From daa22ae91b75f8c4692f6802dcb514dca08752ff Mon Sep 17 00:00:00 2001 From: Erez Zadok Date: Tue, 21 Jan 2014 03:10:11 -0500 Subject: [PATCH] Wrapfs: update documentation Signed-off-by: Erez Zadok --- Documentation/filesystems/wrapfs.txt | 32 ++++++++++++++++------------ 1 file changed, 18 insertions(+), 14 deletions(-) diff --git a/Documentation/filesystems/wrapfs.txt b/Documentation/filesystems/wrapfs.txt index f61879a20a26..a189903f92c8 100644 --- a/Documentation/filesystems/wrapfs.txt +++ b/Documentation/filesystems/wrapfs.txt @@ -7,28 +7,32 @@ Web Site: MOTIVATION: Wrapfs is a small null-layer stackable file system, similar to BSD's Nullfs. -Wrapfs is small, under 1800 lines of code. Compare that to, say, eCryptfs -and Unionfs, each of which are over 10,000 LoC. As such, Wrapfs is simple -and easy to read and understand. Wrapfs is useful for several reasons: +Wrapfs is small, under 1,800 lines of code. Compare that to, say, eCryptfs +(in mainline since 2.6.19) and Unionfs, each of which are over 10,000 LoC. +As such, Wrapfs is simple, easy to read and understand, and very easy to +code-review. Wrapfs is useful for several reasons: -1. Many people like to experiment with in-kernel file system ideas as a - prototype; Wrapfs is an ideal small template from which one could modify - the code to create new file system functionality incrementally. +1. Many people like to experiment with in-kernel file system ideas. Wrapfs + is an ideal small template that one can modify to incrementally create + new file system functionalities. 2. As a platform to test and debug generic stacking problems in other Linux - stackable file systems (e.g., ecryptfs). + stackable file systems (e.g., eCryptfs) more easily. 3. As a way to test VFS enhancements to better support stacking in Linux. -4. Wrapfs is a very useful instructional tool, often used as a starting - point for course assignments, for people who want a small example of who - the Linux VFS works, or for those who want to learn to write new Linux - file systems. +4. Wrapfs is also a very useful instructional tool, often used as a starting + point for course assignments, for people who want a small example of how + the Linux VFS works, or for those who want to learn how to write new + Linux file systems. Various versions of Wrapfs appeared as part of the "fistgen" package since -1994, and have been used by numerous users world-wide. For a more detailed -history of Wrapfs, and list of most of its known users, see the section -marked "HISTORY" below. +1994, and have been used by numerous users world-wide. This latest version +was rewritten entirely from scratch in 2010 and had supported every kernel +as of 2.6.32. All versions of wrapfs have been thoroughly tested using LTP, +FSX, racer, and other test-suites. Wrapfs code uses the latest VFS API +changes of the corresponding kernel. For a more detailed history of Wrapfs, +and list of most of its known users, see the section marked "HISTORY" below. ------------------------------------------------------------------------------ OPERATION: -- 2.43.0