Sheng Yong 58282978fe f2fs: fix race between write_checkpoint and write_begin
[ Upstream commit 2866fb16d6 ]

The following race could lead to inconsistent SIT bitmap:

Task A                          Task B
======                          ======
f2fs_write_checkpoint
  block_operations
    f2fs_lock_all
      down_write(node_change)
      down_write(node_write)
      ... sync ...
      up_write(node_change)
                                f2fs_file_write_iter
                                  set_inode_flag(FI_NO_PREALLOC)
                                  ......
                                  f2fs_write_begin(index=0, has inline data)
                                    prepare_write_begin
                                      __do_map_lock(AIO) => down_read(node_change)
                                      f2fs_convert_inline_page => update SIT
                                      __do_map_lock(AIO) => up_read(node_change)
  f2fs_flush_sit_entries <= inconsistent SIT
  finish write checkpoint
  sudden-power-off

If SPO occurs after checkpoint is finished, SIT bitmap will be set
incorrectly.

Signed-off-by: Sheng Yong <shengyong1@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-02-12 19:46:00 +01:00
2019-02-06 17:31:37 +01:00

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

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.
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