litmus-rt.git/Documentation/blockdev, branch v2015.1

Merge branch 'for-4.1/drivers' of git://git.kernel.dk/linux-block

2015-04-17T02:05:27+00:00

Pull block driver updates from Jens Axboe:
 "This is the block driver pull request for 4.1.  As with the core bits,
  this is a relatively slow round.  This pull request contains:

   - Various fixes and cleanups for NVMe, from Alexey Khoroshilov, Chong
     Yuan, myself, Keith Busch, and Murali Iyer.

   - Documentation and code cleanups for nbd from Markus Pargmann.

   - Change of brd maintainer to me, from Ross Zwisler.  At least the
     email doesn't bounce anymore then.

   - Two xen-blkback fixes from Tao Chen"

* 'for-4.1/drivers' of git://git.kernel.dk/linux-block: (23 commits)
  NVMe: Meta data handling through submit io ioctl
  NVMe: Add translation for block limits
  NVMe: Remove check for null
  NVMe: Fix error handling of class_create("nvme")
  xen-blkback: define pr_fmt macro to avoid the duplication of DRV_PFX
  xen-blkback: enlarge the array size of blkback name
  nbd: Return error pointer directly
  nbd: Return error code directly
  nbd: Remove fixme that was already fixed
  nbd: Restructure debugging prints
  nbd: Fix device bytesize type
  nbd: Replace kthread_create with kthread_run
  nbd: Remove kernel internal header
  Documentation: nbd: Add list of module parameters
  Documentation: nbd: Reformat to allow more documentation
  NVMe: increase depth of admin queue
  nvme: Fix PRP list calculation for non-4k system page size
  NVMe: Fix blk-mq hot cpu notification
  NVMe: embedded iod mask cleanup
  NVMe: Freeze admin queue on device failure
  ...

zram: deprecate zram attrs sysfs nodes

2015-04-15T23:35:21+00:00

Add Documentation/ABI/obsolete/sysfs-block-zram file and list obsolete and
deprecated attributes there.  The patch also adds additional information
to zram documentation and describes the basic strategy:

- the existing RW nodes will be downgraded to WO nodes (in 4.11)
- deprecated RO sysfs nodes will eventually be removed (in 4.11)

Users will be additionally notified about deprecated attr usage by
pr_warn_once() (added to every deprecated attr _show()), as suggested by
Minchan Kim.

User space is advised to use zram/stat, zram/io_stat and
zram/mm_stat files.

Signed-off-by: Sergey Senozhatsky 
Reported-by: Minchan Kim 
Cc: Nitin Gupta 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

zram: export new 'mm_stat' sysfs attrs

2015-04-15T23:35:21+00:00

Per-device `zram/mm_stat' file provides mm statistics of a particular
zram device in a format similar to block layer statistics.  The file
consists of a single line and represents the following stats (separated by
whitespace):

        orig_data_size
        compr_data_size
        mem_used_total
        mem_limit
        mem_used_max
        zero_pages
        num_migrated

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

zram: export new 'io_stat' sysfs attrs

2015-04-15T23:35:21+00:00

Per-device `zram/io_stat' file provides accumulated I/O statistics of
particular zram device in a format similar to block layer statistics.  The
file consists of a single line and represents the following stats
(separated by whitespace):

        failed_reads
        failed_writes
        invalid_io
        notify_free

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

zram: describe device attrs in documentation

2015-04-15T23:35:21+00:00

Briefly describe exported device stat attrs in zram documentation.  We
will eventually get rid of per-stat sysfs nodes and, thus, clean up
Documentation/ABI/testing/sysfs-block-zram file, which is the only source
of information about device sysfs nodes.

Add `num_migrated' description, since there is no independent
`num_migrated' sysfs node (and no corresponding sysfs-block-zram entry),
it will be exported via zram/mm_stat file.

At this point we can provide minimal description, because sysfs-block-zram
still contains detailed information.

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

Documentation: nbd: Add list of module parameters

2015-04-02T18:39:15+00:00

Add a list of available module parameters as attachment to the
documentation.

Signed-off-by: Markus Pargmann 
Signed-off-by: Jens Axboe

Documentation: nbd: Reformat to allow more documentation

2015-04-02T18:39:13+00:00

Reformat the existing documentation to have more structure. This allows
for more documentation seperated from the existing paragraphs.

Signed-off-by: Markus Pargmann 
Signed-off-by: Jens Axboe

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

zram: zram memory size limitation

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

Since zram has no control feature to limit memory usage, it makes hard to
manage system memrory.

This patch adds new knob "mem_limit" via sysfs to set up the a limit so
that zram could fail allocation once it reaches the limit.

In addition, user could change the limit in runtime so that he could
manage the memory more dynamically.

Initial state is no limit so it doesn't break old behavior.

[akpm@linux-foundation.org: fix typo, per Sergey]
Signed-off-by: Minchan Kim 
Cc: Dan Streetman 
Cc: Sergey Senozhatsky 
Cc: Jerome Marchand 
Cc: 
Cc: 
Cc: Luigi Semenzato 
Cc: Nitin Gupta 
Cc: Seth Jennings 
Cc: David Horner 
Cc: Joonsoo Kim 
Cc: Minchan Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

zram: propagate error to user

2014-04-07T23:36:02+00:00

When we initialized zcomp with single, we couldn't change
max_comp_streams without zram reset but current interface doesn't show
any error to user and even it changes max_comp_streams's value without
any effect so it would make user very confusing.

This patch prevents max_comp_streams's change when zcomp was initialized
as single zcomp and emit the error to user(ex, echo).

[akpm@linux-foundation.org: don't return with the lock held, per Sergey]
[fengguang.wu@intel.com: fix coccinelle warnings]
Signed-off-by: Minchan Kim 
Cc: Nitin Gupta 
Cc: Jerome Marchand 
Acked-by: Sergey Senozhatsky 
Signed-off-by: Fengguang Wu 
Cc: Stephen Rothwell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds