linux.git/fs/fuse, branch v5.4-rc2

Merge tag 'virtio-fs-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse

2019-09-27T22:54:24+00:00

Pull fuse virtio-fs support from Miklos Szeredi:
 "Virtio-fs allows exporting directory trees on the host and mounting
  them in guest(s).

  This isn't actually a new filesystem, but a glue layer between the
  fuse filesystem and a virtio based back-end.

  It's similar in functionality to the existing virtio-9p solution, but
  significantly faster in benchmarks and has better POSIX compliance.
  Further permformance improvements can be achieved by sharing the page
  cache between host and guest, allowing for faster I/O and reduced
  memory use.

  Kata Containers have been including the out-of-tree virtio-fs (with
  the shared page cache patches as well) since version 1.7 as an
  experimental feature. They have been active in development and plan to
  switch from virtio-9p to virtio-fs as their default solution. There
  has been interest from other sources as well.

  The userspace infrastructure is slated to be merged into qemu once the
  kernel part hits mainline.

  This was developed by Vivek Goyal, Dave Gilbert and Stefan Hajnoczi"

* tag 'virtio-fs-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
  virtio-fs: add virtiofs filesystem
  virtio-fs: add Documentation/filesystems/virtiofs.rst
  fuse: reserve values for mapping protocol

fuse: Make fuse_args_to_req static

2019-09-24T13:28:02+00:00

Fix sparse warning:

fs/fuse/dev.c:468:6: warning: symbol 'fuse_args_to_req' was not declared. Should it be static?

Reported-by: Hulk Robot 
Signed-off-by: YueHaibing 
Fixes: 68583165f962 ("fuse: add pages to fuse_args")
Signed-off-by: Miklos Szeredi

fuse: fix memleak in cuse_channel_open

2019-09-24T13:28:01+00:00

If cuse_send_init fails, need to fuse_conn_put cc->fc.

cuse_channel_open->fuse_conn_init->refcount_set(&fc->count, 1)
                 ->fuse_dev_alloc->fuse_conn_get
                 ->fuse_dev_free->fuse_conn_put

Fixes: cc080e9e9be1 ("fuse: introduce per-instance fuse_dev structure")
Reported-by: Hulk Robot 
Signed-off-by: zhengbin 
Signed-off-by: Miklos Szeredi

fuse: fix beyond-end-of-page access in fuse_parse_cache()

2019-09-24T13:28:01+00:00

With DEBUG_PAGEALLOC on, the following triggers.

  BUG: unable to handle page fault for address: ffff88859367c000
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 3001067 P4D 3001067 PUD 406d3a8067 PMD 406d30c067 PTE 800ffffa6c983060
  Oops: 0000 [#1] SMP DEBUG_PAGEALLOC
  CPU: 38 PID: 3110657 Comm: python2.7
  RIP: 0010:fuse_readdir+0x88f/0xe7a [fuse]
  Code: 49 8b 4d 08 49 39 4e 60 0f 84 44 04 00 00 48 8b 43 08 43 8d 1c 3c 4d 01 7e 68 49 89 dc 48 03 5c 24 38 49 89 46 60 8b 44 24 30 <8b> 4b 10 44 29 e0 48 89 ca 48 83 c1 1f 48 83 e1 f8 83 f8 17 49 89
  RSP: 0018:ffffc90035edbde0 EFLAGS: 00010286
  RAX: 0000000000001000 RBX: ffff88859367bff0 RCX: 0000000000000000
  RDX: 0000000000000000 RSI: ffff88859367bfed RDI: 0000000000920907
  RBP: ffffc90035edbe90 R08: 000000000000014b R09: 0000000000000004
  R10: ffff88859367b000 R11: 0000000000000000 R12: 0000000000000ff0
  R13: ffffc90035edbee0 R14: ffff889fb8546180 R15: 0000000000000020
  FS:  00007f80b5f4a740(0000) GS:ffff889fffa00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: ffff88859367c000 CR3: 0000001c170c2001 CR4: 00000000003606e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   iterate_dir+0x122/0x180
   __x64_sys_getdents+0xa6/0x140
   do_syscall_64+0x42/0x100
   entry_SYSCALL_64_after_hwframe+0x44/0xa9

It's in fuse_parse_cache().  %rbx (ffff88859367bff0) is fuse_dirent
pointer - addr + offset.  FUSE_DIRENT_SIZE() is trying to dereference
namelen off of it but that derefs into the next page which is disabled
by pagealloc debug causing a PF.

This is caused by dirent->namelen being accessed before ensuring that
there's enough bytes in the page for the dirent.  Fix it by pushing
down reclen calculation.

Signed-off-by: Tejun Heo 
Fixes: 5d7bc7e8680c ("fuse: allow using readdir cache")
Cc: stable@vger.kernel.org # v4.20+
Signed-off-by: Miklos Szeredi

fuse: unexport fuse_put_request

2019-09-24T13:28:01+00:00

This function has been made static, which now causes a compile-time
warning:

WARNING: "fuse_put_request" [vmlinux] is a static EXPORT_SYMBOL_GPL

Remove the unneeded export.

Fixes: 66abc3599c3c ("fuse: unexport request ops")
Signed-off-by: Arnd Bergmann 
Reviewed-by: Stefan Hajnoczi 
Signed-off-by: Miklos Szeredi

fuse: kmemcg account fs data

2019-09-24T13:28:01+00:00

account per-file, dentry, and inode data

blockdev/superblock and temporary per-request data was left alone, as
this usually isn't accounted

Reviewed-by: Shakeel Butt 
Signed-off-by: Khazhismel Kumykov 
Signed-off-by: Miklos Szeredi

fuse: on 64-bit store time in d_fsdata directly

2019-09-24T13:28:01+00:00

Implements the optimization noted in commit f75fdf22b0a8 ("fuse: don't
use ->d_time"), as the additional memory can be significant.  (In
particular, on SLAB configurations this 8-byte alloc becomes 32 bytes).
Per-dentry, this can consume significant memory.

Reviewed-by: Shakeel Butt 
Signed-off-by: Khazhismel Kumykov 
Signed-off-by: Miklos Szeredi

fuse: fix missing unlock_page in fuse_writepage()

2019-09-24T13:28:01+00:00

unlock_page() was missing in case of an already in-flight write against the
same page.

Signed-off-by: Vasily Averin 
Fixes: ff17be086477 ("fuse: writepage: skip already in flight")
Cc:  # v3.13
Signed-off-by: Miklos Szeredi

virtio-fs: add virtiofs filesystem

2019-09-18T18:17:50+00:00

Add a basic file system module for virtio-fs.  This does not yet contain
shared data support between host and guest or metadata coherency speedups.
However it is already significantly faster than virtio-9p.

Design Overview
===============

With the goal of designing something with better performance and local file
system semantics, a bunch of ideas were proposed.

 - Use fuse protocol (instead of 9p) for communication between guest and
   host.  Guest kernel will be fuse client and a fuse server will run on
   host to serve the requests.

 - For data access inside guest, mmap portion of file in QEMU address space
   and guest accesses this memory using dax.  That way guest page cache is
   bypassed and there is only one copy of data (on host).  This will also
   enable mmap(MAP_SHARED) between guests.

 - For metadata coherency, there is a shared memory region which contains
   version number associated with metadata and any guest changing metadata
   updates version number and other guests refresh metadata on next access.
   This is yet to be implemented.

How virtio-fs differs from existing approaches
==============================================

The unique idea behind virtio-fs is to take advantage of the co-location of
the virtual machine and hypervisor to avoid communication (vmexits).

DAX allows file contents to be accessed without communication with the
hypervisor.  The shared memory region for metadata avoids communication in
the common case where metadata is unchanged.

By replacing expensive communication with cheaper shared memory accesses,
we expect to achieve better performance than approaches based on network
file system protocols.  In addition, this also makes it easier to achieve
local file system semantics (coherency).

These techniques are not applicable to network file system protocols since
the communications channel is bypassed by taking advantage of shared memory
on a local machine.  This is why we decided to build virtio-fs rather than
focus on 9P or NFS.

Caching Modes
=============

Like virtio-9p, different caching modes are supported which determine the
coherency level as well.  The “cache=FOO” and “writeback” options control
the level of coherence between the guest and host filesystems.

 - cache=none
   metadata, data and pathname lookup are not cached in guest.  They are
   always fetched from host and any changes are immediately pushed to host.

 - cache=always
   metadata, data and pathname lookup are cached in guest and never expire.

 - cache=auto
   metadata and pathname lookup cache expires after a configured amount of
   time (default is 1 second).  Data is cached while the file is open
   (close to open consistency).

 - writeback/no_writeback
   These options control the writeback strategy.  If writeback is disabled,
   then normal writes will immediately be synchronized with the host fs.
   If writeback is enabled, then writes may be cached in the guest until
   the file is closed or an fsync(2) performed.  This option has no effect
   on mmap-ed writes or writes going through the DAX mechanism.

Signed-off-by: Stefan Hajnoczi 
Signed-off-by: Vivek Goyal 
Acked-by: Michael S. Tsirkin 
Signed-off-by: Miklos Szeredi

fuse: allow skipping control interface and forced unmount

2019-09-12T12:59:41+00:00

virtio-fs does not support aborting requests which are being
processed. That is requests which have been sent to fuse daemon on host.

Signed-off-by: Vivek Goyal 
Signed-off-by: Miklos Szeredi