Commit 7cbb468f authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab Committed by Jonathan Corbet

docs: filesystems: convert omfs.txt to ReST

- Add a SPDX header;
- Adjust document title;
- Mark literal blocks as such;
- Add table markups;
- Add it to filesystems/index.rst.
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
Acked-by: default avatarBob Copeland <me@bobcopeland.com>
Link: https://lore.kernel.org/r/0c125c7c971d81a557ca954992b8d770a9d1e3e8.1581955849.git.mchehab+huawei@kernel.orgSigned-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent fa95e087
......@@ -78,6 +78,7 @@ Documentation for filesystem implementations.
ntfs
ocfs2
ocfs2-online-filecheck
omfs
overlayfs
virtiofs
vfat
.. SPDX-License-Identifier: GPL-2.0
================================
Optimized MPEG Filesystem (OMFS)
================================
Overview
========
......@@ -29,11 +33,13 @@ Options
OMFS supports the following mount-time options:
uid=n - make all files owned by specified user
gid=n - make all files owned by specified group
umask=xxx - set permission umask to xxx
fmask=xxx - set umask to xxx for files
dmask=xxx - set umask to xxx for directories
============ ========================================
uid=n make all files owned by specified user
gid=n make all files owned by specified group
umask=xxx set permission umask to xxx
fmask=xxx set umask to xxx for files
dmask=xxx set umask to xxx for directories
============ ========================================
Disk format
===========
......@@ -46,9 +52,9 @@ have a smaller size than a data block, but since they are both addressed by the
same 64-bit block number, any remaining space in the smaller sysblock is
unused.
Sysblock header information:
Sysblock header information::
struct omfs_header {
struct omfs_header {
__be64 h_self; /* FS block where this is located */
__be32 h_body_size; /* size of useful data after header */
__be16 h_crc; /* crc-ccitt of body_size bytes */
......@@ -58,11 +64,11 @@ struct omfs_header {
u8 h_magic; /* OMFS_IMAGIC */
u8 h_check_xor; /* XOR of header bytes before this */
__be32 h_fill2;
};
};
Files and directories are both represented by omfs_inode:
Files and directories are both represented by omfs_inode::
struct omfs_inode {
struct omfs_inode {
struct omfs_header i_head; /* header */
__be64 i_parent; /* parent containing this inode */
__be64 i_sibling; /* next inode in hash bucket */
......@@ -73,7 +79,7 @@ struct omfs_inode {
char i_fill3[64];
char i_name[OMFS_NAMELEN]; /* filename */
__be64 i_size; /* size of file, in bytes */
};
};
Directories in OMFS are implemented as a large hash table. Filenames are
hashed then prepended into the bucket list beginning at OMFS_DIR_START.
......@@ -82,19 +88,19 @@ until a match is found on i_name. Empty buckets are represented by block
pointers with all-1s (~0).
A file is an omfs_inode structure followed by an extent table beginning at
OMFS_EXTENT_START:
OMFS_EXTENT_START::
struct omfs_extent_entry {
struct omfs_extent_entry {
__be64 e_cluster; /* start location of a set of blocks */
__be64 e_blocks; /* number of blocks after e_cluster */
};
};
struct omfs_extent {
struct omfs_extent {
__be64 e_next; /* next extent table location */
__be32 e_extent_count; /* total # extents in this table */
__be32 e_fill;
struct omfs_extent_entry e_entry; /* start of extent entries */
};
};
Each extent holds the block offset followed by number of blocks allocated to
the extent. The final extent in each table is a terminator with e_cluster
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment