linux-stable.git/drivers/block/loop.c, branch v4.0.4

block: destroy bdi before blockdev is unregistered.

2015-05-17T16:55:07+00:00

commit 6cd18e711dd8075da9d78cfc1239f912ff28968a upstream.

Because of the peculiar way that md devices are created (automatically
when the device node is opened), a new device can be created and
registered immediately after the
	blk_unregister_region(disk_devt(disk), disk->minors);
call in del_gendisk().

Therefore it is important that all visible artifacts of the previous
device are removed before this call.  In particular, the 'bdi'.

Since:
commit c4db59d31e39ea067c32163ac961e9c80198fd37
Author: Christoph Hellwig 
    fs: don't reassign dirty inodes to default_backing_dev_info

moved the
   device_unregister(bdi->dev);
call from bdi_unregister() to bdi_destroy() it has been quite easy to
lose a race and have a new (e.g.) "md127" be created after the
blk_unregister_region() call and before bdi_destroy() is ultimately
called by the final 'put_disk', which must come after del_gendisk().

The new device finds that the bdi name is already registered in sysfs
and complains

> [ 9627.630029] WARNING: CPU: 18 PID: 3330 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x5a/0x70()
> [ 9627.630032] sysfs: cannot create duplicate filename '/devices/virtual/bdi/9:127'

We can fix this by moving the bdi_destroy() call out of
blk_release_queue() (which can happen very late when a refcount
reaches zero) and into blk_cleanup_queue() - which happens exactly when the md
device driver calls it.

Then it is only necessary for md to call blk_cleanup_queue() before
del_gendisk().  As loop.c devices are also created on demand by
opening the device node, we make the same change there.

Fixes: c4db59d31e39ea067c32163ac961e9c80198fd37
Reported-by: Azat Khuzhin 
Cc: Christoph Hellwig 
Signed-off-by: NeilBrown 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

loop: add blk-mq.h include

2015-01-02T22:20:25+00:00

Looks like we pull it in through other ways on x86, but we fail
on sparc:

In file included from drivers/block/cryptoloop.c:30:0:
drivers/block/loop.h:63:24: error: field 'tag_set' has incomplete type
struct blk_mq_tag_set tag_set;

Add the include to loop.h, kill it from loop.c.

Signed-off-by: Jens Axboe

block: loop: don't handle REQ_FUA explicitly

2015-01-02T22:07:49+00:00

block core handles REQ_FUA by its flush state machine, so
won't do it in loop explicitly.

Signed-off-by: Ming Lei 
Signed-off-by: Jens Axboe

block: loop: introduce lo_discard() and lo_req_flush()

2015-01-02T22:07:49+00:00

No behaviour change, just move the handling for REQ_DISCARD
and REQ_FLUSH in these two functions.

Signed-off-by: Ming Lei 
Signed-off-by: Jens Axboe

block: loop: say goodby to bio

2015-01-02T22:07:49+00:00

Switch to block request completely.

Signed-off-by: Ming Lei 
Signed-off-by: Jens Axboe

block: loop: improve performance via blk-mq

2015-01-02T22:07:49+00:00

The conversion is a bit straightforward, and use work queue to
dispatch requests of loop block, and one big change is that requests
is submitted to backend file/device concurrently with work queue,
so throughput may get improved much. Given write requests over same
file are often run exclusively, so don't handle them concurrently for
avoiding extra context switch cost, possible lock contention and work
schedule cost. Also with blk-mq, there is opportunity to get loop I/O
merged before submitting to backend file/device.

In the following test:
	- base: v3.19-rc2-2041231
	- loop over file in ext4 file system on SSD disk
	- bs: 4k, libaio, io depth: 64, O_DIRECT, num of jobs: 1
	- throughput: IOPS

	------------------------------------------------------
	|            | base      | base with loop-mq | delta |
	------------------------------------------------------
	| randread   | 1740      | 25318             | +1355%|
	------------------------------------------------------
	| read       | 42196     | 51771             | +22.6%|
	-----------------------------------------------------
	| randwrite  | 35709     | 34624             | -3%   |
	-----------------------------------------------------
	| write      | 39137     | 40326             | +3%   |
	-----------------------------------------------------

So loop-mq can improve throughput for both read and randread, meantime,
performance of write and randwrite isn't hurted basically.

Another benefit is that loop driver code gets simplified
much after blk-mq conversion, and the patch can be thought as
cleanup too.

Signed-off-by: Ming Lei 
Signed-off-by: Jens Axboe

Merge branch 'sched/urgent' into sched/core, to avoid conflicts

2014-05-07T11:15:46+00:00

Signed-off-by: Ingo Molnar

sched, treewide: Replace hardcoded nice values with MIN_NICE/MAX_NICE

2014-04-18T10:07:24+00:00

Replace various -20/+19 hardcoded nice values with MIN_NICE/MAX_NICE.

Signed-off-by: Dongsheng Yang 
Acked-by: Tejun Heo 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/ff13819fd09b7a5dba5ab5ae797f2e7019bdfa17.1394532288.git.yangds.fnst@cn.fujitsu.com
Cc: devel@driverdev.osuosl.org
Cc: devicetree@vger.kernel.org
Cc: fcoe-devel@open-fcoe.org
Cc: linux390@de.ibm.com
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-s390@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Cc: nbd-general@lists.sourceforge.net
Cc: ocfs2-devel@oss.oracle.com
Cc: openipmi-developer@lists.sourceforge.net
Cc: qla2xxx-upstream@qlogic.com
Cc: linux-arch@vger.kernel.org
[ Consolidated the patches, twiddled the changelog. ]
Signed-off-by: Ingo Molnar

drivers/block/loop.c: ratelimit error messages

2014-04-08T20:44:35+00:00

Metric tons of high speed spew is not helpful when things go pear shaped.
systemd lost its mind, forgot how to stop services it insists on being
sole manager of, massive printk() flood ensued, box eventually died.

[16206.684000] loop: Write error at byte offset 11412291584, length 4096.
[16206.684000] systemd-journald[1758]: /dev/kmsg buffer overrun, some messages lost.
[16206.684000] loop: Write error at byte offset 13155434496, length 4096.
[16206.684000] loop: Write error at byte offset 13155438592, length 4096.
[16206.684000] loop: Write error at byte offset 13155442688, length 4096.
[16206.684000] loop: Write error at byte offset 13960736768, length 4096.
[16206.684000] loop: Write error at byte offset 14229172224, length 4096.
[16206.684000] systemd-journald[1758]: /dev/kmsg buffer overrun, some messages lost.
[16206.684000] loop: Write error at byte offset 14766043136, length 4096.
[16206.684000] loop: Write error at byte offset 15034478592, length 4096.
[16206.684000] systemd-journald[1758]: /dev/kmsg buffer overrun, some messages lost.

Signed-off-by: Mike Galbraith 
Cc: Jens Axboe 
Signed-off-by: Andrew Morton 
Signed-off-by: Jens Axboe

drivers/block/loop.c: fix comment typo in loop_config_discard

2014-01-22T04:16:56+00:00

Discard requests are ignored if the encryption is enabled for the given
loop device.  Update comment to match the code, and similar comments
elsewhere in the file.

Signed-off-by: Olaf Hering 
Signed-off-by: Andrew Morton 
Signed-off-by: Jens Axboe