

   - blk-iocost tweaks (Tejun)

   - Fix for timeout failing with error injection (Keith)

   - Queue re-run fixes (Douglas)

   - CPU hotplug improvements (Christoph)

   - Queue entry/exit improvements (Christoph)

   - Move DMA drain handling to the few drivers that use it (Christoph)

   - Partition handling cleanups (Christoph)"

* tag 'for-5.8/block-2020-06-01' of git://git.kernel.dk/linux-block: (127 commits)
  block: mark bio_wouldblock_error() bio with BIO_QUIET
  blk-wbt: rename __wbt_update_limits to wbt_update_limits
  blk-wbt: remove wbt_update_limits
  blk-throttle: remove tg_drain_bios
  blk-throttle: remove blk_throtl_drain
  null_blk: force complete for timeout request
  blk-mq: drain I/O when all CPUs in a hctx are offline
  blk-mq: add blk_mq_all_tag_iter
  blk-mq: open code __blk_mq_alloc_request in blk_mq_alloc_request_hctx
  blk-mq: use BLK_MQ_NO_TAG in more places
  blk-mq: rename BLK_MQ_TAG_FAIL to BLK_MQ_NO_TAG
  blk-mq: move more request initialization to blk_mq_rq_ctx_init
  blk-mq: simplify the blk_mq_get_request calling convention
  blk-mq: remove the bio argument to ->prepare_request
  nvme: force complete cancelled requests
  blk-mq: blk-mq: provide forced completion method
  block: fix a warning when blkdev.h is included for !CONFIG_BLOCK builds
  block: blk-crypto-fallback: remove redundant initialization of variable err
  block: reduce part_stat_lock() scope
  block: use __this_cpu_add() instead of access by smp_processor_id()
  ...

zram: Use local lock to protect per-CPU data

2020-05-28T08:31:10+00:00

The zcomp driver uses per-CPU compression. The per-CPU data pointer is
acquired with get_cpu_ptr() which implicitly disables preemption.
It allocates memory inside the preempt disabled region which conflicts
with the PREEMPT_RT semantics.

Replace the implicit preemption control with an explicit local lock.
This allows RT kernels to substitute it with a real per CPU lock, which
serializes the access but keeps the code section preemptible. On non RT
kernels this maps to preempt_disable() as before, i.e. no functional
change.

[bigeasy: Use local_lock(), description, drop reordering]

Signed-off-by: Mike Galbraith 
Signed-off-by: Sebastian Andrzej Siewior 
Signed-off-by: Ingo Molnar 
Acked-by: Peter Zijlstra 
Link: https://lore.kernel.org/r/20200527201119.1692513-8-bigeasy@linutronix.de

zram: Allocate struct zcomp_strm as per-CPU memory

2020-05-28T08:31:10+00:00

zcomp::stream is a per-CPU pointer, pointing to struct zcomp_strm
which contains two pointers. Having struct zcomp_strm allocated
directly as per-CPU memory would avoid one additional memory
allocation and a pointer dereference. This also simplifies the
addition of a local_lock to struct zcomp_strm.

Allocate zcomp::stream directly as per-CPU memory.

Signed-off-by: Sebastian Andrzej Siewior 
Signed-off-by: Ingo Molnar 
Acked-by: Peter Zijlstra 
Link: https://lore.kernel.org/r/20200527201119.1692513-7-bigeasy@linutronix.de

zram: nvdimm: use bio_{start,end}_io_acct and disk_{start,end}_io_acct

2020-05-27T11:21:23+00:00

Switch zram to use the nicer bio accounting helpers, and as part of that
ensure each bio is counted as a single I/O request.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Konstantin Khlebnikov 
Signed-off-by: Jens Axboe

block: simplify queue allocation

2020-03-27T16:23:43+00:00

Current make_request based drivers use either blk_alloc_queue_node or
blk_alloc_queue to allocate a queue, and then set up the make_request_fn
function pointer and a few parameters using the blk_queue_make_request
helper.  Simplify this by passing the make_request pointer to
blk_alloc_queue, and while at it merge the _node variant into the main
helper by always passing a node_id, and remove the superfluous gfp_mask
parameter.  A lower-level __blk_alloc_queue is kept for the blk-mq case.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

block: move the part_stat* helpers from genhd.h to a new header

2020-03-25T15:50:09+00:00

These macros are just used by a few files.  Move them out of genhd.h,
which is included everywhere into a new standalone header.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

drivers/block/zram/zram_drv.c: fix error return codes not being returned in writeback_store

2020-01-31T18:30:39+00:00

Currently when an error code -EIO or -ENOSPC in the for-loop of
writeback_store the error code is being overwritten by a ret = len
assignment at the end of the function and the error codes are being
lost.  Fix this by assigning ret = len at the start of the function and
remove the assignment from the end, hence allowing ret to be preserved
when error codes are assigned to it.

Addresses Coverity ("Unused value")

Link: http://lkml.kernel.org/r/20191128122958.178290-1-colin.king@canonical.com
Fixes: a939888ec38b ("zram: support idle/huge page writeback")
Signed-off-by: Colin Ian King 
Acked-by: Minchan Kim 
Cc: Sergey Senozhatsky 
Cc: Jens Axboe 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

zram: try to avoid worst-case scenario on same element pages

2020-01-31T18:30:39+00:00

The worst-case scenario on finding same element pages is that almost all
elements are same at the first glance but only last few elements are
different.

Since the same element tends to be grouped from the beginning of the
pages, if we check the first element with the last element before
looping through all elements, we might have some chances to quickly
detect non-same element pages.

 1. Test is done under LG webOS TV (64-bit arch)
 2. Dump the swap-out pages (~819200 pages)
 3. Analyze the pages with simple test script which counts the iteration
    number and measures the speed at off-line

Under 64-bit arch, the worst iteration count is PAGE_SIZE / 8 bytes =
512.  The speed is based on the time to consume page_same_filled()
function only.  The result, on average, is listed as below:

                                     Num of Iter    Speed(MB/s)
  Looping-Forward (Orig)                 38            99265
  Looping-Backward                       36           102725
  Last-element-check (This Patch)        33           125072

The result shows that the average iteration count decreases by 13% and
the speed increases by 25% with this patch.  This patch does not
increase the overall time complexity, though.

I also ran simpler version which uses backward loop.  Just looping
backward also makes some improvement, but less than this patch.

[taejoon.song@lge.com: fix off-by-one]
  Link: http://lkml.kernel.org/r/1578642001-11765-1-git-send-email-taejoon.song@lge.com
Link: http://lkml.kernel.org/r/1575424418-16119-1-git-send-email-taejoon.song@lge.com
Signed-off-by: Taejoon Song 
Acked-by: Minchan Kim 
Cc: Sergey Senozhatsky 
Cc: Jens Axboe 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds