From 38740707c5bc1253069eb932bc6d244f80ec21f0 Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Tue, 13 Apr 2021 17:56:53 +0800 Subject: [PATCH] f2fs: document: add description about compressed space handling User or developer may still be confused about why f2fs doesn't expose compressed space to userspace, add description about compressed space handling policy into f2fs documentation. Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim --- Documentation/filesystems/f2fs.rst | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst index 63c0c49b726d..992bf91eeec8 100644 --- a/Documentation/filesystems/f2fs.rst +++ b/Documentation/filesystems/f2fs.rst @@ -819,6 +819,14 @@ Compression implementation * chattr +c file * chattr +c dir; touch dir/file * mount w/ -o compress_extension=ext; touch file.ext + * mount w/ -o compress_extension=*; touch any_file + +- At this point, compression feature doesn't expose compressed space to user + directly in order to guarantee potential data updates later to the space. + 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 interface to reclaim compressed + space and show it to user after putting the immutable bit. Compress metadata layout:: -- 2.20.1