This is a note to let you know that I've just added the patch titled
f2fs: document: add description about compressed space handling
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
f2fs-document-add-description-about-compressed-space.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 8a86857d41240a18f01b22fa83f2ee6d8bc5777a
Author: Chao Yu <chao@xxxxxxxxxx>
Date: Tue Apr 13 17:56:53 2021 +0800
f2fs: document: add description about compressed space handling
[ Upstream commit 38740707c5bc1253069eb932bc6d244f80ec21f0 ]
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 <yuchao0@xxxxxxxxxx>
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
Stable-dep-of: 7e1b150fece0 ("f2fs: compress: fix to avoid redundant compress extension")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
index 4f51c0be22c45..9e302d3dd85a6 100644
--- a/Documentation/filesystems/f2fs.rst
+++ b/Documentation/filesystems/f2fs.rst
@@ -803,6 +803,14 @@ 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::
