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854f8871ed
If a file has FI_COMPRESS_RELEASED, all writes for it should not be
allowed. However, as of now, in case of compress_mode=user, writes
triggered by IOCTLs like F2FS_IOC_DE/COMPRESS_FILE are allowed unexpectly,
which could crash that file.
To fix it, let's do not allow F2FS_IOC_DE/COMPRESS_IOCTL if a file already
has FI_COMPRESS_RELEASED flag.
This is the reproduction process:
1. $ touch ./file
2. $ chattr +c ./file
3. $ dd if=/dev/random of=./file bs=4096 count=30 conv=notrunc
4. $ dd if=/dev/zero of=./file bs=4096 count=34 seek=30 conv=notrunc
5. $ sync
6. $ do_compress ./file ; call F2FS_IOC_COMPRESS_FILE
7. $ get_compr_blocks ./file ; call F2FS_IOC_GET_COMPRESS_BLOCKS
8. $ release ./file ; call F2FS_IOC_RELEASE_COMPRESS_BLOCKS
9. $ do_compress ./file ; call F2FS_IOC_COMPRESS_FILE again
10. $ get_compr_blocks ./file ; call F2FS_IOC_GET_COMPRESS_BLOCKS again
This reproduction process is tested in 128kb cluster size.
You can find compr_blocks has a negative value.
Fixes: 5fdb322ff2 ("f2fs: add F2FS_IOC_DECOMPRESS_FILE and F2FS_IOC_COMPRESS_FILE")
Signed-off-by: Junbeom Yeom <junbeom.yeom@samsung.com>
Signed-off-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Youngjin Gil <youngjin.gil@samsung.com>
Signed-off-by: Jaewook Kim <jw5454.kim@samsung.com>
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.