commit bbd84f33652f852ce5992d65db4d020aba21f882 upstream.

Starting from commit 9c225f26 ("vfs: atomic f_pos accesses as per
POSIX") files opened even via nonseekable_open gate read and write via lock
and do not allow them to be run simultaneously. This can create read vs
write deadlock if a filesystem is trying to implement a socket-like file
which is intended to be simultaneously used for both read and write from
filesystem client.  See commit 10dce8af3422 ("fs: stream_open - opener for
stream-like files so that read and write can run simultaneously without
deadlock") for details and e.g. commit 581d21a2 ("xenbus: fix deadlock
on writes to /proc/xen/xenbus") for a similar deadlock example on
/proc/xen/xenbus.

To avoid such deadlock it was tempting to adjust fuse_finish_open to use
stream_open instead of nonseekable_open on just FOPEN_NONSEEKABLE flags,
but grepping through Debian codesearch shows users of FOPEN_NONSEEKABLE,
and in particular GVFS which actually uses offset in its read and write
handlers

	https://codesearch.debian.net/search?q=-%3Enonseekable+%3D
	https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1080
	https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1247-1346
	https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1399-1481

so if we would do such a change it will break a real user.

Add another flag (FOPEN_STREAM) for filesystem servers to indicate that the
opened handler is having stream-like semantics; does not use file position
and thus the kernel is free to issue simultaneous read and write request on
opened file handle.

This patch together with stream_open() should be added to stable kernels
starting from v3.14+. This will allow to patch OSSPD and other FUSE
filesystems that provide stream-like files to return FOPEN_STREAM |
FOPEN_NONSEEKABLE in open handler and this way avoid the deadlock on all
kernel versions. This should work because fuse_finish_open ignores unknown
open flags returned from a filesystem and so passing FOPEN_STREAM to a
kernel that is not aware of this flag cannot hurt. In turn the kernel that
is not aware of FOPEN_STREAM will be < v3.14 where just FOPEN_NONSEEKABLE
is sufficient to implement streams without read vs write deadlock.

Cc: stable@vger.kernel.org # v3.14+
Signed-off-by: NKirill Smelkov <kirr@nexedi.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Currently the userspace has no way of knowing whether the fuse
connection ended because of umount or abort via sysfs. It makes it hard
for filesystems to free the mountpoint after abort without worrying
about removing some new mount.

The patch fixes it by returning different errors when userspace reads
from /dev/fuse (-ENODEV for umount and -ECONNABORTED for abort).

Add a new capability flag FUSE_ABORT_ERROR. If set and the connection is
gone because of sysfs abort, reading from the device will return
-ECONNABORTED.
Signed-off-by: NSzymon Lukasz <noh4hss@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Many user space API headers have licensing information, which is either
incomplete, badly formatted or just a shorthand for referring to the
license under which the file is supposed to be.  This makes it hard for
compliance tools to determine the correct license.

Update these files with an SPDX license identifier.  The identifier was
chosen based on the license information in the file.

GPL/LGPL licensed headers get the matching GPL/LGPL SPDX license
identifier with the added 'WITH Linux-syscall-note' exception, which is
the officially assigned exception identifier for the kernel syscall
exception:

   NOTE! This copyright does *not* cover user programs that use kernel
   services by normal system calls - this is merely considered normal use
   of the kernel, and does *not* fall under the heading of "derived work".

This exception makes it possible to include GPL headers into non GPL
code, without confusing license compliance tools.

Headers which have either explicit dual licensing or are just licensed
under a non GPL license are updated with the corresponding SPDX
identifier and the GPLv2 with syscall exception identifier.  The format
is:
        ((GPL-2.0 WITH Linux-syscall-note) OR SPDX-ID-OF-OTHER-LICENSE)

SPDX license identifiers are a legally binding shorthand, which can be
used instead of the full boiler plate text.  The update does not remove
existing license information as this has to be done on a case by case
basis and the copyright holders might have to be consulted. This will
happen in a separate step.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.  See the previous patch in this series for the
methodology of how this patch was researched.
Reviewed-by: NKate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: NPhilippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add a new INIT flag, FUSE_POSIX_ACL, for negotiating ACL support with
userspace.  When it is set in the INIT response, ACL support will be
enabled.  ACL support also implies "default_permissions".

When ACL support is enabled, the kernel will cache and have responsibility
for enforcing ACLs.  ACL xattrs will be passed to userspace, which is
responsible for updating the ACLs in the filesystem, keeping the file mode
in sync, and inheritance of default ACLs when new filesystem nodes are
created.
Signed-off-by: NSeth Forshee <seth.forshee@canonical.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Only userspace filesystem can do the killing of suid/sgid without races.
So introduce an INIT flag and negotiate support for this.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Negotiate with userspace filesystems whether they support parallel readdir
and lookup.  Disable parallelism by default for fear of breaking fuse
filesystems.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Fixes: 9902af79 ("parallel lookups: actual switch to rwsem")
Fixes: d9b3dbdc ("fuse: switch to ->iterate_shared()")

A useful performance improvement for accessing virtual machine images
via FUSE mount.

See https://bugzilla.redhat.com/show_bug.cgi?id=1220173 for a use-case
for glusterFS.
Signed-off-by: NRavishankar N <ravishankar@redhat.com>
Signed-off-by: NMiklos Szeredi <miklos@szeredi.hu>

Allow an open fuse device to be "cloned".  Userspace can create a clone by:

      newfd = open("/dev/fuse", O_RDWR)
      ioctl(newfd, FUSE_DEV_IOC_CLONE, &oldfd);

At this point newfd will refer to the same fuse connection as oldfd.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Reviewed-by: NAshish Samant <ashish.samant@oracle.com>

Here some additional changes to set a capability flag so that clients can
detect when it's appropriate to return -ENOSYS from open.

This amends the following commit introduced in 3.14:

  7678ac50  fuse: support clients that don't implement 'open'

However we can only add the flag to 3.15 and later since there was no
protocol version update in 3.14.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Cc: <stable@vger.kernel.org> # v3.15+

Support RENAME_EXCHANGE and RENAME_NOREPLACE flags on the userspace ABI.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

The patch extends fuse_setattr_in, and extends the flush procedure
(fuse_flush_times()) called on ->write_inode() to send the ctime as well as
mtime.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Allow userspace fs to specify time granularity.

This is needed because with writeback_cache mode the kernel is responsible
for generating mtime and ctime, but if the underlying filesystem doesn't
support nanosecond granularity then the cache will contain a different
value from the one stored on the filesystem resulting in a change of times
after a cache flush.

Make the default granularity 1s.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Introduce a bit kernel and userspace exchange between each-other on
the init stage and turn writeback on if the userspace want this and
mount option 'allow_wbcache' is present (controlled by fusermount).

Also add each writable file into per-inode write list and call the
generic_file_aio_write to make use of the Linux page cache engine.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Without async DIO write requests to a single file were always serialized.
With async DIO that's no longer the case.

So don't turn on async DIO by default for fear of breaking backward
compatibility.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Commit 7e98d530 (Synchronize fuse header with
one used in library) added #ifdef __linux__ around defines if it is not set.
The kernel build is self-contained and can be built on non-Linux toolchains.
After the mentioned commit builds on non-Linux toolchains will try to include
stdint.h and fail due to -nostdinc, and then fail with a bunch of undefined type
errors.

Fix by checking for __KERNEL__ instead of __linux__ and using the standard int
types instead of the linux specific ones.
Reported-by: NArve Hjønnevåg <arve@android.com>
Reported-by: NColin Cross <ccross@android.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

For some filesystems (e.g. GlusterFS), the cost of performing a
normal readdir and readdirplus are identical.  Since adaptively
using readdirplus has no benefit for those systems, give
users/filesystems the option to control adaptive readdirplus use.

v2 of this patch incorporates Miklos's suggestion to simplify the code,
as well as improving consistency of macro names and documentation.
Signed-off-by: NEric Wong <normalperson@yhbt.net>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

The library one has provisions for use in *BSD, add them to the kernel one too.
They don't hurt and ease maintenance.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

commit 626cf236 "poll: add poll_requested_events()..." enabled us to send the
requested events to the filesystem.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Yeah, we have a capability flag for this as well, so this is not strictly
necessary, but it doesn't hurt either.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

This patch implements readdirplus support in FUSE, similar to NFS.
The payload returned in the readdirplus call contains
'fuse_entry_out' structure thereby providing all the necessary inputs
for 'faking' a lookup() operation on the spot.

If the dentry and inode already existed (for e.g. in a re-run of ls -l)
then just the inode attributes timeout and dentry timeout are refreshed.

With a simple client->network->server implementation of a FUSE based
filesystem, the following performance observations were made:

Test: Performing a filesystem crawl over 20,000 files with

sh# time ls -lR /mnt

Without readdirplus:
Run 1: 18.1s
Run 2: 16.0s
Run 3: 16.2s

With readdirplus:
Run 1: 4.1s
Run 2: 3.8s
Run 3: 3.8s

The performance improvement is significant as it avoided 20,000 upcalls
calls (lookup). Cache consistency is no worse than what already is.
Signed-off-by: NAnand V. Avati <avati@redhat.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NMichael Kerrisk <mtk.manpages@gmail.com>
Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: NDave Jones <davej@redhat.com>

Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Add missing flags that userspace derived from the protocol version number.  This
makes the protocol more flexible.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

FUSE_AUTO_INVAL_DATA is provided to enable updated/auto cache
invalidation logic.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

fallocate filesystem operation preallocates media space for the given file.
If fallocate returns success then any subsequent write to the given range
never fails with 'not enough space' error.
Signed-off-by: NAnatol Pomozov <anatol.pomozov@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Use the ISO C standard compliant form instead of the gcc extension in the
interface definition.
Reported-by: NShachar Sharon <ssnail@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Allows a FUSE file-system to tell the kernel when a file or directory is
deleted. If the specified dentry has the specified inode number, the kernel will
unhash it.

The current 'fuse_notify_inval_entry' does not cause the kernel to clean up
directories that are in use properly, and as a result the users of those
directories see incorrect semantics from the file-system. The error condition
seen when 'fuse_notify_inval_entry' is used to notify of a deleted directory is
avoided when 'fuse_notify_delete' is used instead.

The following scenario demonstrates the difference:
1. User A chdirs into 'testdir' and starts reading 'testfile'.
2. User B rm -rf 'testdir'.
3. User B creates 'testdir'.
4. User C chdirs into 'testdir'.

If you run the above within the same machine on any file-system (including fuse
file-systems), there is no problem: user C is able to chdir into the new
testdir. The old testdir is removed from the dentry tree, but still open by user
A.

If operations 2 and 3 are performed via the network such that the fuse
file-system uses one of the notify functions to tell the kernel that the nodes
are gone, then the following error occurs for user C while user A holds the
original directory open:

muirj@empacher:~> ls /test/testdir
ls: cannot access /test/testdir: No such file or directory

The issue here is that the kernel still has a dentry for testdir, and so it is
requesting the attributes for the old directory, while the file-system is
responding that the directory no longer exists.

If on the other hand, if the file-system can notify the kernel that the
directory is deleted using the new 'fuse_notify_delete' function, then the above
ls will find the new directory as expected.
Signed-off-by: NJohn Muir <john@jmuir.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Multiplexing filesystems may want to support ioctls on the underlying
files and directores (e.g. FS_IOC_{GET,SET}FLAGS).

Ioctl support on directories was missing so add it now.
Reported-by: NAntonio SJ Musumeci <bile@landofbile.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Commit a9ff4f87 "fuse: support BSD locking semantics" overlooked a
number of issues with supporing flock locks over existing POSIX
locking infrastructure:

  - it's not backward compatible, passing flock(2) calls to userspace
    unconditionally (if userspace sets FUSE_POSIX_LOCKS)

  - it doesn't cater for the fact that flock locks are automatically
    unlocked on file release

  - it doesn't take into account the fact that flock exclusive locks
    (write locks) don't need an fd opened for write.

The last one invalidates the original premise of the patch that flock
locks can be emulated with POSIX locks.

This patch fixes the first two issues.  The last one needs to be fixed
in userspace if the filesystem assumed that a write lock will happen
only on a file operned for write (as in the case of the current fuse
library).
Reported-by: NSebastian Pipping <webmaster@hartwork.org>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

In kernel ABI version 7.16 and later FUSE_IOCTL_RETRY reply from a
unrestricted IOCTL request shall return with an array of 'struct
fuse_ioctl_iovec' instead of 'struct iovec'.  This fixes the ABI
ambiguity of 32bit vs. 64bit.
Reported-by: N"ccmail111" <ccmail111@yahoo.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
CC: Tejun Heo <tj@kernel.org>

Terje Malmedal reports that a fuse filesystem with 32 million inodes
on a machine with lots of memory can take up to 30 minutes to process
FORGET requests when all those inodes are evicted from the icache.

To solve this, create a BATCH_FORGET request that allows up to about
8000 FORGET requests to be sent in a single message.

This request is only sent if userspace supports interface version 7.16
or later, otherwise fall back to sending individual FORGET messages.
Reported-by: NTerje Malmedal <terje.malmedal@usit.uio.no>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Userspace filesystem can request data to be retrieved from the inode's
mapping.  This request is synchronous and the retrieved data is queued
as a new request.  If the write to the fuse device returns an error
then the retrieve request was not completed and a reply will not be
sent.

Only present pages are returned in the retrieve reply.  Retrieving
stops when it finds a non-present page and only data prior to that is
returned.

This request doesn't change the dirty state of pages.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Userspace filesystem can request data to be stored in the inode's
mapping.  This request is synchronous and has no reply.  If the write
to the fuse device returns an error then the store request was not
fully completed (but may have updated some pages).

If the stored data overflows the current file size, then the size is
extended, similarly to a write(2) on the filesystem.

Pages which have been completely stored are marked uptodate.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Allow userspace filesystem implementation to use splice() to write to
the fuse device.  The semantics of using splice() are:

 1) buffer the message header and data in a temporary pipe
 2) with a *single* splice() call move the message from the temporary pipe
    to the fuse device

The READ reply message has the most interesting use for this, since
now the data from an arbitrary file descriptor (which could be a
regular file, a block device or a socket) can be tranferred into the
fuse device without having to go through a userspace buffer.  It will
also allow zero copy moving of pages.

One caveat is that the protocol on the fuse device requires the length
of the whole message to be written into the header.  But the length of
the data transferred into the temporary pipe may not be known in
advance.  The current library implementation works around this by
using vmplice to write the header and modifying the header after
splicing the data into the pipe (error handling omitted):

	struct fuse_out_header out;

	iov.iov_base = &out;
	iov.iov_len = sizeof(struct fuse_out_header);
	vmsplice(pip[1], &iov, 1, 0);
	len = splice(input_fd, input_offset, pip[1], NULL, len, 0);
	/* retrospectively modify the header: */
	out.len = len + sizeof(struct fuse_out_header);
	splice(pip[0], NULL, fuse_chan_fd(req->ch), NULL, out.len, flags);

This works since vmsplice only saves a pointer to the data, it does
not copy the data itself.

Since pipes are currently limited to 16 pages and messages need to be
spliced atomically, the length of the data is limited to 15 pages (or
60kB for 4k pages).
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Clarify how the protocol version should be negotiated between kernel
and userspace.  Notably libfuse didn't correctly handle the case when
the supported major versions didn't match.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

The practical values for these limits depend on the design of the
filesystem server so let userspace set them at initialization time.
Signed-off-by: NCsaba Henk <csaba@gluster.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Add notification messages that allow the filesystem to invalidate VFS
caches.

Two notifications are added:

 1) inode invalidation

   - invalidate cached attributes
   - invalidate a range of pages in the page cache (this is optional)

 2) dentry invalidation

   - try to invalidate a subtree in the dentry cache

Care must be taken while accessing the 'struct super_block' for the
mount, as it can go away while an invalidation is in progress.  To
prevent this, introduce a rw-semaphore, that is taken for read during
the invalidation and taken for write in the ->kill_sb callback.

Cc: Csaba Henk <csaba@gluster.com>
Cc: Anand Avati <avati@zresearch.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

This patch lets filesystems handle masking the file mode on creation.
This is needed if filesystem is using ACLs.

 - The CREATE, MKDIR and MKNOD requests are extended with a "umask"
   parameter.

 - A new FUSE_DONT_MASK flag is added to the INIT request/reply.  With
   this the filesystem may request that the create mode is not masked.

CC: Jean-Pierre André <jean-pierre.andre@wanadoo.fr>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

CUSE enables implementing character devices in userspace.  With recent
additions of ioctl and poll support, FUSE already has most of what's
necessary to implement character devices.  All CUSE has to do is
bonding all those components - FUSE, chardev and the driver model -
nicely.

When client opens /dev/cuse, kernel starts conversation with
CUSE_INIT.  The client tells CUSE which device it wants to create.  As
the previous patch made fuse_file usable without associated
fuse_inode, CUSE doesn't create super block or inodes.  It attaches
fuse_file to cdev file->private_data during open and set ff->fi to
NULL.  The rest of the operation is almost identical to FUSE direct IO
case.

Each CUSE device has a corresponding directory /sys/class/cuse/DEVNAME
(which is symlink to /sys/devices/virtual/class/DEVNAME if
SYSFS_DEPRECATED is turned off) which hosts "waiting" and "abort"
among other things.  Those two files have the same meaning as the FUSE
control files.

The only notable lacking feature compared to in-kernel implementation
is mmap support.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Change interface version to 7.11 after adding the IOCTL and POLL
messages.

Also clean up the <linux/fuse.h> header a bit:
  - update copyright date to 2008
  - fix checkpatch warning:
      WARNING: Use #include <linux/types.h> instead of <asm/types.h>
  - remove FUSE_MAJOR define, which is not being used any more
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>