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[ Upstream commite3b49ea368] Encrypted pages during GC are read and cached in META_MAPPING. However, due to cached pages in META_MAPPING, there is an issue where newly written pages are lost by IPU or DIO writes. Thread A - f2fs_gc() Thread B /* phase 3 */ down_write(i_gc_rwsem) ra_data_block() ---- (a) up_write(i_gc_rwsem) f2fs_direct_IO() : - down_read(i_gc_rwsem) - __blockdev_direct_io() - get_data_block_dio_write() - f2fs_dio_submit_bio() ---- (b) - up_read(i_gc_rwsem) /* phase 4 */ down_write(i_gc_rwsem) move_data_block() ---- (c) up_write(i_gc_rwsem) (a) In phase 3 of f2fs_gc(), up-to-date page is read from storage and cached in META_MAPPING. (b) In thread B, writing new data by IPU or DIO write on same blkaddr as read in (a). cached page in META_MAPPING become out-dated. (c) In phase 4 of f2fs_gc(), out-dated page in META_MAPPING is copied to new blkaddr. In conclusion, the newly written data in (b) is lost. To address this issue, invalidating pages in META_MAPPING before IPU or DIO write. Fixes:6aa58d8ad2("f2fs: readahead encrypted block during GC") Signed-off-by: Hyeong-Jun Kim <hj514.kim@samsung.com> Reviewed-by: Chao Yu <chao@kernel.org> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> Stable-dep-of: fd244524c2cf ("f2fs: compress: fix to cover normal cluster write with cp_rwsem") 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.