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mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-23 04:34:11 +08:00
linux-next/Documentation/filesystems
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
..
caching FS-Cache: Count the number of initialised operations 2015-04-02 14:28:53 +01:00
cifs Documentation: fix common spelling mistakes 2016-04-28 07:51:59 -06:00
configfs configfs: switch ->default groups to a linked list 2016-03-06 16:11:24 +01:00
nfs Various bugfixes, a RDMA update from Chuck Lever, and support for a new 2016-03-24 19:50:32 -07:00
pohmelfs Documentation: fix common spelling mistakes 2016-04-28 07:51:59 -06:00
.gitignore Documentation: update .gitignore files 2014-09-26 11:02:59 +02:00
9p.txt 9p: update documentation 2014-01-24 10:55:21 -06:00
00-INDEX dax: replace XIP documentation with DAX documentation 2015-02-16 17:56:03 -08:00
adfs.txt
affs.txt affs: add mount option to avoid filename truncates 2014-04-07 16:36:08 -07:00
afs.txt
autofs4-mount-control.txt doc: fix double words 2014-03-21 13:16:58 +01:00
autofs4.txt autofs: the documentation I wanted to read 2014-10-14 02:18:17 +02:00
automount-support.txt Documentation: remove outdated information from automount-support.txt 2015-05-15 01:10:38 -04:00
befs.txt
bfs.txt
btrfs.txt Documentation: btrfs: remove usage specific information 2016-03-11 17:02:09 +01:00
ceph.txt
coda.txt
cramfs.txt mm, fs: remove remaining PAGE_CACHE_* and page_cache_{get,release} usage 2016-04-04 10:41:08 -07:00
dax.txt dax: for truncate/hole-punch, do zeroing through the driver if possible 2016-05-18 12:16:57 -06:00
debugfs.txt debugfs: Pass bool pointer to debugfs_create_bool() 2015-10-04 11:36:07 +01:00
devpts.txt devpts: Make each mount of devpts an independent filesystem. 2016-06-05 10:36:01 -07:00
directory-locking update D/f/directory-locking 2016-05-26 00:04:18 -04:00
dlmfs.txt ocfs2: update web page + git tree in documentation 2015-02-28 09:57:50 -08:00
dnotify_test.c
dnotify.txt
ecryptfs.txt
efivarfs.txt efi: Make efivarfs entries immutable by default 2016-02-10 16:25:52 +00:00
exofs.txt
ext2.txt fs: Remove ext3 filesystem driver 2015-07-23 20:59:40 +02:00
ext3.txt fs: Remove ext3 filesystem driver 2015-07-23 20:59:40 +02:00
ext4.txt ext4: add DAX functionality 2015-02-16 17:56:04 -08:00
f2fs.txt f2fs: introduce new option for controlling data flush 2015-12-16 09:25:48 -08:00
fiemap.txt fsioctl.c: make generic_block_fiemap() signal-tolerant 2015-02-10 14:30:30 -08:00
files.txt
fuse.txt
gfs2-glocks.txt gfs2: Remove gl_spin define 2015-10-29 12:57:48 -05:00
gfs2-uevents.txt
gfs2.txt
hfs.txt
hfsplus.txt Documentation: update URL to hfsplus Technote 1150 2014-02-20 14:48:51 +01:00
hpfs.txt
inotify.txt inotify: update documentation to reflect code changes 2015-02-10 14:30:28 -08:00
isofs.txt
jfs.txt doc: fix misspellings with 'codespell' tool 2013-05-28 12:02:12 +02:00
Locking direct-io: eliminate the offset argument to ->direct_IO 2016-05-01 19:58:39 -04:00
locks.txt
logfs.txt
Makefile configfs: remove old API 2015-10-13 22:17:57 -07:00
mandatory-locking.txt
ncpfs.txt
nilfs2.txt nilfs2: clarify permission to replicate the design 2016-05-23 17:04:14 -07:00
ntfs.txt NTFS: Remove changelog from Documentation/filesystems/ntfs.txt. 2014-10-16 12:43:57 +01:00
ocfs2-online-filecheck.txt ocfs2: add feature document for online file check 2016-03-22 15:36:02 -07:00
ocfs2.txt ocfs2: update web page + git tree in documentation 2015-02-28 09:57:50 -08:00
omfs.txt
orangefs.txt Orangefs: update orangefs.txt 2016-02-26 14:39:08 -05:00
overlayfs.txt ovl: update documentation 2016-05-27 08:55:26 +02:00
path-lookup.md Documentation: add new description of path-name lookup. 2015-11-02 18:18:25 -07:00
path-lookup.txt Documentation: add new description of path-name lookup. 2015-11-02 18:18:25 -07:00
porting switch ->setxattr() to passing dentry and inode separately 2016-05-27 20:09:16 -04:00
proc.txt procfs: expose umask in /proc/<PID>/status 2016-05-20 17:58:30 -07:00
qnx6.txt Documentation: fix common spelling mistakes 2016-04-28 07:51:59 -06:00
quota.txt quota: Update documentation 2015-05-18 11:23:07 +02:00
ramfs-rootfs-initramfs.txt initmpfs: use initramfs if rootfstype= or root= specified 2013-09-11 15:59:38 -07:00
relay.txt doc: Fix typo in doucmentations 2013-07-25 12:34:15 +02:00
romfs.txt
seq_file.txt Documentation: update seq_file 2014-12-29 15:40:18 -07:00
sharedsubtree.txt doc: fix grammar 2016-03-09 15:33:06 -07:00
spufs.txt
squashfs.txt Squashfs: Add LZ4 compression configuration option 2014-11-27 18:48:44 +00:00
sysfs-pci.txt
sysfs-tagging.txt sysfs-tagging.txt: fix pre-kernfs references 2015-09-13 14:38:51 -06:00
sysfs.txt sysfs.txt: mention that store method buffers are null-terminated 2015-09-13 14:38:51 -06:00
sysv-fs.txt
tmpfs.txt mm, fs: remove remaining PAGE_CACHE_* and page_cache_{get,release} usage 2016-04-04 10:41:08 -07:00
ubifs.txt
udf.txt
ufs.txt
vfat.txt fat: add config option to set UTF-8 mount option by default 2016-03-22 15:36:02 -07:00
vfs.txt direct-io: eliminate the offset argument to ->direct_IO 2016-05-01 19:58:39 -04:00
xfs-delayed-logging-design.txt
xfs-self-describing-metadata.txt xfs: add metadata CRC documentation 2013-04-27 13:27:43 -05:00
xfs.txt xfs: fix kernel version in docs 2015-06-01 07:15:38 +10:00