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SubjectRe: [PATCH] docs: filesystems: f2fs: fix description about compress ioctl
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On 2022/6/2 15:25, Chao Liu wrote:
> From: Chao Liu <liuchao@coolpad.com>
>
> Since commit c61404153eb6 ("f2fs: introduce FI_COMPRESS_RELEASED
> instead of using IMMUTABLE bit"), we no longer use the IMMUTABLE
> bit to prevent writing data for compression. Let's correct the
> corresponding documentation.
>
> BTW, this patch fixes some alignment issues in the compress
> metadata layout.
>
> Signed-off-by: Chao Liu <liuchao@coolpad.com>
> ---
> Documentation/filesystems/f2fs.rst | 13 +++++++------
> 1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
> index ad8dc8c040a2..98dc24f5c6f0 100644
> --- a/Documentation/filesystems/f2fs.rst
> +++ b/Documentation/filesystems/f2fs.rst
> @@ -818,10 +818,11 @@ Compression implementation
> Instead, the main goal is to reduce data writes to flash disk as much as
> possible, resulting in extending disk life time as well as relaxing IO
> congestion. Alternatively, we've added ioctl(F2FS_IOC_RELEASE_COMPRESS_BLOCKS)
> - interface to reclaim compressed space and show it to user after putting the
> - immutable bit. Immutable bit, after release, it doesn't allow writing/mmaping
> - on the file, until reserving compressed space via
> - ioctl(F2FS_IOC_RESERVE_COMPRESS_BLOCKS) or truncating filesize to zero.
> + interface to reclaim compressed space and show it to user after setting a
> + special flag to the inode. Once the compressed space is released, the flag
> + will block writing data to the file until either the compressed space is
> + reserved via ioctl(F2FS_IOC_RESERVE_COMPRESS_BLOCKS) or the file size is

s/file size/filesize/

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,

> + truncated to zero.
>
> Compress metadata layout::
>
> @@ -830,12 +831,12 @@ Compress metadata layout::
> | cluster 1 | cluster 2 | ......... | cluster N |
> +-----------------------------------------------+
> . . . .
> - . . . .
> + . . . .
> . Compressed Cluster . . Normal Cluster .
> +----------+---------+---------+---------+ +---------+---------+---------+---------+
> |compr flag| block 1 | block 2 | block 3 | | block 1 | block 2 | block 3 | block 4 |
> +----------+---------+---------+---------+ +---------+---------+---------+---------+
> - . .
> + . .
> . .
> . .
> +-------------+-------------+----------+----------------------------+

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