Star64_linux/fs
Eric W. Biederman eedf265aa0 devpts: Make each mount of devpts an independent filesystem.
The /dev/ptmx device node is changed to lookup the directory entry "pts"
in the same directory as the /dev/ptmx device node was opened in.  If
there is a "pts" entry and that entry is a devpts filesystem /dev/ptmx
uses that filesystem.  Otherwise the open of /dev/ptmx fails.

The DEVPTS_MULTIPLE_INSTANCES configuration option is removed, so that
userspace can now safely depend on each mount of devpts creating a new
instance of the filesystem.

Each mount of devpts is now a separate and equal filesystem.

Reserved ttys are now available to all instances of devpts where the
mounter is in the initial mount namespace.

A new vfs helper path_pts is introduced that finds a directory entry
named "pts" in the directory of the passed in path, and changes the
passed in path to point to it.  The helper path_pts uses a function
path_parent_directory that was factored out of follow_dotdot.

In the implementation of devpts:
 - devpts_mnt is killed as it is no longer meaningful if all mounts of
   devpts are equal.
 - pts_sb_from_inode is replaced by just inode->i_sb as all cached
   inodes in the tty layer are now from the devpts filesystem.
 - devpts_add_ref is rolled into the new function devpts_ptmx.  And the
   unnecessary inode hold is removed.
 - devpts_del_ref is renamed devpts_release and reduced to just a
   deacrivate_super.
 - The newinstance mount option continues to be accepted but is now
   ignored.

In devpts_fs.h definitions for when !CONFIG_UNIX98_PTYS are removed as
they are never used.

Documentation/filesystems/devices.txt is updated to describe the current
situation.

This has been verified to work properly on openwrt-15.05, centos5,
centos6, centos7, debian-6.0.2, debian-7.9, debian-8.2, ubuntu-14.04.3,
ubuntu-15.10, fedora23, magia-5, mint-17.3, opensuse-42.1,
slackware-14.1, gentoo-20151225 (13.0?), archlinux-2015-12-01.  With the
caveat that on centos6 and on slackware-14.1 that there wind up being
two instances of the devpts filesystem mounted on /dev/pts, the lower
copy does not end up getting used.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Greg KH <greg@kroah.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Serge Hallyn <serge.hallyn@ubuntu.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Jann Horn <jann@thejh.net>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Florian Weimer <fw@deneb.enyo.de>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-05 10:36:01 -07:00
..
9p
adfs
affs affs: fix remount failure when there are no options changed 2016-05-28 16:50:24 -07:00
afs
autofs4
befs
bfs
btrfs Merge branch 'for-linus-4.7' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2016-06-04 11:56:28 -07:00
cachefiles FS-Cache: make check_consistency callback return int 2016-06-01 10:29:39 +02:00
ceph ceph: use i_version to check validity of fscache 2016-06-01 10:32:14 +02:00
cifs
coda
configfs
cramfs
crypto
debugfs
devpts devpts: Make each mount of devpts an independent filesystem. 2016-06-05 10:36:01 -07:00
dlm
ecryptfs
efivarfs
efs
exofs
exportfs
ext2
ext4
f2fs
fat
freevxfs
fscache FS-Cache: wake write waiter after invalidating writes 2016-06-01 10:29:09 +02:00
fuse
gfs2
hfs
hfsplus
hostfs
hpfs hpfs: implement the show_options method 2016-05-28 16:50:24 -07:00
hugetlbfs
isofs
jbd2
jffs2
jfs
kernfs
lockd
logfs
minix
ncpfs
nfs nfs: fix anonymous member initializer build failure with older compilers 2016-05-27 17:20:27 -07:00
nfs_common
nfsd
nilfs2
nls
notify
ntfs
ocfs2
omfs
openpromfs
orangefs
overlayfs
proc
pstore
qnx4
qnx6
quota
ramfs
reiserfs
romfs
squashfs
sysfs
sysv
tracefs
ubifs This pull request contains mostly cleanups and minor 2016-05-27 18:49:29 -07:00
udf
ufs
xfs
aio.c
anon_inodes.c
attr.c
bad_inode.c
binfmt_aout.c fs: fix binfmt_aout.c build error 2016-05-28 16:34:59 -07:00
binfmt_elf.c
binfmt_elf_fdpic.c
binfmt_em86.c
binfmt_flat.c
binfmt_misc.c
binfmt_script.c
block_dev.c
buffer.c
char_dev.c
compat.c
compat_binfmt_elf.c
compat_ioctl.c
coredump.c
dax.c
dcache.c Merge branch 'hash' of git://ftp.sciencehorizons.net/linux 2016-05-28 16:15:25 -07:00
dcookies.c
direct-io.c
drop_caches.c
eventfd.c
eventpoll.c
exec.c
fcntl.c
fhandle.c
file.c
file_table.c
filesystems.c
fs-writeback.c
fs_pin.c
fs_struct.c
inode.c
internal.h
ioctl.c
Kconfig
Kconfig.binfmt
libfs.c
locks.c
Makefile
mbcache.c
mount.h
mpage.c
namei.c devpts: Make each mount of devpts an independent filesystem. 2016-06-05 10:36:01 -07:00
namespace.c
no-block.c
nsfs.c
open.c
pipe.c
pnode.c
pnode.h
posix_acl.c
proc_namespace.c
read_write.c
readdir.c
select.c
seq_file.c
signalfd.c
splice.c
stack.c
stat.c
statfs.c
super.c
sync.c
timerfd.c
userfaultfd.c
utimes.c
xattr.c