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 switch xattr_handler->set() to passing dentry and inode separately 2016-05-27 15:39:43 -04:00
adfs fs/adfs/adfs.h: tidy up comments 2016-01-20 17:09:18 -08:00
affs affs: fix remount failure when there are no options changed 2016-05-28 16:50:24 -07:00
afs remove lots of IS_ERR_VALUE abuses 2016-05-27 15:26:11 -07:00
autofs4 dcache_{readdir,dir_lseek}() users: switch to ->iterate_shared 2016-05-02 19:49:32 -04:00
befs fs/befs/io.c:befs_bread(): remove unneeded initialization to NULL 2016-05-23 17:04:14 -07:00
bfs more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
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 switch xattr_handler->set() to passing dentry and inode separately 2016-05-27 15:39:43 -04:00
coda introduce a parallel variant of ->iterate() 2016-05-02 19:49:29 -04:00
configfs configfs_readdir(): make safe under shared lock 2016-05-09 11:41:13 -04:00
cramfs more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
crypto fscrypto/f2fs: allow fs-specific key prefix for fs encryption 2016-05-07 10:32:33 -07:00
debugfs Merge 4.6-rc4 into driver-core-next 2016-04-19 04:28:28 +09:00
devpts devpts: Make each mount of devpts an independent filesystem. 2016-06-05 10:36:01 -07:00
dlm mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
ecryptfs switch ->setxattr() to passing dentry and inode separately 2016-05-27 20:09:16 -04:00
efivarfs fs/efivarfs/inode.c: use generic UUID library 2016-05-20 17:58:30 -07:00
efs fs/efs/super.c: fix return value 2016-05-20 17:58:30 -07:00
exofs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2016-05-17 17:05:30 -07:00
exportfs introduce a parallel variant of ->iterate() 2016-05-02 19:49:29 -04:00
ext2 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-05-27 17:14:05 -07:00
ext4 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-05-27 17:14:05 -07:00
f2fs switch xattr_handler->set() to passing dentry and inode separately 2016-05-27 15:39:43 -04:00
fat Merge branch 'work.preadv2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-05-17 15:05:23 -07:00
freevxfs more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
fscache FS-Cache: wake write waiter after invalidating writes 2016-06-01 10:29:09 +02:00
fuse switch ->setxattr() to passing dentry and inode separately 2016-05-27 20:09:16 -04:00
gfs2 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-05-27 17:14:05 -07:00
hfs switch ->setxattr() to passing dentry and inode separately 2016-05-27 20:09:16 -04:00
hfsplus switch xattr_handler->set() to passing dentry and inode separately 2016-05-27 15:39:43 -04:00
hostfs hostfs: switch to ->iterate_shared() 2016-05-12 19:49:30 -04:00
hpfs hpfs: implement the show_options method 2016-05-28 16:50:24 -07:00
hugetlbfs mm, fs: remove remaining PAGE_CACHE_* and page_cache_{get,release} usage 2016-04-04 10:41:08 -07:00
isofs Merge branch 'ovl-fixes' into for-linus 2016-05-11 00:00:29 -04:00
jbd2 Fix a number of bugs, most notably a potential stale data exposure 2016-05-24 12:55:26 -07:00
jffs2 switch xattr_handler->set() to passing dentry and inode separately 2016-05-27 15:39:43 -04:00
jfs switch xattr_handler->set() to passing dentry and inode separately 2016-05-27 15:39:43 -04:00
kernfs switch ->setxattr() to passing dentry and inode separately 2016-05-27 20:09:16 -04:00
lockd lockd: constify nlmsvc_binding structure 2016-01-07 10:10:50 -05:00
logfs logfs: no need to lock directory in lseek 2016-05-09 11:42:19 -04:00
minix simple local filesystems: switch to ->iterate_shared() 2016-05-02 19:49:32 -04:00
ncpfs mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
nfs nfs: fix anonymous member initializer build failure with older compilers 2016-05-27 17:20:27 -07:00
nfs_common
nfsd A very quiet cycle for nfsd, mainly just an RDMA update from Chuck Lever. 2016-05-24 14:39:20 -07:00
nilfs2 nilfs2: fix block comments 2016-05-23 17:04:14 -07:00
nls
notify fsnotify: avoid spurious EMFILE errors from inotify_init() 2016-05-19 19:12:14 -07:00
ntfs fs: simplify the generic_write_sync prototype 2016-05-01 19:58:39 -04:00
ocfs2 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-05-27 17:14:05 -07:00
omfs more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
openpromfs more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
orangefs switch xattr_handler->set() to passing dentry and inode separately 2016-05-27 15:39:43 -04:00
overlayfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-05-27 17:14:05 -07:00
proc mm, proc: make clear_refs killable 2016-05-23 17:04:14 -07:00
pstore mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
qnx4 more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
qnx6 more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
quota fs/quota: use nla_put_u64_64bit() 2016-04-26 12:00:48 -04:00
ramfs tmpfs/ramfs: fix VM_MAYSHARE mappings for NOMMU 2016-05-20 17:58:30 -07:00
reiserfs switch xattr_handler->set() to passing dentry and inode separately 2016-05-27 15:39:43 -04:00
romfs romfs, squashfs: switch to ->iterate_shared() 2016-05-09 11:41:15 -04:00
squashfs romfs, squashfs: switch to ->iterate_shared() 2016-05-09 11:41:15 -04:00
sysfs
sysv simple local filesystems: switch to ->iterate_shared() 2016-05-02 19:49:32 -04:00
tracefs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
ubifs This pull request contains mostly cleanups and minor 2016-05-27 18:49:29 -07:00
udf Merge branch 'work.preadv2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-05-17 15:05:23 -07:00
ufs simple local filesystems: switch to ->iterate_shared() 2016-05-02 19:49:32 -04:00
xfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-05-27 17:14:05 -07:00
aio.c aio: make aio_setup_ring killable 2016-05-23 17:04:14 -07:00
anon_inodes.c
attr.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
bad_inode.c switch ->setxattr() to passing dentry and inode separately 2016-05-27 20:09:16 -04:00
binfmt_aout.c fs: fix binfmt_aout.c build error 2016-05-28 16:34:59 -07:00
binfmt_elf_fdpic.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-05-18 11:51:59 -07:00
binfmt_elf.c mm: remove more IS_ERR_VALUE abuses 2016-05-27 15:57:31 -07:00
binfmt_em86.c
binfmt_flat.c remove lots of IS_ERR_VALUE abuses 2016-05-27 15:26:11 -07:00
binfmt_misc.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
binfmt_script.c
block_dev.c DAX error handling for 4.7 2016-05-26 19:34:26 -07:00
buffer.c mm, page_alloc: avoid looking up the first zone in a zonelist twice 2016-05-19 19:12:14 -07:00
char_dev.c chrdev: emit a warning when we go below dynamic major range 2016-03-29 10:11:44 -07:00
compat_binfmt_elf.c
compat_ioctl.c Merge 4.5-rc4 into char-misc-next 2016-02-14 14:25:59 -08:00
compat.c Fix a number of bugs, most notably a potential stale data exposure 2016-05-24 12:55:26 -07:00
coredump.c coredump: make coredump_wait wait for mmap_sem for write killable 2016-05-23 17:04:14 -07:00
dax.c Filesystem DAX locking for 4.7 2016-05-26 20:00:28 -07:00
dcache.c Merge branch 'hash' of git://ftp.sciencehorizons.net/linux 2016-05-28 16:15:25 -07:00
dcookies.c
direct-io.c direct-io: fix direct write stale data exposure from concurrent buffered read 2016-05-27 14:49:37 -07:00
drop_caches.c
eventfd.c eventfd: document lockless access in eventfd_poll 2016-03-22 15:36:02 -07:00
eventpoll.c fs: poll/select/recvmmsg: use timespec64 for timeout events 2016-05-19 19:12:14 -07:00
exec.c exec: make exec path waiting for mmap_sem killable 2016-05-23 17:04:14 -07:00
fcntl.c fcntl: allow to set O_DIRECT flag on pipe 2016-01-09 02:55:37 -05:00
fhandle.c fs/coredump: prevent fsuid=0 dumps into user-controlled directories 2016-03-22 15:36:02 -07:00
file_table.c
file.c give readdir(2)/getdents(2)/etc. uniform exclusion with lseek() 2016-05-02 19:49:28 -04:00
filesystems.c find_filesystem(): simplify comparison 2016-01-19 12:02:23 -05:00
fs_pin.c
fs_struct.c
fs-writeback.c mm,writeback: don't use memory reserves for wb_start_writeback 2016-05-20 17:58:30 -07:00
inode.c parallel lookups: actual switch to rwsem 2016-05-02 19:49:28 -04:00
internal.h Merge branch 'for-linus' into work.misc 2016-01-08 21:20:11 -05:00
ioctl.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
Kconfig dax: Make huge page handling depend of CONFIG_BROKEN 2016-05-19 15:13:17 -06:00
Kconfig.binfmt ELF/MIPS build fix 2016-05-23 17:04:14 -07:00
libfs.c switch ->setxattr() to passing dentry and inode separately 2016-05-27 20:09:16 -04:00
locks.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
Makefile Merge tag 'ofs-pull-tag-1' of git://git.kernel.org/pub/scm/linux/kernel/git/hubcap/linux 2016-03-26 12:59:04 -07:00
mbcache.c mbcache: add reusable flag to cache entries 2016-02-22 22:44:04 -05:00
mount.h
mpage.c mm, fs: remove remaining PAGE_CACHE_* and page_cache_{get,release} usage 2016-04-04 10:41:08 -07:00
namei.c devpts: Make each mount of devpts an independent filesystem. 2016-06-05 10:36:01 -07:00
namespace.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
no-block.c
nsfs.c
open.c Merge branch 'work.const-path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-05-17 14:41:03 -07:00
pipe.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
pnode.c propogate_mnt: Handle the first propogated copy being a slave 2016-05-05 09:54:45 -05:00
pnode.h
posix_acl.c switch xattr_handler->set() to passing dentry and inode separately 2016-05-27 15:39:43 -04:00
proc_namespace.c vfs: show_vfsstat: do not ignore errors from show_devname method 2016-03-16 13:09:08 -04:00
read_write.c Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-05-18 11:46:23 -07:00
readdir.c restore killability of old mutex_lock_killable(&inode->i_mutex) users 2016-05-26 00:13:25 -04:00
select.c fs: poll/select/recvmmsg: use timespec64 for timeout events 2016-05-19 19:12:14 -07:00
seq_file.c Make file credentials available to the seqfile interfaces 2016-04-14 12:56:09 -07:00
signalfd.c
splice.c Merge branch 'ovl-fixes' into for-linus 2016-05-11 00:00:29 -04:00
stack.c
stat.c fs/stat.c: drop the last new_valid_dev check 2016-01-16 11:17:23 -08:00
statfs.c
super.c Merge branch 'master' into for-next 2016-04-18 11:18:55 +02:00
sync.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
timerfd.c timerfd: Handle relative timers with CONFIG_TIME_LOW_RES proper 2016-01-17 11:13:55 +01:00
userfaultfd.c userfaultfd: don't pin the user memory in userfaultfd_file_create() 2016-05-20 17:58:30 -07:00
utimes.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
xattr.c switch ->setxattr() to passing dentry and inode separately 2016-05-27 20:09:16 -04:00