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When compressed file has blocks, f2fs_ioc_start_atomic_write will succeed, but compressed flag will be remained in inode. If write partial compreseed cluster and commit atomic write will cause data corruption. This is the reproduction process: Step 1: create a compressed file ,write 64K data , call fsync(), then the blocks are write as compressed cluster. Step2: iotcl(F2FS_IOC_START_ATOMIC_WRITE) --- this should be fail, but not. write page 0 and page 3. iotcl(F2FS_IOC_COMMIT_ATOMIC_WRITE) -- page 0 and 3 write as normal file, Step3: drop cache. read page 0-4 -- Since page 0 has a valid block address, read as non-compressed cluster, page 1 and 2 will be filled with compressed data or zero. The root cause is, after commit7eab7a6968("f2fs: compress: remove unneeded read when rewrite whole cluster"), in step 2, f2fs_write_begin() only set target page dirty, and in f2fs_commit_inmem_pages(), we will write partial raw pages into compressed cluster, result in corrupting compressed cluster layout. Fixes:4c8ff7095b("f2fs: support data compression") Fixes:7eab7a6968("f2fs: compress: remove unneeded read when rewrite whole cluster") Reported-by: kernel test robot <lkp@intel.com> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Fengnan Chang <changfengnan@vivo.com> Reviewed-by: Chao Yu <chao@kernel.org> Signed-off-by: Jaegeuk Kim <jaegeuk@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.