Re: [PATCH v2] docs: filesystems: f2fs: fix description about compress ioctl

From: Matthew Wilcox
Date: Sun Jun 12 2022 - 23:37:18 EST


On Mon, Jun 13, 2022 at 10:08:00AM +0800, Chao Liu wrote:
> v2:
> - s/file size/filesize/

Why would you change it to be wrong?

> 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..531b0f8a3946 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 filesize is
> + 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 |
> +----------+---------+---------+---------+ +---------+---------+---------+---------+
> - . .
> + . .
> . .
> . .
> +-------------+-------------+----------+----------------------------+
> --
> 2.36.1
>