linux-stable.git/Documentation/filesystems, branch v4.7

devpts: Make each mount of devpts an independent filesystem.

2016-06-05T17:36:01+00:00

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" 
Cc: Greg KH 
Cc: Peter Hurley 
Cc: Peter Anvin 
Cc: Andy Lutomirski 
Cc: Al Viro 
Cc: Serge Hallyn 
Cc: Willy Tarreau 
Cc: Aurelien Jarno 
Cc: One Thousand Gnomes 
Cc: Jann Horn 
Cc: Jiri Slaby 
Cc: Florian Weimer 
Cc: Konstantin Khlebnikov 
Signed-off-by: Linus Torvalds

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2016-05-28T00:14:05+00:00

Pull vfs fixes from Al Viro:
 "Followups to the parallel lookup work:

   - update docs

   - restore killability of the places that used to take ->i_mutex
     killably now that we have down_write_killable() merged

   - Additionally, it turns out that I missed a prerequisite for
     security_d_instantiate() stuff - ->getxattr() wasn't the only thing
     that could be called before dentry is attached to inode; with smack
     we needed the same treatment applied to ->setxattr() as well"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  switch ->setxattr() to passing dentry and inode separately
  switch xattr_handler->set() to passing dentry and inode separately
  restore killability of old mutex_lock_killable(&inode->i_mutex) users
  add down_write_killable_nested()
  update D/f/directory-locking

switch ->setxattr() to passing dentry and inode separately

2016-05-28T00:09:16+00:00

smack ->d_instantiate() uses ->setxattr(), so to be able to call it before
we'd hashed the new dentry and attached it to inode, we need ->setxattr()
instances getting the inode as an explicit argument rather than obtaining
it from dentry.

Similar change for ->getxattr() had been done in commit ce23e64.  Unlike
->getxattr() (which is used by both selinux and smack instances of
->d_instantiate()) ->setxattr() is used only by smack one and unfortunately
it got missed back then.

Reported-by: Seung-Woo Kim 
Tested-by: Casey Schaufler 
Signed-off-by: Al Viro

Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

2016-05-27T23:44:39+00:00

Pull overlayfs update from Miklos Szeredi:
 "The meat of this is a change to use the mounter's credentials for
  operations that require elevated privileges (such as whiteout
  creation).  This fixes behavior under user namespaces as well as being
  a nice cleanup"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: Do d_type check only if work dir creation was successful
  ovl: update documentation
  ovl: override creds with the ones from the superblock mounter

ovl: update documentation

2016-05-27T06:55:26+00:00

Two "fixme" items are actually fixed now.

Signed-off-by: Miklos Szeredi

Merge tag 'dax-misc-for-4.7' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

2016-05-27T02:34:26+00:00

Pull misc DAX updates from Vishal Verma:
 "DAX error handling for 4.7

   - Until now, dax has been disabled if media errors were found on any
     device.  This enables the use of DAX in the presence of these
     errors by making all sector-aligned zeroing go through the driver.

   - The driver (already) has the ability to clear errors on writes that
     are sent through the block layer using 'DSMs' defined in ACPI 6.1.

  Other misc changes:

   - When mounting DAX filesystems, check to make sure the partition is
     page aligned.  This is a requirement for DAX, and previously, we
     allowed such unaligned mounts to succeed, but subsequent
     reads/writes would fail.

   - Misc/cleanup fixes from Jan that remove unused code from DAX
     related to zeroing, writeback, and some size checks"

* tag 'dax-misc-for-4.7' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  dax: fix a comment in dax_zero_page_range and dax_truncate_page
  dax: for truncate/hole-punch, do zeroing through the driver if possible
  dax: export a low-level __dax_zero_page_range helper
  dax: use sb_issue_zerout instead of calling dax_clear_sectors
  dax: enable dax in the presence of known media errors (badblocks)
  dax: fallback from pmd to pte on error
  block: Update blkdev_dax_capable() for consistency
  xfs: Add alignment check for DAX mount
  ext2: Add alignment check for DAX mount
  ext4: Add alignment check for DAX mount
  block: Add bdev_dax_supported() for dax mount checks
  block: Add vfs_msg() interface
  dax: Remove redundant inode size checks
  dax: Remove pointless writeback from dax_do_io()
  dax: Remove zeroing from dax_io()
  dax: Remove dead zeroing code from fault handlers
  ext2: Avoid DAX zeroing to corrupt data
  ext2: Fix block zeroing in ext2_get_blocks() for DAX
  dax: Remove complete_unwritten argument
  DAX: move RADIX_DAX_ definitions to dax.c

update D/f/directory-locking

2016-05-26T04:04:18+00:00

Signed-off-by: Al Viro

nilfs2: clarify permission to replicate the design

2016-05-24T00:04:14+00:00

To respond to a certain developer's request, this explicitly state that
developers can reimplement the nilfs2 design for other operating systems
to share data stored in that format.

Link: http://lkml.kernel.org/r/1461935747-10380-7-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Ryusuke Konishi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

procfs: expose umask in /proc//status

2016-05-21T00:58:30+00:00

It's not possible to read the process umask without also modifying it,
which is what umask(2) does.  A library cannot read umask safely,
especially if the main program might be multithreaded.

Add a new status line ("Umask") in /proc//status.  It contains the
file mode creation mask (umask) in octal.  It is only shown for tasks
which have task->fs.

This patch is adapted from one originally written by Pierre Carrier.

The use case is that we have endless trouble with people setting weird
umask() values (usually on the grounds of "security"), and then
everything breaking.  I'm on the hook to fix these.  We'd like to add
debugging to our program so we can dump out the umask in debug reports.

Previous versions of the patch used a syscall so you could only read
your own umask.  That's all I need.  However there was quite a lot of
push-back from those, so this new version exports it in /proc.

See:
  https://lkml.org/lkml/2016/4/13/704 [umask2]
  https://lkml.org/lkml/2016/4/13/487 [getumask]

Signed-off-by: Richard W.M. Jones 
Acked-by: Konstantin Khlebnikov 
Acked-by: Jerome Marchand 
Acked-by: Kees Cook 
Cc: "Theodore Ts'o" 
Cc: Michal Hocko 
Cc: Pierre Carrier 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'docs-for-linus' of git://git.lwn.net/linux

2016-05-20T01:07:25+00:00

Pull Documentation updates from Jon Corbet:
 "A bit busier this time around.

  The most interesting thing (IMO) this time around is some beginning
  infrastructural work to allow documents to be written using
  restructured text.  Maybe someday, in a galaxy far far away, we'll be
  able to eliminate the DocBook dependency and have a much better
  integrated set of kernel docs.  Someday.

  Beyond that, there's a new document on security hardening from Kees,
  the movement of some sample code over to samples/, a number of
  improvements to the serial docs from Geert, and the usual collection
  of corrections, typo fixes, etc"

* tag 'docs-for-linus' of git://git.lwn.net/linux: (55 commits)
  doc: self-protection: provide initial details
  serial: doc: Use port->state instead of info
  serial: doc: Always refer to tty_port->mutex
  Documentation: vm: Spelling s/paltform/platform/g
  Documentation/memcg: update kmem limit doc as codes behavior
  docproc: print a comment about autogeneration for rst output
  docproc: add support for reStructuredText format via --rst option
  docproc: abstract terminating lines at first space
  docproc: abstract docproc directive detection
  docproc: reduce unnecessary indentation
  docproc: add variables for subcommand and filename
  kernel-doc: use rst C domain directives and references for types
  kernel-doc: produce RestructuredText output
  kernel-doc: rewrite usage description, remove duplicated comments
  Doc: correct the location of sysrq.c
  Documentation: fix common spelling mistakes
  samples: v4l: from Documentation to samples directory
  samples: connector: from Documentation to samples directory
  Documentation: xillybus: fix spelling mistake
  Documentation: x86: fix spelling mistakes
  ...