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df4ad53242
There is a race condition in detaching as below:
A. detaching B. Write request
(1) writing back
(2) write back done, set bdev
state to clean.
(3) cached_dev_put() and
schedule_work(&dc->detach);
(4) write data [0 - 4K] directly
into backing and ack to user.
(5) power-failure...
When we restart this bcache device, this bdev is clean but not detached,
and read [0 - 4K], we will get unexpected old data from cache device.
To fix this problem, set the bdev state to none when we writeback done
in detaching, and then if power-failure happened as above, the data in
cache will not be used in next bcache device starting, it's detached, we
will read the correct data from backing derectly.
Signed-off-by: Dongsheng Yang <dongsheng.yang@easystack.cn>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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.