Implement file operations on a regular overlay file.  The underlying file
is opened separately and cached in ->private_data.

It might be worth making an exception for such files when accounting in
nr_file to confirm to userspace expectations.  We are only adding a small
overhead (248bytes for the struct file) since the real inode and dentry are
pinned by overlayfs anyway.

This patch doesn't have any effect, since the vfs will use d_real() to find
the real underlying file to open.  The patch at the end of the series will
actually enable this functionality.

AV: make it use open_with_fake_path(), don't mess with override_creds

SzM: still need to mess with override_creds() until no fs uses
current_cred() in their open method.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Copy i_size of the underlying inode to the overlay inode in ovl_copyattr().

This is in preparation for stacking I/O operations on overlay files.

This patch shouldn't have any observable effect.

Remove stale comment from ovl_setattr() [spotted by Vivek Goyal].
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

This reverts commit 31c3a706.

Re-add functionality dealing with i_writecount on truncate to overlayfs.
This patch shouldn't have any observable effects, since we just re-assert
the writecout that vfs_truncate() already got for us.

This is in preparation for moving overlay functionality out of the VFS.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

On inode creation copy certain inode flags from the underlying real inode
to the overlay inode.

This is in preparation for moving overlay functionality out of the VFS.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Copy up mtime and ctime to overlay inode after times in real object are
modified.  Be careful not to dirty cachelines when not necessary.

This is in preparation for moving overlay functionality out of the VFS.

This patch shouldn't have any observable effect.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

This is needed by the stacked dedupe implementation in overlayfs.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

This is needed by the stacked ioctl implementation in overlayfs.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Stacking file operations in overlay will store an extra open file for each
overlay file opened.

The overhead is just that of "struct file" which is about 256bytes, because
overlay already pins an extra dentry and inode when the file is open, which
add up to a much larger overhead.

For fear of breaking working setups, don't start accounting the extra file.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Following series for stacking overlay files depends on this mini series.

Merge branch 'for-ovl' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs into overlayfs-next

This gives us the open_with_fake_path() helper that is needed for stacked
open files in overlay and mmap in particular.

Only upper dir can be impure, but if we are in the middle of
iterating a lower real dir, dir could be copied up and marked
impure. We only want the impure cache if we started iterating
a real upper dir to begin with.

Aditya Kali reported that the following reproducer hits the
WARN_ON(!cache->refcount) in ovl_get_cache():

 docker run --rm drupal:8.5.4-fpm-alpine \
    sh -c 'cd /var/www/html/vendor/symfony && \
           chown -R www-data:www-data . && ls -l .'
Reported-by: NAditya Kali <adityakali@google.com>
Tested-by: NAditya Kali <adityakali@google.com>
Fixes: 4edb83bb ('ovl: constant d_ino for non-merge dirs')
Cc: <stable@vger.kernel.org> # v4.14
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

open a file by given inode, faking ->f_path.  Use with shitloads
of caution - at the very least you'd damn better make sure that
some dentry alias of that inode is pinned down by the path in
question.  Again, this is no general-purpose interface and I hope
it will eventually go away.  Right now overlayfs wants something
like that, but nothing else should.

Any out-of-tree code with bright idea of using this one *will*
eventually get hurt, with zero notice and great delight on my part.
I refuse to use EXPORT_SYMBOL_GPL(), especially in situations when
it's really EXPORT_SYMBOL_DONT_USE_IT(), but don't take that export
as "you are welcome to use it".
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

These checks are better off in do_dentry_open(); the reason we couldn't
put them there used to be that callers couldn't tell what kind of cleanup
would do_dentry_open() failure call for.  Now that we have FMODE_OPENED,
cleanup is the same in all cases - it's simply fput().  So let's fold
that into do_dentry_open(), as Christoph's patch tried to.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Just check FMODE_OPENED in __fput() and be done with that...
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

basically, "is that instance set up enough for regular fput(), or
do we want put_filp() for that one".

NOTE: the only alloc_file() caller that could be followed by put_filp()
is in arch/ia64/kernel/perfmon.c, which is (Kconfig-level) broken.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

always equal to ->f_cred
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

... and have it set the f_flags-derived part of ->f_mode.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

... and rename get_empty_filp() to alloc_empty_file().

dentry_open() gets creds as argument, but the only thing that sees those is
security_file_open() - file->f_cred still ends up with current_cred().  For
almost all callers it's the same thing, but there are several broken cases.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

... so that it could set both ->f_flags and ->f_mode, without callers
having to set ->f_flags manually.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

An ->open() instances really, really should not be doing that.  There's
a lot of places e.g. around atomic_open() that could be confused by that,
so let's catch that early.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

... just use put_pipe_info() to get the pipe->files down to 1 and let
fput()-called pipe_release() do freeing.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

it's exactly the same thing as
	dentry_open(&file->f_path, file->f_flags, file->f_cred)

... and rename it to file_clone_open(), while we are at it.
'filp' naming convention is bogus; sure, it's "file pointer",
but we generally don't do that kind of Hungarian notation.
Some of the instances have too many callers to touch, but this
one has only two, so let's sanitize it while we can...
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

.. and the call of file_free() in case of security_file_alloc() failure
in get_empty_filp() should be simply file_free_rcu() - no point in
rcu-delays there, anyway.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Cc: stable@vger.kernel.org
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Doing iput() after path_put() is wrong.

Cc: stable@vger.kernel.org
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Failure of ->open() should *not* be followed by fput().  Fixed by
using filp_clone_open(), which gets the cleanups right.

Cc: stable@vger.kernel.org
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Extract vfs_dedupe_file_range_one() helper to deal with a single dedup
request.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

Clean up f_op->dedupe_file_range() interface.

1) Use loff_t for offsets and length instead of u64
2) Order the arguments the same way as {copy|clone}_file_range().
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>

Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Suggested-by: Darrick J. Wong <darrick.wong@oracle.com> 
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

kmemleak reported some memory leak on reading proc files. After adding
some debug lines, find that proc_seq_fops is using seq_release as
release handler, which won't handle the free of 'private' field of
seq_file, while in fact the open handler proc_seq_open could create
the private data with __seq_open_private when state_size is greater
than zero. So after reading files created with proc_create_seq_private,
such as /proc/timer_list and /proc/vmallocinfo, the private mem of a
seq_file is not freed. Fix it by adding the paired proc_seq_release
as the default release handler of proc_seq_ops instead of seq_release.

Fixes: 44414d82 ("proc: introduce proc_create_seq_private")
Reviewed-by: NChristoph Hellwig <hch@lst.de>
CC: Christoph Hellwig <hch@lst.de>
Signed-off-by: NChunyu Hu <chuhu@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Pull block fixes from Jens Axboe:
 "A collection of fixes that should go into -rc1. This contains:

   - bsg_open vs bsg_unregister race fix (Anatoliy)

   - NVMe pull request from Christoph, with fixes for regressions in
     this window, FC connect/reconnect path code unification, and a
     trace point addition.

   - timeout fix (Christoph)

   - remove a few unused functions (Christoph)

   - blk-mq tag_set reinit fix (Roman)"

* tag 'for-linus-20180616' of git://git.kernel.dk/linux-block:
  bsg: fix race of bsg_open and bsg_unregister
  block: remov blk_queue_invalidate_tags
  nvme-fabrics: fix and refine state checks in __nvmf_check_ready
  nvme-fabrics: handle the admin-only case properly in nvmf_check_ready
  nvme-fabrics: refactor queue ready check
  blk-mq: remove blk_mq_tagset_iter
  nvme: remove nvme_reinit_tagset
  nvme-fc: fix nulling of queue data on reconnect
  nvme-fc: remove reinit_request routine
  blk-mq: don't time out requests again that are in the timeout handler
  nvme-fc: change controllers first connect to use reconnect path
  nvme: don't rely on the changed namespace list log
  nvmet: free smart-log buffer after use
  nvme-rdma: fix error flow during mapping request data
  nvme: add bio remapping tracepoint
  nvme: fix NULL pointer dereference in nvme_init_subsystem
  blk-mq: reinit q->tag_set_list entry only after grace period

Pull documentation fixes from Mauro Carvalho Chehab:
 "This solves a series of broken links for files under Documentation,
  and improves a script meant to detect such broken links (see
  scripts/documentation-file-ref-check).

  The changes on this series are:

   - can.rst: fix a footnote reference;

   - crypto_engine.rst: Fix two parsing warnings;

   - Fix a lot of broken references to Documentation/*;

   - improve the scripts/documentation-file-ref-check script, in order
     to help detecting/fixing broken references, preventing
     false-positives.

  After this patch series, only 33 broken references to doc files are
  detected by scripts/documentation-file-ref-check"

* tag 'docs-broken-links' of git://linuxtv.org/mchehab/experimental: (26 commits)
  fix a series of Documentation/ broken file name references
  Documentation: rstFlatTable.py: fix a broken reference
  ABI: sysfs-devices-system-cpu: remove a broken reference
  devicetree: fix a series of wrong file references
  devicetree: fix name of pinctrl-bindings.txt
  devicetree: fix some bindings file names
  MAINTAINERS: fix location of DT npcm files
  MAINTAINERS: fix location of some display DT bindings
  kernel-parameters.txt: fix pointers to sound parameters
  bindings: nvmem/zii: Fix location of nvmem.txt
  docs: Fix more broken references
  scripts/documentation-file-ref-check: check tools/*/Documentation
  scripts/documentation-file-ref-check: get rid of false-positives
  scripts/documentation-file-ref-check: hint: dash or underline
  scripts/documentation-file-ref-check: add a fix logic for DT
  scripts/documentation-file-ref-check: accept more wildcards at filenames
  scripts/documentation-file-ref-check: fix help message
  media: max2175: fix location of driver's companion documentation
  media: v4l: fix broken video4linux docs locations
  media: dvb: point to the location of the old README.dvb-usb file
  ...

Pull fsnotify updates from Jan Kara:
 "fsnotify cleanups unifying handling of different watch types.

  This is the shortened fsnotify series from Amir with the last five
  patches pulled out. Amir has modified those patches to not change
  struct inode but obviously it's too late for those to go into this
  merge window"

* tag 'fsnotify_for_v4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  fsnotify: add fsnotify_add_inode_mark() wrappers
  fanotify: generalize fanotify_should_send_event()
  fsnotify: generalize send_to_group()
  fsnotify: generalize iteration of marks by object type
  fsnotify: introduce marks iteration helpers
  fsnotify: remove redundant arguments to handle_event()
  fsnotify: use type id to identify connector object type

Pull fbdev updates from Bartlomiej Zolnierkiewicz:
 "There is nothing really major here, few small fixes, some cleanups and
  dead drivers removal:

   - mark omapfb drivers as orphans in MAINTAINERS file (Tomi Valkeinen)

   - add missing module license tags to omap/omapfb driver (Arnd
     Bergmann)

   - add missing GPIOLIB dependendy to omap2/omapfb driver (Arnd
     Bergmann)

   - convert savagefb, aty128fb & radeonfb drivers to use msleep & co.
     (Jia-Ju Bai)

   - allow COMPILE_TEST build for viafb driver (media part was reviewed
     by media subsystem Maintainer)

   - remove unused MERAM support from sh_mobile_lcdcfb and shmob-drm
     drivers (drm parts were acked by shmob-drm driver Maintainer)

   - remove unused auo_k190xfb drivers

   - misc cleanups (Souptick Joarder, Wolfram Sang, Markus Elfring, Andy
     Shevchenko, Colin Ian King)"

* tag 'fbdev-v4.18' of git://github.com/bzolnier/linux: (26 commits)
  fb_omap2: add gpiolib dependency
  video/omap: add module license tags
  MAINTAINERS: make omapfb orphan
  video: fbdev: pxafb: match_string() conversion fixup
  video: fbdev: nvidia: fix spelling mistake: "scaleing" -> "scaling"
  video: fbdev: fix spelling mistake: "frambuffer" -> "framebuffer"
  video: fbdev: pxafb: Convert to use match_string() helper
  video: fbdev: via: allow COMPILE_TEST build
  video: fbdev: remove unused sh_mobile_meram driver
  drm: shmobile: remove unused MERAM support
  video: fbdev: sh_mobile_lcdcfb: remove unused MERAM support
  video: fbdev: remove unused auo_k190xfb drivers
  video: omap: Improve a size determination in omapfb_do_probe()
  video: sm501fb: Improve a size determination in sm501fb_probe()
  video: fbdev-MMP: Improve a size determination in path_init()
  video: fbdev-MMP: Delete an error message for a failed memory allocation in two functions
  video: auo_k190x: Delete an error message for a failed memory allocation in auok190x_common_probe()
  video: sh_mobile_lcdcfb: Delete an error message for a failed memory allocation in two functions
  video: sh_mobile_meram: Delete an error message for a failed memory allocation in sh_mobile_meram_probe()
  video: fbdev: sh_mobile_meram: Drop SUPERH platform dependency
  ...