linux/Documentation/filesystems
Miklos Szeredi f84e3f521e mount options: add documentation
This series addresses the problem of showing mount options in
/proc/mounts.

Several filesystems which use mount options, have not implemented a
.show_options superblock operation.  Several others have implemented
this callback, but have not kept it fully up to date with the parsed
options.

Q: Why do we need correct option showing in /proc/mounts?
A: We want /proc/mounts to fully replace /etc/mtab.  The reasons for
   this are:
    - unprivileged mounters won't be able to update /etc/mtab
    - /etc/mtab doesn't work with private mount namespaces
    - /etc/mtab can become out-of-sync with reality

Q: Can't this be done, so that filesystems need not bother with
   implementing a .show_mounts callback, and keeping it up to date?
A: Only in some cases.  Certain filesystems allow modification of a
   subset of options in their remount_fs method.  It is not possible
   to take this into account without knowing exactly how the
   filesystem handles options.

For the simple case (no remount or remount resets all options) the
patchset introduces two helpers:

  generic_show_options()
  save_mount_options()

These can also be used to emulate the old /etc/mtab behavior, until
proper support is added.  Even if this is not 100% correct, it's still
better than showing no options at all.

The following patches fix up most in-tree filesystems, some have been
compile tested only, some have been reviewed and acked by the
maintainer.

Table displaying status of all in-kernel filesystems:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
legend:

  none - fs has options, but doesn't define ->show_options()
  some - fs defines ->show_options(), but some only options are shown
  good - fs shows all options
  noopt - fs does not have options
  patch - a patch will be posted
  merged - a patch has been merged by subsystem maintainer

9p          good
adfs        patch
affs        patch
afs         patch
autofs      patch
autofs4     patch
befs        patch
bfs         noopt
cifs        some
coda        noopt
configfs    noopt
cramfs      noopt
debugfs     noopt
devpts      patch
ecryptfs    good
efs         noopt
ext2        patch
ext3        good
ext4        merged
fat         patch
freevxfs    noopt
fuse        patch
fusectl	    noopt
gfs2        good
gfs2meta    noopt
hfs         good
hfsplus     good
hostfs      patch
hpfs        patch
hppfs       noopt
hugetlbfs   patch
isofs       patch
jffs2       noopt
jfs         merged
minix       noopt
msdos       ->fat
ncpfs       patch
nfs         some
nfsd        noopt
ntfs        good
ocfs2       good
ocfs2/dlmfs noopt
openpromfs  noopt
proc        noopt
qnx4        noopt
ramfs       noopt
reiserfs    patch
romfs       noopt
smbfs       good
sysfs       noopt
sysv        noopt
udf         patch
ufs         good
vfat        ->fat
xfs         good

mm/shmem.c                                    patch
drivers/oprofile/oprofilefs.c                 noopt
drivers/infiniband/hw/ipath/ipath_fs.c        noopt
drivers/misc/ibmasm/ibmasmfs.c                noopt
drivers/usb/core (usbfs)                      merged
drivers/usb/gadget (gadgetfs)                 noopt
drivers/isdn/capi/capifs.c                    patch
kernel/cpuset.c                               noopt
fs/binfmt_misc.c                              noopt
net/sunrpc/rpc_pipe.c                         noopt
arch/powerpc/platforms/cell/spufs             patch
arch/s390/hypfs                               good
ipc/mqueue.c                                  noopt
security (securityfs)                         noopt
security/selinux/selinuxfs.c                  noopt
kernel/cgroup.c                               good
security/smack/smackfs.c                      noopt

in -mm:

reiser4     some
unionfs     good
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

This patch:

Document the rules for handling mount options in the .show_options
super operation.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-08 09:22:39 -08:00
..
configfs correct missing a double quote in configfs.txt 2008-02-03 16:10:08 +02:00
00-INDEX Documentation: move sharedsubtrees.txt to filesystems/ 2008-02-07 08:42:17 -08:00
9p.txt 9p: add virtio transport 2007-10-23 13:47:31 -05:00
Exporting exportfs: update documentation 2007-10-22 08:13:21 -07:00
Locking iget: remove iget() and the read_inode() super op as being obsolete 2008-02-07 08:42:29 -08:00
adfs.txt Fix typos in /Documentation : 'U-Z' 2006-11-30 04:58:40 +01:00
affs.txt [PATCH] kernel Doc/ URL corrections 2005-11-22 09:14:30 -08:00
afs.txt [AFS]: Update the AFS fs documentation. 2007-04-26 15:57:43 -07:00
automount-support.txt VFS: Unexport do_kern_mount() and clean up simple_pin_fs() 2006-06-09 09:34:16 -04:00
befs.txt Fix typos in Documentation/: 'Q'-'R' 2006-10-03 22:54:15 +02:00
bfs.txt [PATCH] update Tigran's email addresses 2006-12-13 09:05:53 -08:00
cifs.txt Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
coda.txt Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
cramfs.txt Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
dentry-locking.txt [PATCH] VFS: split dentry locking documentation 2005-11-07 07:53:56 -08:00
directory-locking Documentation: Fix up docs still talking about i_sem 2007-05-24 10:16:17 -07:00
dlmfs.txt Fix typos in Documentation/: 'D'-'E' 2006-10-03 22:47:42 +02:00
dnotify.txt Documentation: move dnotify.txt to filesystems/ 2008-02-07 08:42:17 -08:00
ecryptfs.txt eCryptfs: Move ecryptfs docs into Documentation/filesystems/ 2007-07-17 10:23:08 -07:00
ext2.txt Fix typos in Documentation/: 'N'-'P' 2006-10-03 22:52:05 +02:00
ext3.txt documentation/ext3: grammar fixes 2007-10-20 02:38:36 +02:00
ext4.txt ext4: Add multi block allocator for ext4 2008-01-29 00:19:52 -05:00
files.txt Documentation/filesystems/files.txt: remove rcuref_inc_lf() reverences 2007-10-20 01:47:49 +02:00
fuse.txt [PATCH] fuse: fix typo 2006-12-30 10:56:45 -08:00
gfs2.txt [GFS2] Update documentation 2006-04-25 15:44:04 -04:00
hfs.txt Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
hfsplus.txt Documentation: document HFSPlus 2007-07-31 15:39:38 -07:00
hpfs.txt misc doc and kconfig typos 2007-05-09 08:58:15 +02:00
inotify.txt [PATCH] inotify (5/5): update kernel documentation 2006-06-20 05:25:19 -04:00
isofs.txt isofs: implement dmode option 2008-02-08 09:22:38 -08:00
jfs.txt JFS: document uid, gid, and umask mount options in jfs.txt 2007-03-09 10:27:31 -06:00
locks.txt Documentation: move locks.txt in filesystems/ 2007-10-09 18:32:45 -04:00
mandatory-locking.txt locks: add warning about mandatory locking races 2007-10-09 18:32:45 -04:00
ncpfs.txt Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
ntfs.txt NTFS: Fix a mount time deadlock. 2007-10-12 09:16:30 -07:00
ocfs2.txt [PATCH 2/2] ocfs2: cluster aware flock() 2008-01-25 15:05:43 -08:00
porting iget: remove iget() and the read_inode() super op as being obsolete 2008-02-07 08:42:29 -08:00
proc.txt get rid of NR_OPEN and introduce a sysctl_nr_open 2008-02-06 10:41:06 -08:00
quota.txt quota: send messages via netlink 2007-10-17 08:42:56 -07:00
ramfs-rootfs-initramfs.txt Documentation: fix type error 2008-02-03 14:50:11 +02:00
relay.txt doc: use correct debugfs mountpoint 2008-02-03 16:30:51 +02:00
romfs.txt Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
sharedsubtree.txt Documentation: move sharedsubtrees.txt to filesystems/ 2008-02-07 08:42:17 -08:00
smbfs.txt Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
spufs.txt Fix typos in /Documentation : 'U-Z' 2006-11-30 04:58:40 +01:00
sysfs-pci.txt Fix typos concerning hierarchy 2007-02-17 19:23:03 +01:00
sysfs.txt docs/sysfs: add missing word to sysfs attribute explanation 2007-10-20 02:39:43 +02:00
sysv-fs.txt [PATCH] fs/sysv/: doc cleanup 2006-12-07 08:39:44 -08:00
tmpfs.txt mount -t tmpfs -o mpol=: check nodes online 2007-06-08 17:23:32 -07:00
udf.txt [PATCH] Update udf documentation to reflect current state of read/write support 2006-11-16 11:43:38 -08:00
ufs.txt [PATCH] ufs2 write: mount as rw 2007-02-12 09:48:40 -08:00
vfat.txt fat: don't use free_clusters for fat32 2007-05-08 11:15:13 -07:00
vfs.txt mount options: add documentation 2008-02-08 09:22:39 -08:00
xfs.txt [XFS] Update XFS documentation. 2005-11-03 13:46:43 +11:00
xip.txt misc doc and kconfig typos 2007-05-09 08:58:15 +02:00