Squashfs: Update documentation to include compression options
Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>
diff --git a/Documentation/filesystems/squashfs.txt b/Documentation/filesystems/squashfs.txt
index 66699af..2d78f19 100644
--- a/Documentation/filesystems/squashfs.txt
+++ b/Documentation/filesystems/squashfs.txt
@@ -59,12 +59,15 @@
3. SQUASHFS FILESYSTEM DESIGN
-----------------------------
-A squashfs filesystem consists of a maximum of eight parts, packed together on a byte
-alignment:
+A squashfs filesystem consists of a maximum of nine parts, packed together on a
+byte alignment:
---------------
| superblock |
|---------------|
+ | compression |
+ | options |
+ |---------------|
| datablocks |
| & fragments |
|---------------|
@@ -91,7 +94,14 @@
written the completed inode, directory, fragment, export and uid/gid lookup
tables are written.
-3.1 Inodes
+3.1 Compression options
+-----------------------
+
+Compressors can optionally support compression specific options (e.g.
+dictionary size). If non-default compression options have been used, then
+these are stored here.
+
+3.2 Inodes
----------
Metadata (inodes and directories) are compressed in 8Kbyte blocks. Each
@@ -114,7 +124,7 @@
regular files and directories, and extended types where extra
information has to be stored.
-3.2 Directories
+3.3 Directories
---------------
Like inodes, directories are packed into compressed metadata blocks, stored
@@ -144,7 +154,7 @@
This scheme has the advantage that it doesn't require extra memory overhead
and doesn't require much extra storage on disk.
-3.3 File data
+3.4 File data
-------------
Regular files consist of a sequence of contiguous compressed blocks, and/or a
@@ -163,7 +173,7 @@
The index cache is designed to be memory efficient, and by default uses
16 KiB.
-3.4 Fragment lookup table
+3.5 Fragment lookup table
-------------------------
Regular files can contain a fragment index which is mapped to a fragment
@@ -173,7 +183,7 @@
speed of access (and because it is small) is read at mount time and cached
in memory.
-3.5 Uid/gid lookup table
+3.6 Uid/gid lookup table
------------------------
For space efficiency regular files store uid and gid indexes, which are
@@ -182,7 +192,7 @@
locate these. This second index table for speed of access (and because it
is small) is read at mount time and cached in memory.
-3.6 Export table
+3.7 Export table
----------------
To enable Squashfs filesystems to be exportable (via NFS etc.) filesystems
@@ -196,7 +206,7 @@
used to locate these. This second index table for speed of access (and because
it is small) is read at mount time and cached in memory.
-3.7 Xattr table
+3.8 Xattr table
---------------
The xattr table contains extended attributes for each inode. The xattrs