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Filename Latest commit message Latest commit date
Shenghui Wang 79b791466e bcache: do not mark writeback_running too early
A fresh backing device is not attached to any cache_set, and
has no writeback kthread created until first attached to some
cache_set.

But bch_cached_dev_writeback_init run
"
	dc->writeback_running		= true;
	WARN_ON(test_and_clear_bit(BCACHE_DEV_WB_RUNNING,
			&dc->disk.flags));
"
for any newly formatted backing devices.

For a fresh standalone backing device, we can get something like
following even if no writeback kthread created:
------------------------
/sys/block/bcache0/bcache# cat writeback_running
1
/sys/block/bcache0/bcache# cat writeback_rate_debug
rate:		512.0k/sec
dirty:		0.0k
target:		0.0k
proportional:	0.0k
integral:	0.0k
change:		0.0k/sec
next io:	-15427384ms

The none ZERO fields are misleading as no alive writeback kthread yet.

Set dc->writeback_running false as no writeback thread created in
bch_cached_dev_writeback_init().

We have writeback thread created and woken up in bch_cached_dev_writeback
_start(). Set dc->writeback_running true before bch_writeback_queue()
called, as a writeback thread will check if dc->writeback_running is true
before writing back dirty data, and hung if false detected.

After the change, we can get the following output for a fresh standalone
backing device:
-----------------------
/sys/block/bcache0/bcache$ cat writeback_running
0
/sys/block/bcache0/bcache# cat writeback_rate_debug
rate:		0.0k/sec
dirty:		0.0k
target:		0.0k
proportional:	0.0k
integral:	0.0k
change:		0.0k/sec
next io:	0ms

v1 -> v2:
  Set dc->writeback_running before bch_writeback_queue() called,

Signed-off-by: Shenghui Wang <shhuiw@foxmail.com>
Signed-off-by: Coly Li <colyli@suse.de>

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-13 08:15:54 -07:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-12-09 15:12:33 -08:00
block blkcg: handle dying request_queue when associating a blkg 2018-12-12 17:43:33 -07:00
certs
crypto
Documentation Linux 4.20-rc6 2018-12-09 17:45:40 -07:00
drivers bcache: do not mark writeback_running too early 2018-12-13 08:15:54 -07:00
firmware
fs Linux 4.20-rc6 2018-12-09 17:45:40 -07:00
include blkcg: handle dying request_queue when associating a blkg 2018-12-12 17:43:33 -07:00
init
ipc
kernel Linux 4.20-rc6 2018-12-09 17:45:40 -07:00
lib sbitmap: flush deferred clears for resize and shallow gets 2018-12-11 18:39:41 -07:00
LICENSES
mm Linux 4.20-rc6 2018-12-09 17:45:40 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-12-09 15:12:33 -08:00
samples
scripts
security
sound
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-12-09 15:12:33 -08:00
usr
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-12-09 15:12:33 -08:00
Makefile Linux 4.20-rc6 2018-12-09 15:31:00 -08:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.