v4.19.13 snapshot.
diff --git a/Documentation/filesystems/adfs.txt b/Documentation/filesystems/adfs.txt
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+Mount options for ADFS
+----------------------
+
+ uid=nnn All files in the partition will be owned by
+ user id nnn. Default 0 (root).
+ gid=nnn All files in the partition will be in group
+ nnn. Default 0 (root).
+ ownmask=nnn The permission mask for ADFS 'owner' permissions
+ will be nnn. Default 0700.
+ othmask=nnn The permission mask for ADFS 'other' permissions
+ will be nnn. Default 0077.
+ ftsuffix=n When ftsuffix=0, no file type suffix will be applied.
+ When ftsuffix=1, a hexadecimal suffix corresponding to
+ the RISC OS file type will be added. Default 0.
+
+Mapping of ADFS permissions to Linux permissions
+------------------------------------------------
+
+ ADFS permissions consist of the following:
+
+ Owner read
+ Owner write
+ Other read
+ Other write
+
+ (In older versions, an 'execute' permission did exist, but this
+ does not hold the same meaning as the Linux 'execute' permission
+ and is now obsolete).
+
+ The mapping is performed as follows:
+
+ Owner read -> -r--r--r--
+ Owner write -> --w--w---w
+ Owner read and filetype UnixExec -> ---x--x--x
+ These are then masked by ownmask, eg 700 -> -rwx------
+ Possible owner mode permissions -> -rwx------
+
+ Other read -> -r--r--r--
+ Other write -> --w--w--w-
+ Other read and filetype UnixExec -> ---x--x--x
+ These are then masked by othmask, eg 077 -> ----rwxrwx
+ Possible other mode permissions -> ----rwxrwx
+
+ Hence, with the default masks, if a file is owner read/write, and
+ not a UnixExec filetype, then the permissions will be:
+
+ -rw-------
+
+ However, if the masks were ownmask=0770,othmask=0007, then this would
+ be modified to:
+ -rw-rw----
+
+ There is no restriction on what you can do with these masks. You may
+ wish that either read bits give read access to the file for all, but
+ keep the default write protection (ownmask=0755,othmask=0577):
+
+ -rw-r--r--
+
+ You can therefore tailor the permission translation to whatever you
+ desire the permissions should be under Linux.
+
+RISC OS file type suffix
+------------------------
+
+ RISC OS file types are stored in bits 19..8 of the file load address.
+
+ To enable non-RISC OS systems to be used to store files without losing
+ file type information, a file naming convention was devised (initially
+ for use with NFS) such that a hexadecimal suffix of the form ,xyz
+ denoted the file type: e.g. BasicFile,ffb is a BASIC (0xffb) file. This
+ naming convention is now also used by RISC OS emulators such as RPCEmu.
+
+ Mounting an ADFS disc with option ftsuffix=1 will cause appropriate file
+ type suffixes to be appended to file names read from a directory. If the
+ ftsuffix option is zero or omitted, no file type suffixes will be added.