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Filename Latest commit message Latest commit date
Coly Li 6147305c73 bcache: set CACHE_SET_IO_DISABLE in bch_cached_dev_error()
Commit c7b7bd0740 ("bcache: add io_disable to struct cached_dev") tries
to stop bcache device by calling bcache_device_stop() when too many I/O
errors happened on backing device. But if there is internal I/O happening
on cache device (writeback scan, garbage collection, etc), a regular I/O
request triggers the internal I/Os may still holds a refcount of dc->count,
and the refcount may only be dropped after the internal I/O stopped.

By this patch, bch_cached_dev_error() will check if the backing device is
attached to a cache set, if yes that CACHE_SET_IO_DISABLE will be set to
flags of this cache set. Then internal I/Os on cache device will be
rejected and stopped immediately, and the bcache device can be stopped.

For people who are not familiar with the interesting refcount dependance,
let me explain a bit more how the fix works. Example the writeback thread
will scan cache device for dirty data writeback purpose. Before it stopps,
it holds a refcount of dc->count. When CACHE_SET_IO_DISABLE bit is set,
the internal I/O will stopped and the while-loop in bch_writeback_thread()
quits and calls cached_dev_put() to drop dc->count. If this is the last
refcount to drop, then cached_dev_detach_finish() will be called. In this
call back function, in turn closure_put(dc->disk.cl) is called to drop a
refcount of closure dc->disk.cl. If this is the last refcount of this
closure to drop, then cached_dev_flush() will be called. Then the cached
device is freed. So if CACHE_SET_IO_DISABLE is not set, the bache device
can not be stopped until all inernal cache device I/O stopped. For large
size cache device, and writeback thread competes locks with gc thread,
there might be a quite long time to wait.

Fixes: c7b7bd0740 ("bcache: add io_disable to struct cached_dev")
Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-03 08:35:10 -06:00
arch RISC-V: build vdso-dummy.o with -no-pie 2018-04-24 10:54:46 -07:00
block blk-mq: fix sysfs inflight counter 2018-04-26 09:02:01 -06:00
certs
crypto
Documentation Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/evalenti/linux-soc-thermal 2018-04-20 10:56:32 -07:00
drivers bcache: set CACHE_SET_IO_DISABLE in bch_cached_dev_error() 2018-05-03 08:35:10 -06:00
firmware
fs various SMB3/CIFS fixes for stable 4.17-rc1 2018-04-22 12:13:04 -07:00
include blk-mq: fix sysfs inflight counter 2018-04-26 09:02:01 -06:00
init
ipc
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-04-24 14:16:40 -07:00
lib dma-direct: don't retry allocation for no-op GFP_DMA 2018-04-23 14:43:27 +02:00
LICENSES
mm mm/filemap.c: fix NULL pointer in page_cache_tree_insert() 2018-04-20 17:18:36 -07:00
net packet: fix bitfield update race 2018-04-24 13:17:08 -04:00
samples
scripts
security Merge branch 'userns-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2018-04-24 17:58:51 -07:00
sound sound fixes for 4.17-rc2 2018-04-21 10:32:16 -07:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-04-24 14:16:40 -07:00
usr
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS for-linus-20180425 2018-04-25 21:05:15 -07:00
Makefile Linux 4.17-rc2 2018-04-22 19:20:09 -07:00
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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.