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[ Upstream commit f06c0f82e38bbda7264d6ef3c90045ad2810e0f3 ] Commit59c9081bc8("f2fs: allow write page cache when writting cp") allows write() to write data to page cache during checkpoint, so block count fields like .total_valid_block_count, .alloc_valid_block_count and .rf_node_block_count may encounter race condition as below: CP Thread A - write_checkpoint - block_operations - f2fs_down_write(&sbi->node_change) - __prepare_cp_block : ckpt->valid_block_count = .total_valid_block_count - f2fs_up_write(&sbi->node_change) - write - f2fs_preallocate_blocks - f2fs_map_blocks(,F2FS_GET_BLOCK_PRE_AIO) - f2fs_map_lock - f2fs_down_read(&sbi->node_change) - f2fs_reserve_new_blocks - inc_valid_block_count : percpu_counter_add(&sbi->alloc_valid_block_count, count) : sbi->total_valid_block_count += count - f2fs_up_read(&sbi->node_change) - do_checkpoint : sbi->last_valid_block_count = sbi->total_valid_block_count : percpu_counter_set(&sbi->alloc_valid_block_count, 0) : percpu_counter_set(&sbi->rf_node_block_count, 0) - fsync - need_do_checkpoint - f2fs_space_for_roll_forward : alloc_valid_block_count was reset to zero, so, it may missed last data during checkpoint Let's change to update .total_valid_block_count, .alloc_valid_block_count and .rf_node_block_count in block_operations(), then their access can be protected by .node_change and .cp_rwsem lock, so that it can avoid above race condition. Fixes:59c9081bc8("f2fs: allow write page cache when writting cp") Cc: Yunlei He <heyunlei@oppo.com> Signed-off-by: Chao Yu <chao@kernel.org> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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.