diff options
| -rw-r--r-- | Documentation/filesystems/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/filesystems/squashfs.rst (renamed from Documentation/filesystems/squashfs.txt) | 60 |
2 files changed, 34 insertions, 27 deletions
diff --git a/Documentation/filesystems/index.rst b/Documentation/filesystems/index.rst index 3b26639517af..97a5f65ae509 100644 --- a/Documentation/filesystems/index.rst +++ b/Documentation/filesystems/index.rst @@ -86,5 +86,6 @@ Documentation for filesystem implementations. ramfs-rootfs-initramfs relay romfs + squashfs virtiofs vfat diff --git a/Documentation/filesystems/squashfs.txt b/Documentation/filesystems/squashfs.rst index e5274f84dc56..df42106bae71 100644 --- a/Documentation/filesystems/squashfs.txt +++ b/Documentation/filesystems/squashfs.rst @@ -1,7 +1,11 @@ -SQUASHFS 4.0 FILESYSTEM +.. SPDX-License-Identifier: GPL-2.0 + +======================= +Squashfs 4.0 Filesystem ======================= Squashfs is a compressed read-only filesystem for Linux. + It uses zlib, lz4, lzo, or xz compression to compress files, inodes and directories. Inodes in the system are very small and all blocks are packed to minimise data overhead. Block sizes greater than 4K are supported up to a @@ -15,31 +19,33 @@ needed. Mailing list: squashfs-devel@lists.sourceforge.net Web site: www.squashfs.org -1. FILESYSTEM FEATURES +1. Filesystem Features ---------------------- Squashfs filesystem features versus Cramfs: +============================== ========= ========== Squashfs Cramfs - -Max filesystem size: 2^64 256 MiB -Max file size: ~ 2 TiB 16 MiB -Max files: unlimited unlimited -Max directories: unlimited unlimited -Max entries per directory: unlimited unlimited -Max block size: 1 MiB 4 KiB -Metadata compression: yes no -Directory indexes: yes no -Sparse file support: yes no -Tail-end packing (fragments): yes no -Exportable (NFS etc.): yes no -Hard link support: yes no -"." and ".." in readdir: yes no -Real inode numbers: yes no -32-bit uids/gids: yes no -File creation time: yes no -Xattr support: yes no -ACL support: no no +============================== ========= ========== +Max filesystem size 2^64 256 MiB +Max file size ~ 2 TiB 16 MiB +Max files unlimited unlimited +Max directories unlimited unlimited +Max entries per directory unlimited unlimited +Max block size 1 MiB 4 KiB +Metadata compression yes no +Directory indexes yes no +Sparse file support yes no +Tail-end packing (fragments) yes no +Exportable (NFS etc.) yes no +Hard link support yes no +"." and ".." in readdir yes no +Real inode numbers yes no +32-bit uids/gids yes no +File creation time yes no +Xattr support yes no +ACL support no no +============================== ========= ========== Squashfs compresses data, inodes and directories. In addition, inode and directory data are highly compacted, and packed on byte boundaries. Each @@ -47,7 +53,7 @@ compressed inode is on average 8 bytes in length (the exact length varies on file type, i.e. regular file, directory, symbolic link, and block/char device inodes have different sizes). -2. USING SQUASHFS +2. Using Squashfs ----------------- As squashfs is a read-only filesystem, the mksquashfs program must be used to @@ -58,11 +64,11 @@ obtained from this site also. The squashfs-tools development tree is now located on kernel.org git://git.kernel.org/pub/scm/fs/squashfs/squashfs-tools.git -3. SQUASHFS FILESYSTEM DESIGN +3. Squashfs Filesystem Design ----------------------------- A squashfs filesystem consists of a maximum of nine parts, packed together on a -byte alignment: +byte alignment:: --------------- | superblock | @@ -229,15 +235,15 @@ location of the xattr list inside each inode, a 32-bit xattr id is stored. This xattr id is mapped into the location of the xattr list using a second xattr id lookup table. -4. TODOS AND OUTSTANDING ISSUES +4. TODOs and Outstanding Issues ------------------------------- -4.1 Todo list +4.1 TODO list ------------- Implement ACL support. -4.2 Squashfs internal cache +4.2 Squashfs Internal Cache --------------------------- Blocks in Squashfs are compressed. To avoid repeatedly decompressing |