VirtualBox hosts can share folders with guests, this commit adds a
VFS driver implementing the Linux-guest side of this, allowing folders
exported by the host to be mounted under Linux.

This driver depends on the guest <-> host IPC functions exported by
the vboxguest driver.

Signed-off-by: Hans de Goede <hdego...@redhat.com>
---
Changes in v17:
- Submit upstream through drivers/staging as this is not getting any
  traction on the fsdevel list
- Add TODO file
- vboxsf_free_inode uses sbi->idr, call rcu_barrier from put_super to make
  sure all delayed rcu free inodes are flushed

Changes in v16:
- Make vboxsf_parse_monolithic() static, reported-by: kbuild test robot

Changes in v15:
- Rebase on top of 5.4-rc1

Changes in v14
- Add a commment explaining possible read cache strategies and which one
  has been chosen
- Change pagecache-invalidation on open (inode_revalidate) to use
  invalidate_inode_pages2() so that mmap-ed pages are dropped from
  the cache too
- Add a comment to vboxsf_file_release explaining why the
  filemap_write_and_wait() call is done there
- Some minor code tweaks

Changes in v13
- Add SPDX tag to Makefile, use foo-y := to set objectfile list
- Drop kerneldoc headers stating the obvious from vfs callbacks,
  to avoid them going stale
- Replace sf_ prefix of functions and data-types with vboxsf_
- Use more normal naming scheme for sbi and private inode data:
    struct vboxsf_sbi *sbi = VBOXSF_SBI(inode->i_sb);
    struct vboxsf_inode *sf_i = VBOXSF_I(inode);
- Refactor directory reading code
- Use goto based unwinding instead of nested if-s in a number of places
- Consolidate dir unlink and rmdir inode_operations into a single function
- Use the page-cache for regular reads/writes too
- Directly set super_operations.free_inode to what used to be our
  vboxsf_i_callback, instead of setting super_operations.destroy_inode
  to a function which just does: call_rcu(&inode->i_rcu, vboxsf_i_callback);
- Use spinlock_irqsafe for ino_idr_lock
  vboxsf_free_inode may be called from a RCU callback, and thus from
  softirq context, so we need to use spinlock_irqsafe vboxsf_new_inode.
  On alloc_inode failure vboxsf_free_inode may be called from process
  context, so it too needs to use spinlock_irqsafe.

Changes in v12:
- Move make_kuid / make_kgid calls to option parsing time and add
  uid_valid / gid_valid checks.
- In init_fs_context call current_uid_gid() to init uid and gid
- Validate dmode, fmode, dmask and fmask options during option parsing
- Use correct types for various mount option variables (kuid_t, kgid_t, umode_t)
- Some small coding-style tweaks

Changes in v11:
- Convert to the new Documentation/filesystems/mount_api.txt mount API
- Fixed all the function kerneldoc comments to have things in the proper order
- Change type of d_type variable passed as type to dir_emit from int to
  unsigned int
- Replaced the fake-ino overflow test with the one suggested by David Howells
- Fixed various coding style issues

See cover-letter for full changelog including older versions
---
 MAINTAINERS                              |   6 +
 drivers/staging/Kconfig                  |   2 +
 drivers/staging/Makefile                 |   1 +
 drivers/staging/vboxsf/Kconfig           |  10 +
 drivers/staging/vboxsf/Makefile          |   5 +
 drivers/staging/vboxsf/TODO              |   7 +
 drivers/staging/vboxsf/dir.c             | 418 +++++++++++
 drivers/staging/vboxsf/file.c            | 370 ++++++++++
 drivers/staging/vboxsf/shfl_hostintf.h   | 901 +++++++++++++++++++++++
 drivers/staging/vboxsf/super.c           | 499 +++++++++++++
 drivers/staging/vboxsf/utils.c           | 550 ++++++++++++++
 drivers/staging/vboxsf/vboxsf_wrappers.c | 371 ++++++++++
 drivers/staging/vboxsf/vfsmod.h          | 138 ++++
 13 files changed, 3278 insertions(+)
 create mode 100644 drivers/staging/vboxsf/Kconfig
 create mode 100644 drivers/staging/vboxsf/Makefile
 create mode 100644 drivers/staging/vboxsf/TODO
 create mode 100644 drivers/staging/vboxsf/dir.c
 create mode 100644 drivers/staging/vboxsf/file.c
 create mode 100644 drivers/staging/vboxsf/shfl_hostintf.h
 create mode 100644 drivers/staging/vboxsf/super.c
 create mode 100644 drivers/staging/vboxsf/utils.c
 create mode 100644 drivers/staging/vboxsf/vboxsf_wrappers.c
 create mode 100644 drivers/staging/vboxsf/vfsmod.h

diff --git a/MAINTAINERS b/MAINTAINERS
index bf03aa6f2856..9637a5385a05 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17362,6 +17362,12 @@ F:     include/linux/vbox_utils.h
 F:     include/uapi/linux/vbox*.h
 F:     drivers/virt/vboxguest/
 
+VIRTUAL BOX SHARED FOLDER VFS DRIVER:
+M:     Hans de Goede <hdego...@redhat.com>
+L:     linux-fsde...@vger.kernel.org
+S:     Maintained
+F:     drivers/staging/vboxsf/*
+
 VIRTUAL SERIO DEVICE DRIVER
 M:     Stephen Chandler Paul <thatsly...@gmail.com>
 S:     Maintained
diff --git a/drivers/staging/Kconfig b/drivers/staging/Kconfig
index a490141a0e88..98f1baf09e70 100644
--- a/drivers/staging/Kconfig
+++ b/drivers/staging/Kconfig
@@ -127,4 +127,6 @@ source "drivers/staging/qlge/Kconfig"
 
 source "drivers/staging/wfx/Kconfig"
 
+source "drivers/staging/vboxsf/Kconfig"
+
 endif # STAGING
diff --git a/drivers/staging/Makefile b/drivers/staging/Makefile
index 4cb548a0ff87..364fd9a5d4da 100644
--- a/drivers/staging/Makefile
+++ b/drivers/staging/Makefile
@@ -54,3 +54,4 @@ obj-$(CONFIG_USB_WUSB)                += wusbcore/
 obj-$(CONFIG_EXFAT_FS)         += exfat/
 obj-$(CONFIG_QLGE)             += qlge/
 obj-$(CONFIG_WFX)              += wfx/
+obj-$(CONFIG_VBOXSF_FS)                += vboxsf/
diff --git a/drivers/staging/vboxsf/Kconfig b/drivers/staging/vboxsf/Kconfig
new file mode 100644
index 000000000000..b84586ae08b3
--- /dev/null
+++ b/drivers/staging/vboxsf/Kconfig
@@ -0,0 +1,10 @@
+config VBOXSF_FS
+       tristate "VirtualBox guest shared folder (vboxsf) support"
+       depends on X86 && VBOXGUEST
+       select NLS
+       help
+         VirtualBox hosts can share folders with guests, this driver
+         implements the Linux-guest side of this allowing folders exported
+         by the host to be mounted under Linux.
+
+         If you want to use shared folders in VirtualBox guests, answer Y or M.
diff --git a/drivers/staging/vboxsf/Makefile b/drivers/staging/vboxsf/Makefile
new file mode 100644
index 000000000000..9e4328e79623
--- /dev/null
+++ b/drivers/staging/vboxsf/Makefile
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: MIT
+
+obj-$(CONFIG_VBOXSF_FS) += vboxsf.o
+
+vboxsf-y := dir.o file.o utils.o vboxsf_wrappers.o super.o
diff --git a/drivers/staging/vboxsf/TODO b/drivers/staging/vboxsf/TODO
new file mode 100644
index 000000000000..8b9193d0d4f0
--- /dev/null
+++ b/drivers/staging/vboxsf/TODO
@@ -0,0 +1,7 @@
+TODO:
+- Find a file-system developer to review this and give their Reviewed-By
+- Address any items coming up during review
+- Move to fs/vboxfs
+
+Please send any patches to Greg Kroah-Hartman <gre...@linuxfoundation.org>
+and Hans de Goede <hdego...@redhat.com>
diff --git a/drivers/staging/vboxsf/dir.c b/drivers/staging/vboxsf/dir.c
new file mode 100644
index 000000000000..f260b5cc1646
--- /dev/null
+++ b/drivers/staging/vboxsf/dir.c
@@ -0,0 +1,418 @@
+// SPDX-License-Identifier: MIT
+/*
+ * VirtualBox Guest Shared Folders support: Directory inode and file operations
+ *
+ * Copyright (C) 2006-2018 Oracle Corporation
+ */
+
+#include <linux/namei.h>
+#include <linux/vbox_utils.h>
+#include "vfsmod.h"
+
+static int vboxsf_dir_open(struct inode *inode, struct file *file)
+{
+       struct vboxsf_sbi *sbi = VBOXSF_SBI(inode->i_sb);
+       struct shfl_createparms params = {};
+       struct vboxsf_dir_info *sf_d;
+       int err;
+
+       sf_d = vboxsf_dir_info_alloc();
+       if (!sf_d)
+               return -ENOMEM;
+
+       params.handle = SHFL_HANDLE_NIL;
+       params.create_flags = SHFL_CF_DIRECTORY | SHFL_CF_ACT_OPEN_IF_EXISTS |
+                             SHFL_CF_ACT_FAIL_IF_NEW | SHFL_CF_ACCESS_READ;
+
+       err = vboxsf_create_at_dentry(file_dentry(file), &params);
+       if (err)
+               goto err_free_dir_info;
+
+       if (params.result != SHFL_FILE_EXISTS) {
+               err = -ENOENT;
+               goto err_close;
+       }
+
+       err = vboxsf_dir_read_all(sbi, sf_d, params.handle);
+       if (err)
+               goto err_close;
+
+       vboxsf_close(sbi->root, params.handle);
+       file->private_data = sf_d;
+       return 0;
+
+err_close:
+       vboxsf_close(sbi->root, params.handle);
+err_free_dir_info:
+       vboxsf_dir_info_free(sf_d);
+       return err;
+}
+
+static int vboxsf_dir_release(struct inode *inode, struct file *file)
+{
+       if (file->private_data)
+               vboxsf_dir_info_free(file->private_data);
+
+       return 0;
+}
+
+static unsigned int vboxsf_get_d_type(u32 mode)
+{
+       unsigned int d_type;
+
+       switch (mode & SHFL_TYPE_MASK) {
+       case SHFL_TYPE_FIFO:
+               d_type = DT_FIFO;
+               break;
+       case SHFL_TYPE_DEV_CHAR:
+               d_type = DT_CHR;
+               break;
+       case SHFL_TYPE_DIRECTORY:
+               d_type = DT_DIR;
+               break;
+       case SHFL_TYPE_DEV_BLOCK:
+               d_type = DT_BLK;
+               break;
+       case SHFL_TYPE_FILE:
+               d_type = DT_REG;
+               break;
+       case SHFL_TYPE_SYMLINK:
+               d_type = DT_LNK;
+               break;
+       case SHFL_TYPE_SOCKET:
+               d_type = DT_SOCK;
+               break;
+       case SHFL_TYPE_WHITEOUT:
+               d_type = DT_WHT;
+               break;
+       default:
+               d_type = DT_UNKNOWN;
+               break;
+       }
+       return d_type;
+}
+
+static bool vboxsf_dir_emit(struct file *dir, struct dir_context *ctx)
+{
+       struct vboxsf_sbi *sbi = VBOXSF_SBI(file_inode(dir)->i_sb);
+       struct vboxsf_dir_info *sf_d = dir->private_data;
+       struct shfl_dirinfo *info;
+       struct vboxsf_dir_buf *b;
+       unsigned int d_type;
+       loff_t i, cur = 0;
+       ino_t fake_ino;
+       size_t size;
+       int err;
+
+       list_for_each_entry(b, &sf_d->info_list, head) {
+try_next_entry:
+               if (ctx->pos >= cur + b->entries) {
+                       cur += b->entries;
+                       continue;
+               }
+
+               /*
+                * Note the vboxsf_dir_info objects we are iterating over here
+                * are variable sized, so the info pointer may end up being
+                * unaligned. This is how we get the data from the host.
+                * Since vboxsf is only supported on x86 machines this is not
+                * a problem.
+                */
+               for (i = 0, info = b->buf; i < ctx->pos - cur; i++) {
+                       size = offsetof(struct shfl_dirinfo, name.string) +
+                              info->name.size;
+                       info = (struct shfl_dirinfo *)((uintptr_t)info + size);
+               }
+
+               /* Info now points to the right entry, emit it. */
+               d_type = vboxsf_get_d_type(info->info.attr.mode);
+
+               /*
+                * On 32 bit systems pos is 64 signed, while ino is 32 bit
+                * unsigned so fake_ino may overflow, check for this.
+                */
+               if ((ino_t)(ctx->pos + 1) != (u64)(ctx->pos + 1)) {
+                       vbg_err("vboxsf: fake ino overflow, truncating dir\n");
+                       return false;
+               }
+               fake_ino = ctx->pos + 1;
+
+               if (sbi->nls) {
+                       char d_name[NAME_MAX];
+
+                       err = vboxsf_nlscpy(sbi, d_name, NAME_MAX,
+                                           info->name.string.utf8,
+                                           info->name.length);
+                       if (err) {
+                               /* skip erroneous entry and proceed */
+                               ctx->pos += 1;
+                               goto try_next_entry;
+                       }
+
+                       return dir_emit(ctx, d_name, strlen(d_name),
+                                       fake_ino, d_type);
+               }
+
+               return dir_emit(ctx, info->name.string.utf8, info->name.length,
+                               fake_ino, d_type);
+       }
+
+       return false;
+}
+
+static int vboxsf_dir_iterate(struct file *dir, struct dir_context *ctx)
+{
+       bool keep_iterating;
+
+       for (keep_iterating = true; keep_iterating; ctx->pos += 1)
+               keep_iterating = vboxsf_dir_emit(dir, ctx);
+
+       return 0;
+}
+
+const struct file_operations vboxsf_dir_fops = {
+       .open = vboxsf_dir_open,
+       .iterate = vboxsf_dir_iterate,
+       .release = vboxsf_dir_release,
+       .read = generic_read_dir,
+       .llseek = generic_file_llseek,
+};
+
+/*
+ * This is called during name resolution/lookup to check if the @dentry in
+ * the cache is still valid. the job is handled by vboxsf_inode_revalidate.
+ */
+static int vboxsf_dentry_revalidate(struct dentry *dentry, unsigned int flags)
+{
+       if (flags & LOOKUP_RCU)
+               return -ECHILD;
+
+       if (d_really_is_positive(dentry))
+               return vboxsf_inode_revalidate(dentry) == 0;
+       else
+               return vboxsf_stat_dentry(dentry, NULL) == -ENOENT;
+}
+
+const struct dentry_operations vboxsf_dentry_ops = {
+       .d_revalidate = vboxsf_dentry_revalidate
+};
+
+/* iops */
+
+static struct dentry *vboxsf_dir_lookup(struct inode *parent,
+                                       struct dentry *dentry,
+                                       unsigned int flags)
+{
+       struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb);
+       struct shfl_fsobjinfo fsinfo;
+       struct inode *inode;
+       int err;
+
+       dentry->d_time = jiffies;
+
+       err = vboxsf_stat_dentry(dentry, &fsinfo);
+       if (err) {
+               inode = (err == -ENOENT) ? NULL : ERR_PTR(err);
+       } else {
+               inode = vboxsf_new_inode(parent->i_sb);
+               if (!IS_ERR(inode))
+                       vboxsf_init_inode(sbi, inode, &fsinfo);
+       }
+
+       return d_splice_alias(inode, dentry);
+}
+
+static int vboxsf_dir_instantiate(struct inode *parent, struct dentry *dentry,
+                                 struct shfl_fsobjinfo *info)
+{
+       struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb);
+       struct vboxsf_inode *sf_i;
+       struct inode *inode;
+
+       inode = vboxsf_new_inode(parent->i_sb);
+       if (IS_ERR(inode))
+               return PTR_ERR(inode);
+
+       sf_i = VBOXSF_I(inode);
+       /* The host may have given us different attr then requested */
+       sf_i->force_restat = 1;
+       vboxsf_init_inode(sbi, inode, info);
+
+       d_instantiate(dentry, inode);
+
+       return 0;
+}
+
+static int vboxsf_dir_create(struct inode *parent, struct dentry *dentry,
+                            umode_t mode, int is_dir)
+{
+       struct vboxsf_inode *sf_parent_i = VBOXSF_I(parent);
+       struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb);
+       struct shfl_createparms params = {};
+       int err;
+
+       params.handle = SHFL_HANDLE_NIL;
+       params.create_flags = SHFL_CF_ACT_CREATE_IF_NEW |
+                             SHFL_CF_ACT_FAIL_IF_EXISTS |
+                             SHFL_CF_ACCESS_READWRITE |
+                             (is_dir ? SHFL_CF_DIRECTORY : 0);
+       params.info.attr.mode = (mode & 0777) |
+                               (is_dir ? SHFL_TYPE_DIRECTORY : SHFL_TYPE_FILE);
+       params.info.attr.additional = SHFLFSOBJATTRADD_NOTHING;
+
+       err = vboxsf_create_at_dentry(dentry, &params);
+       if (err)
+               return err;
+
+       if (params.result != SHFL_FILE_CREATED)
+               return -EPERM;
+
+       vboxsf_close(sbi->root, params.handle);
+
+       err = vboxsf_dir_instantiate(parent, dentry, &params.info);
+       if (err)
+               return err;
+
+       /* parent directory access/change time changed */
+       sf_parent_i->force_restat = 1;
+
+       return 0;
+}
+
+static int vboxsf_dir_mkfile(struct inode *parent, struct dentry *dentry,
+                            umode_t mode, bool excl)
+{
+       return vboxsf_dir_create(parent, dentry, mode, 0);
+}
+
+static int vboxsf_dir_mkdir(struct inode *parent, struct dentry *dentry,
+                           umode_t mode)
+{
+       return vboxsf_dir_create(parent, dentry, mode, 1);
+}
+
+static int vboxsf_dir_unlink(struct inode *parent, struct dentry *dentry)
+{
+       struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb);
+       struct vboxsf_inode *sf_parent_i = VBOXSF_I(parent);
+       struct inode *inode = d_inode(dentry);
+       struct shfl_string *path;
+       u32 flags;
+       int err;
+
+       if (S_ISDIR(inode->i_mode))
+               flags = SHFL_REMOVE_DIR;
+       else
+               flags = SHFL_REMOVE_FILE;
+
+       if (S_ISLNK(inode->i_mode))
+               flags |= SHFL_REMOVE_SYMLINK;
+
+       path = vboxsf_path_from_dentry(sbi, dentry);
+       if (IS_ERR(path))
+               return PTR_ERR(path);
+
+       err = vboxsf_remove(sbi->root, path, flags);
+       __putname(path);
+       if (err)
+               return err;
+
+       /* parent directory access/change time changed */
+       sf_parent_i->force_restat = 1;
+
+       return 0;
+}
+
+static int vboxsf_dir_rename(struct inode *old_parent,
+                            struct dentry *old_dentry,
+                            struct inode *new_parent,
+                            struct dentry *new_dentry,
+                            unsigned int flags)
+{
+       struct vboxsf_sbi *sbi = VBOXSF_SBI(old_parent->i_sb);
+       struct vboxsf_inode *sf_old_parent_i = VBOXSF_I(old_parent);
+       struct vboxsf_inode *sf_new_parent_i = VBOXSF_I(new_parent);
+       u32 shfl_flags = SHFL_RENAME_FILE | SHFL_RENAME_REPLACE_IF_EXISTS;
+       struct shfl_string *old_path, *new_path;
+       int err;
+
+       if (flags)
+               return -EINVAL;
+
+       old_path = vboxsf_path_from_dentry(sbi, old_dentry);
+       if (IS_ERR(old_path))
+               return PTR_ERR(old_path);
+
+       new_path = vboxsf_path_from_dentry(sbi, new_dentry);
+       if (IS_ERR(new_path)) {
+               err = PTR_ERR(new_path);
+               goto err_put_old_path;
+       }
+
+       if (d_inode(old_dentry)->i_mode & S_IFDIR)
+               shfl_flags = 0;
+
+       err = vboxsf_rename(sbi->root, old_path, new_path, shfl_flags);
+       if (err == 0) {
+               /* parent directories access/change time changed */
+               sf_new_parent_i->force_restat = 1;
+               sf_old_parent_i->force_restat = 1;
+       }
+
+       __putname(new_path);
+err_put_old_path:
+       __putname(old_path);
+       return err;
+}
+
+static int vboxsf_dir_symlink(struct inode *parent, struct dentry *dentry,
+                             const char *symname)
+{
+       struct vboxsf_inode *sf_parent_i = VBOXSF_I(parent);
+       struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb);
+       int symname_size = strlen(symname) + 1;
+       struct shfl_string *path, *ssymname;
+       struct shfl_fsobjinfo info;
+       int err;
+
+       path = vboxsf_path_from_dentry(sbi, dentry);
+       if (IS_ERR(path))
+               return PTR_ERR(path);
+
+       ssymname = kmalloc(SHFLSTRING_HEADER_SIZE + symname_size, GFP_KERNEL);
+       if (!ssymname) {
+               __putname(path);
+               return -ENOMEM;
+       }
+       ssymname->length = symname_size - 1;
+       ssymname->size = symname_size;
+       memcpy(ssymname->string.utf8, symname, symname_size);
+
+       err = vboxsf_symlink(sbi->root, path, ssymname, &info);
+       kfree(ssymname);
+       __putname(path);
+       if (err) {
+               /* -EROFS means symlinks are note support -> -EPERM */
+               return (err == -EROFS) ? -EPERM : err;
+       }
+
+       err = vboxsf_dir_instantiate(parent, dentry, &info);
+       if (err)
+               return err;
+
+       /* parent directory access/change time changed */
+       sf_parent_i->force_restat = 1;
+       return 0;
+}
+
+const struct inode_operations vboxsf_dir_iops = {
+       .lookup  = vboxsf_dir_lookup,
+       .create  = vboxsf_dir_mkfile,
+       .mkdir   = vboxsf_dir_mkdir,
+       .rmdir   = vboxsf_dir_unlink,
+       .unlink  = vboxsf_dir_unlink,
+       .rename  = vboxsf_dir_rename,
+       .symlink = vboxsf_dir_symlink,
+       .getattr = vboxsf_getattr,
+       .setattr = vboxsf_setattr,
+};
diff --git a/drivers/staging/vboxsf/file.c b/drivers/staging/vboxsf/file.c
new file mode 100644
index 000000000000..4b61ccf83fca
--- /dev/null
+++ b/drivers/staging/vboxsf/file.c
@@ -0,0 +1,370 @@
+// SPDX-License-Identifier: MIT
+/*
+ * VirtualBox Guest Shared Folders support: Regular file inode and file ops.
+ *
+ * Copyright (C) 2006-2018 Oracle Corporation
+ */
+
+#include <linux/mm.h>
+#include <linux/page-flags.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/sizes.h>
+#include "vfsmod.h"
+
+struct vboxsf_handle {
+       u64 handle;
+       u32 root;
+       u32 access_flags;
+       struct kref refcount;
+       struct list_head head;
+};
+
+static int vboxsf_file_open(struct inode *inode, struct file *file)
+{
+       struct vboxsf_inode *sf_i = VBOXSF_I(inode);
+       struct shfl_createparms params = {};
+       struct vboxsf_handle *sf_handle;
+       u32 access_flags = 0;
+       int err;
+
+       sf_handle = kmalloc(sizeof(*sf_handle), GFP_KERNEL);
+       if (!sf_handle)
+               return -ENOMEM;
+
+       /*
+        * We check the value of params.handle afterwards to find out if
+        * the call succeeded or failed, as the API does not seem to cleanly
+        * distinguish error and informational messages.
+        *
+        * Furthermore, we must set params.handle to SHFL_HANDLE_NIL to
+        * make the shared folders host service use our mode parameter.
+        */
+       params.handle = SHFL_HANDLE_NIL;
+       if (file->f_flags & O_CREAT) {
+               params.create_flags |= SHFL_CF_ACT_CREATE_IF_NEW;
+               /*
+                * We ignore O_EXCL, as the Linux kernel seems to call create
+                * beforehand itself, so O_EXCL should always fail.
+                */
+               if (file->f_flags & O_TRUNC)
+                       params.create_flags |= SHFL_CF_ACT_OVERWRITE_IF_EXISTS;
+               else
+                       params.create_flags |= SHFL_CF_ACT_OPEN_IF_EXISTS;
+       } else {
+               params.create_flags |= SHFL_CF_ACT_FAIL_IF_NEW;
+               if (file->f_flags & O_TRUNC)
+                       params.create_flags |= SHFL_CF_ACT_OVERWRITE_IF_EXISTS;
+       }
+
+       switch (file->f_flags & O_ACCMODE) {
+       case O_RDONLY:
+               access_flags |= SHFL_CF_ACCESS_READ;
+               break;
+
+       case O_WRONLY:
+               access_flags |= SHFL_CF_ACCESS_WRITE;
+               break;
+
+       case O_RDWR:
+               access_flags |= SHFL_CF_ACCESS_READWRITE;
+               break;
+
+       default:
+               WARN_ON(1);
+       }
+
+       if (file->f_flags & O_APPEND)
+               access_flags |= SHFL_CF_ACCESS_APPEND;
+
+       params.create_flags |= access_flags;
+       params.info.attr.mode = inode->i_mode;
+
+       err = vboxsf_create_at_dentry(file_dentry(file), &params);
+       if (err == 0 && params.handle == SHFL_HANDLE_NIL)
+               err = (params.result == SHFL_FILE_EXISTS) ? -EEXIST : -ENOENT;
+       if (err) {
+               kfree(sf_handle);
+               return err;
+       }
+
+       /* the host may have given us different attr then requested */
+       sf_i->force_restat = 1;
+
+       /* init our handle struct and add it to the inode's handles list */
+       sf_handle->handle = params.handle;
+       sf_handle->root = VBOXSF_SBI(inode->i_sb)->root;
+       sf_handle->access_flags = access_flags;
+       kref_init(&sf_handle->refcount);
+
+       mutex_lock(&sf_i->handle_list_mutex);
+       list_add(&sf_handle->head, &sf_i->handle_list);
+       mutex_unlock(&sf_i->handle_list_mutex);
+
+       file->private_data = sf_handle;
+       return 0;
+}
+
+static void vboxsf_handle_release(struct kref *refcount)
+{
+       struct vboxsf_handle *sf_handle =
+               container_of(refcount, struct vboxsf_handle, refcount);
+
+       vboxsf_close(sf_handle->root, sf_handle->handle);
+       kfree(sf_handle);
+}
+
+static int vboxsf_file_release(struct inode *inode, struct file *file)
+{
+       struct vboxsf_inode *sf_i = VBOXSF_I(inode);
+       struct vboxsf_handle *sf_handle = file->private_data;
+
+       /*
+        * When a file is closed on our (the guest) side, we want any subsequent
+        * accesses done on the host side to see all changes done from our side.
+        */
+       filemap_write_and_wait(inode->i_mapping);
+
+       mutex_lock(&sf_i->handle_list_mutex);
+       list_del(&sf_handle->head);
+       mutex_unlock(&sf_i->handle_list_mutex);
+
+       kref_put(&sf_handle->refcount, vboxsf_handle_release);
+       return 0;
+}
+
+/*
+ * Write back dirty pages now, because there may not be any suitable
+ * open files later
+ */
+static void vboxsf_vma_close(struct vm_area_struct *vma)
+{
+       filemap_write_and_wait(vma->vm_file->f_mapping);
+}
+
+static const struct vm_operations_struct vboxsf_file_vm_ops = {
+       .close          = vboxsf_vma_close,
+       .fault          = filemap_fault,
+       .map_pages      = filemap_map_pages,
+};
+
+static int vboxsf_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+       int err;
+
+       err = generic_file_mmap(file, vma);
+       if (!err)
+               vma->vm_ops = &vboxsf_file_vm_ops;
+
+       return err;
+}
+
+/*
+ * Note that since we are accessing files on the host's filesystem, files
+ * may always be changed underneath us by the host!
+ *
+ * The vboxsf API between the guest and the host does not offer any functions
+ * to deal with this. There is no inode-generation to check for changes, no
+ * events / callback on changes and no way to lock files.
+ *
+ * To avoid returning stale data when a file gets *opened* on our (the guest)
+ * side, we do a "stat" on the host side, then compare the mtime with the
+ * last known mtime and invalidate the page-cache if they differ.
+ * This is done from vboxsf_inode_revalidate().
+ *
+ * When reads are done through the read_iter fop, it is possible to do
+ * further cache revalidation then, there are 3 options to deal with this:
+ *
+ * 1)  Rely solely on the revalidation done at open time
+ * 2)  Do another "stat" and compare mtime again. Unfortunately the vboxsf
+ *     host API does not allow stat on handles, so we would need to use
+ *     file->f_path.dentry and the stat will then fail if the file was unlinked
+ *     or renamed (and there is no thing like NFS' silly-rename). So we get:
+ * 2a) "stat" and compare mtime, on stat failure invalidate the cache
+ * 2b) "stat" and compare mtime, on stat failure do nothing
+ * 3)  Simply always call invalidate_inode_pages2_range on the range of the 
read
+ *
+ * Currently we are keeping things KISS and using option 1. this allows
+ * directly using generic_file_read_iter without wrapping it.
+ *
+ * This means that only data written on the host side before open() on
+ * the guest side is guaranteed to be seen by the guest. If necessary
+ * we may provide other read-cache strategies in the future and make this
+ * configurable through a mount option.
+ */
+const struct file_operations vboxsf_reg_fops = {
+       .llseek = generic_file_llseek,
+       .read_iter = generic_file_read_iter,
+       .write_iter = generic_file_write_iter,
+       .mmap = vboxsf_file_mmap,
+       .open = vboxsf_file_open,
+       .release = vboxsf_file_release,
+       .fsync = noop_fsync,
+       .splice_read = generic_file_splice_read,
+};
+
+const struct inode_operations vboxsf_reg_iops = {
+       .getattr = vboxsf_getattr,
+       .setattr = vboxsf_setattr
+};
+
+static int vboxsf_readpage(struct file *file, struct page *page)
+{
+       struct vboxsf_handle *sf_handle = file->private_data;
+       loff_t off = page_offset(page);
+       u32 nread = PAGE_SIZE;
+       u8 *buf;
+       int err;
+
+       buf = kmap(page);
+
+       err = vboxsf_read(sf_handle->root, sf_handle->handle, off, &nread, buf);
+       if (err == 0) {
+               memset(&buf[nread], 0, PAGE_SIZE - nread);
+               flush_dcache_page(page);
+               SetPageUptodate(page);
+       } else {
+               SetPageError(page);
+       }
+
+       kunmap(page);
+       unlock_page(page);
+       return err;
+}
+
+static struct vboxsf_handle *vboxsf_get_write_handle(struct vboxsf_inode *sf_i)
+{
+       struct vboxsf_handle *h, *sf_handle = NULL;
+
+       mutex_lock(&sf_i->handle_list_mutex);
+       list_for_each_entry(h, &sf_i->handle_list, head) {
+               if (h->access_flags == SHFL_CF_ACCESS_WRITE ||
+                   h->access_flags == SHFL_CF_ACCESS_READWRITE) {
+                       kref_get(&h->refcount);
+                       sf_handle = h;
+                       break;
+               }
+       }
+       mutex_unlock(&sf_i->handle_list_mutex);
+
+       return sf_handle;
+}
+
+static int vboxsf_writepage(struct page *page, struct writeback_control *wbc)
+{
+       struct inode *inode = page->mapping->host;
+       struct vboxsf_inode *sf_i = VBOXSF_I(inode);
+       struct vboxsf_handle *sf_handle;
+       loff_t off = page_offset(page);
+       loff_t size = i_size_read(inode);
+       u32 nwrite = PAGE_SIZE;
+       u8 *buf;
+       int err;
+
+       if (off + PAGE_SIZE > size)
+               nwrite = size & ~PAGE_MASK;
+
+       sf_handle = vboxsf_get_write_handle(sf_i);
+       if (!sf_handle)
+               return -EBADF;
+
+       buf = kmap(page);
+       err = vboxsf_write(sf_handle->root, sf_handle->handle,
+                          off, &nwrite, buf);
+       kunmap(page);
+
+       kref_put(&sf_handle->refcount, vboxsf_handle_release);
+
+       if (err == 0) {
+               ClearPageError(page);
+               /* mtime changed */
+               sf_i->force_restat = 1;
+       } else {
+               ClearPageUptodate(page);
+       }
+
+       unlock_page(page);
+       return err;
+}
+
+static int vboxsf_write_end(struct file *file, struct address_space *mapping,
+                           loff_t pos, unsigned int len, unsigned int copied,
+                           struct page *page, void *fsdata)
+{
+       struct inode *inode = mapping->host;
+       struct vboxsf_handle *sf_handle = file->private_data;
+       unsigned int from = pos & ~PAGE_MASK;
+       u32 nwritten = len;
+       u8 *buf;
+       int err;
+
+       buf = kmap(page);
+       err = vboxsf_write(sf_handle->root, sf_handle->handle,
+                          pos, &nwritten, buf + from);
+       kunmap(page);
+
+       if (err) {
+               nwritten = 0;
+               goto out;
+       }
+
+       /* mtime changed */
+       VBOXSF_I(inode)->force_restat = 1;
+
+       if (!PageUptodate(page) && nwritten == PAGE_SIZE)
+               SetPageUptodate(page);
+
+       pos += nwritten;
+       if (pos > inode->i_size)
+               i_size_write(inode, pos);
+
+out:
+       unlock_page(page);
+       put_page(page);
+
+       return nwritten;
+}
+
+const struct address_space_operations vboxsf_reg_aops = {
+       .readpage = vboxsf_readpage,
+       .writepage = vboxsf_writepage,
+       .set_page_dirty = __set_page_dirty_nobuffers,
+       .write_begin = simple_write_begin,
+       .write_end = vboxsf_write_end,
+};
+
+static const char *vboxsf_get_link(struct dentry *dentry, struct inode *inode,
+                                  struct delayed_call *done)
+{
+       struct vboxsf_sbi *sbi = VBOXSF_SBI(inode->i_sb);
+       struct shfl_string *path;
+       char *link;
+       int err;
+
+       if (!dentry)
+               return ERR_PTR(-ECHILD);
+
+       path = vboxsf_path_from_dentry(sbi, dentry);
+       if (IS_ERR(path))
+               return (char *)path;
+
+       link = kzalloc(PATH_MAX, GFP_KERNEL);
+       if (!link) {
+               __putname(path);
+               return ERR_PTR(-ENOMEM);
+       }
+
+       err = vboxsf_readlink(sbi->root, path, PATH_MAX, link);
+       __putname(path);
+       if (err) {
+               kfree(link);
+               return ERR_PTR(err);
+       }
+
+       set_delayed_call(done, kfree_link, link);
+       return link;
+}
+
+const struct inode_operations vboxsf_lnk_iops = {
+       .get_link = vboxsf_get_link
+};
diff --git a/drivers/staging/vboxsf/shfl_hostintf.h 
b/drivers/staging/vboxsf/shfl_hostintf.h
new file mode 100644
index 000000000000..aca829062c12
--- /dev/null
+++ b/drivers/staging/vboxsf/shfl_hostintf.h
@@ -0,0 +1,901 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * VirtualBox Shared Folders: host interface definition.
+ *
+ * Copyright (C) 2006-2018 Oracle Corporation
+ */
+
+#ifndef SHFL_HOSTINTF_H
+#define SHFL_HOSTINTF_H
+
+#include <linux/vbox_vmmdev_types.h>
+
+/* The max in/out buffer size for a FN_READ or FN_WRITE call */
+#define SHFL_MAX_RW_COUNT           (16 * SZ_1M)
+
+/*
+ * Structures shared between guest and the service
+ * can be relocated and use offsets to point to variable
+ * length parts.
+ *
+ * Shared folders protocol works with handles.
+ * Before doing any action on a file system object,
+ * one have to obtain the object handle via a SHFL_FN_CREATE
+ * request. A handle must be closed with SHFL_FN_CLOSE.
+ */
+
+enum {
+       SHFL_FN_QUERY_MAPPINGS = 1,     /* Query mappings changes. */
+       SHFL_FN_QUERY_MAP_NAME = 2,     /* Query map name. */
+       SHFL_FN_CREATE = 3,             /* Open/create object. */
+       SHFL_FN_CLOSE = 4,              /* Close object handle. */
+       SHFL_FN_READ = 5,               /* Read object content. */
+       SHFL_FN_WRITE = 6,              /* Write new object content. */
+       SHFL_FN_LOCK = 7,               /* Lock/unlock a range in the object. */
+       SHFL_FN_LIST = 8,               /* List object content. */
+       SHFL_FN_INFORMATION = 9,        /* Query/set object information. */
+       /* Note function number 10 is not used! */
+       SHFL_FN_REMOVE = 11,            /* Remove object */
+       SHFL_FN_MAP_FOLDER_OLD = 12,    /* Map folder (legacy) */
+       SHFL_FN_UNMAP_FOLDER = 13,      /* Unmap folder */
+       SHFL_FN_RENAME = 14,            /* Rename object */
+       SHFL_FN_FLUSH = 15,             /* Flush file */
+       SHFL_FN_SET_UTF8 = 16,          /* Select UTF8 filename encoding */
+       SHFL_FN_MAP_FOLDER = 17,        /* Map folder */
+       SHFL_FN_READLINK = 18,          /* Read symlink dest (as of VBox 4.0) */
+       SHFL_FN_SYMLINK = 19,           /* Create symlink (as of VBox 4.0) */
+       SHFL_FN_SET_SYMLINKS = 20,      /* Ask host to show symlinks (4.0+) */
+};
+
+/* Root handles for a mapping are of type u32, Root handles are unique. */
+#define SHFL_ROOT_NIL          UINT_MAX
+
+/* Shared folders handle for an opened object are of type u64. */
+#define SHFL_HANDLE_NIL                ULLONG_MAX
+
+/* Hardcoded maximum length (in chars) of a shared folder name. */
+#define SHFL_MAX_LEN         (256)
+/* Hardcoded maximum number of shared folder mapping available to the guest. */
+#define SHFL_MAX_MAPPINGS    (64)
+
+/** Shared folder string buffer structure. */
+struct shfl_string {
+       /** Allocated size of the string member in bytes. */
+       u16 size;
+
+       /** Length of string without trailing nul in bytes. */
+       u16 length;
+
+       /** UTF-8 or UTF-16 string. Nul terminated. */
+       union {
+               u8 utf8[2];
+               u16 utf16[1];
+               u16 ucs2[1]; /* misnomer, use utf16. */
+       } string;
+};
+VMMDEV_ASSERT_SIZE(shfl_string, 6);
+
+/* The size of shfl_string w/o the string part. */
+#define SHFLSTRING_HEADER_SIZE  4
+
+/* Calculate size of the string. */
+static inline u32 shfl_string_buf_size(const struct shfl_string *string)
+{
+       return string ? SHFLSTRING_HEADER_SIZE + string->size : 0;
+}
+
+/* Set user id on execution (S_ISUID). */
+#define SHFL_UNIX_ISUID             0004000U
+/* Set group id on execution (S_ISGID). */
+#define SHFL_UNIX_ISGID             0002000U
+/* Sticky bit (S_ISVTX / S_ISTXT). */
+#define SHFL_UNIX_ISTXT             0001000U
+
+/* Owner readable (S_IRUSR). */
+#define SHFL_UNIX_IRUSR             0000400U
+/* Owner writable (S_IWUSR). */
+#define SHFL_UNIX_IWUSR             0000200U
+/* Owner executable (S_IXUSR). */
+#define SHFL_UNIX_IXUSR             0000100U
+
+/* Group readable (S_IRGRP). */
+#define SHFL_UNIX_IRGRP             0000040U
+/* Group writable (S_IWGRP). */
+#define SHFL_UNIX_IWGRP             0000020U
+/* Group executable (S_IXGRP). */
+#define SHFL_UNIX_IXGRP             0000010U
+
+/* Other readable (S_IROTH). */
+#define SHFL_UNIX_IROTH             0000004U
+/* Other writable (S_IWOTH). */
+#define SHFL_UNIX_IWOTH             0000002U
+/* Other executable (S_IXOTH). */
+#define SHFL_UNIX_IXOTH             0000001U
+
+/* Named pipe (fifo) (S_IFIFO). */
+#define SHFL_TYPE_FIFO              0010000U
+/* Character device (S_IFCHR). */
+#define SHFL_TYPE_DEV_CHAR          0020000U
+/* Directory (S_IFDIR). */
+#define SHFL_TYPE_DIRECTORY         0040000U
+/* Block device (S_IFBLK). */
+#define SHFL_TYPE_DEV_BLOCK         0060000U
+/* Regular file (S_IFREG). */
+#define SHFL_TYPE_FILE              0100000U
+/* Symbolic link (S_IFLNK). */
+#define SHFL_TYPE_SYMLINK           0120000U
+/* Socket (S_IFSOCK). */
+#define SHFL_TYPE_SOCKET            0140000U
+/* Whiteout (S_IFWHT). */
+#define SHFL_TYPE_WHITEOUT          0160000U
+/* Type mask (S_IFMT). */
+#define SHFL_TYPE_MASK              0170000U
+
+/* Checks the mode flags indicate a directory (S_ISDIR). */
+#define SHFL_IS_DIRECTORY(m)   (((m) & SHFL_TYPE_MASK) == SHFL_TYPE_DIRECTORY)
+/* Checks the mode flags indicate a symbolic link (S_ISLNK). */
+#define SHFL_IS_SYMLINK(m)     (((m) & SHFL_TYPE_MASK) == SHFL_TYPE_SYMLINK)
+
+/** The available additional information in a shfl_fsobjattr object. */
+enum shfl_fsobjattr_add {
+       /** No additional information is available / requested. */
+       SHFLFSOBJATTRADD_NOTHING = 1,
+       /**
+        * The additional unix attributes (shfl_fsobjattr::u::unix_attr) are
+        *  available / requested.
+        */
+       SHFLFSOBJATTRADD_UNIX,
+       /**
+        * The additional extended attribute size (shfl_fsobjattr::u::size) is
+        *  available / requested.
+        */
+       SHFLFSOBJATTRADD_EASIZE,
+       /**
+        * The last valid item (inclusive).
+        * The valid range is SHFLFSOBJATTRADD_NOTHING thru
+        * SHFLFSOBJATTRADD_LAST.
+        */
+       SHFLFSOBJATTRADD_LAST = SHFLFSOBJATTRADD_EASIZE,
+
+       /** The usual 32-bit hack. */
+       SHFLFSOBJATTRADD_32BIT_SIZE_HACK = 0x7fffffff
+};
+
+/**
+ * Additional unix Attributes, these are available when
+ * shfl_fsobjattr.additional == SHFLFSOBJATTRADD_UNIX.
+ */
+struct shfl_fsobjattr_unix {
+       /**
+        * The user owning the filesystem object (st_uid).
+        * This field is ~0U if not supported.
+        */
+       u32 uid;
+
+       /**
+        * The group the filesystem object is assigned (st_gid).
+        * This field is ~0U if not supported.
+        */
+       u32 gid;
+
+       /**
+        * Number of hard links to this filesystem object (st_nlink).
+        * This field is 1 if the filesystem doesn't support hardlinking or
+        * the information isn't available.
+        */
+       u32 hardlinks;
+
+       /**
+        * The device number of the device which this filesystem object resides
+        * on (st_dev). This field is 0 if this information is not available.
+        */
+       u32 inode_id_device;
+
+       /**
+        * The unique identifier (within the filesystem) of this filesystem
+        * object (st_ino). Together with inode_id_device, this field can be
+        * used as a OS wide unique id, when both their values are not 0.
+        * This field is 0 if the information is not available.
+        */
+       u64 inode_id;
+
+       /**
+        * User flags (st_flags).
+        * This field is 0 if this information is not available.
+        */
+       u32 flags;
+
+       /**
+        * The current generation number (st_gen).
+        * This field is 0 if this information is not available.
+        */
+       u32 generation_id;
+
+       /**
+        * The device number of a char. or block device type object (st_rdev).
+        * This field is 0 if the file isn't a char. or block device or when
+        * the OS doesn't use the major+minor device idenfication scheme.
+        */
+       u32 device;
+} __packed;
+
+/** Extended attribute size. */
+struct shfl_fsobjattr_easize {
+       /** Size of EAs. */
+       s64 cb;
+} __packed;
+
+/** Shared folder filesystem object attributes. */
+struct shfl_fsobjattr {
+       /** Mode flags (st_mode). SHFL_UNIX_*, SHFL_TYPE_*, and SHFL_DOS_*. */
+       u32 mode;
+
+       /** The additional attributes available. */
+       enum shfl_fsobjattr_add additional;
+
+       /**
+        * Additional attributes.
+        *
+        * Unless explicitly specified to an API, the API can provide additional
+        * data as it is provided by the underlying OS.
+        */
+       union {
+               struct shfl_fsobjattr_unix unix_attr;
+               struct shfl_fsobjattr_easize size;
+       } __packed u;
+} __packed;
+VMMDEV_ASSERT_SIZE(shfl_fsobjattr, 44);
+
+struct shfl_timespec {
+       s64 ns_relative_to_unix_epoch;
+};
+
+/** Filesystem object information structure. */
+struct shfl_fsobjinfo {
+       /**
+        * Logical size (st_size).
+        * For normal files this is the size of the file.
+        * For symbolic links, this is the length of the path name contained
+        * in the symbolic link.
+        * For other objects this fields needs to be specified.
+        */
+       s64 size;
+
+       /** Disk allocation size (st_blocks * DEV_BSIZE). */
+       s64 allocated;
+
+       /** Time of last access (st_atime). */
+       struct shfl_timespec access_time;
+
+       /** Time of last data modification (st_mtime). */
+       struct shfl_timespec modification_time;
+
+       /**
+        * Time of last status change (st_ctime).
+        * If not available this is set to modification_time.
+        */
+       struct shfl_timespec change_time;
+
+       /**
+        * Time of file birth (st_birthtime).
+        * If not available this is set to change_time.
+        */
+       struct shfl_timespec birth_time;
+
+       /** Attributes. */
+       struct shfl_fsobjattr attr;
+
+} __packed;
+VMMDEV_ASSERT_SIZE(shfl_fsobjinfo, 92);
+
+/**
+ * result of an open/create request.
+ * Along with handle value the result code
+ * identifies what has happened while
+ * trying to open the object.
+ */
+enum shfl_create_result {
+       SHFL_NO_RESULT,
+       /** Specified path does not exist. */
+       SHFL_PATH_NOT_FOUND,
+       /** Path to file exists, but the last component does not. */
+       SHFL_FILE_NOT_FOUND,
+       /** File already exists and either has been opened or not. */
+       SHFL_FILE_EXISTS,
+       /** New file was created. */
+       SHFL_FILE_CREATED,
+       /** Existing file was replaced or overwritten. */
+       SHFL_FILE_REPLACED
+};
+
+/* No flags. Initialization value. */
+#define SHFL_CF_NONE                  (0x00000000)
+
+/*
+ * Only lookup the object, do not return a handle. When this is set all other
+ * flags are ignored.
+ */
+#define SHFL_CF_LOOKUP                (0x00000001)
+
+/*
+ * Open parent directory of specified object.
+ * Useful for the corresponding Windows FSD flag
+ * and for opening paths like \\dir\\*.* to search the 'dir'.
+ */
+#define SHFL_CF_OPEN_TARGET_DIRECTORY (0x00000002)
+
+/* Create/open a directory. */
+#define SHFL_CF_DIRECTORY             (0x00000004)
+
+/*
+ *  Open/create action to do if object exists
+ *  and if the object does not exists.
+ *  REPLACE file means atomically DELETE and CREATE.
+ *  OVERWRITE file means truncating the file to 0 and
+ *  setting new size.
+ *  When opening an existing directory REPLACE and OVERWRITE
+ *  actions are considered invalid, and cause returning
+ *  FILE_EXISTS with NIL handle.
+ */
+#define SHFL_CF_ACT_MASK_IF_EXISTS      (0x000000f0)
+#define SHFL_CF_ACT_MASK_IF_NEW         (0x00000f00)
+
+/* What to do if object exists. */
+#define SHFL_CF_ACT_OPEN_IF_EXISTS      (0x00000000)
+#define SHFL_CF_ACT_FAIL_IF_EXISTS      (0x00000010)
+#define SHFL_CF_ACT_REPLACE_IF_EXISTS   (0x00000020)
+#define SHFL_CF_ACT_OVERWRITE_IF_EXISTS (0x00000030)
+
+/* What to do if object does not exist. */
+#define SHFL_CF_ACT_CREATE_IF_NEW       (0x00000000)
+#define SHFL_CF_ACT_FAIL_IF_NEW         (0x00000100)
+
+/* Read/write requested access for the object. */
+#define SHFL_CF_ACCESS_MASK_RW          (0x00003000)
+
+/* No access requested. */
+#define SHFL_CF_ACCESS_NONE             (0x00000000)
+/* Read access requested. */
+#define SHFL_CF_ACCESS_READ             (0x00001000)
+/* Write access requested. */
+#define SHFL_CF_ACCESS_WRITE            (0x00002000)
+/* Read/Write access requested. */
+#define SHFL_CF_ACCESS_READWRITE       (0x00003000)
+
+/* Requested share access for the object. */
+#define SHFL_CF_ACCESS_MASK_DENY        (0x0000c000)
+
+/* Allow any access. */
+#define SHFL_CF_ACCESS_DENYNONE         (0x00000000)
+/* Do not allow read. */
+#define SHFL_CF_ACCESS_DENYREAD         (0x00004000)
+/* Do not allow write. */
+#define SHFL_CF_ACCESS_DENYWRITE        (0x00008000)
+/* Do not allow access. */
+#define SHFL_CF_ACCESS_DENYALL          (0x0000c000)
+
+/* Requested access to attributes of the object. */
+#define SHFL_CF_ACCESS_MASK_ATTR        (0x00030000)
+
+/* No access requested. */
+#define SHFL_CF_ACCESS_ATTR_NONE        (0x00000000)
+/* Read access requested. */
+#define SHFL_CF_ACCESS_ATTR_READ        (0x00010000)
+/* Write access requested. */
+#define SHFL_CF_ACCESS_ATTR_WRITE       (0x00020000)
+/* Read/Write access requested. */
+#define SHFL_CF_ACCESS_ATTR_READWRITE   (0x00030000)
+
+/*
+ * The file is opened in append mode.
+ * Ignored if SHFL_CF_ACCESS_WRITE is not set.
+ */
+#define SHFL_CF_ACCESS_APPEND           (0x00040000)
+
+/** Create parameters buffer struct for SHFL_FN_CREATE call */
+struct shfl_createparms {
+       /** Returned handle of opened object. */
+       u64 handle;
+
+       /** Returned result of the operation */
+       enum shfl_create_result result;
+
+       /** SHFL_CF_* */
+       u32 create_flags;
+
+       /**
+        * Attributes of object to create and
+        * returned actual attributes of opened/created object.
+        */
+       struct shfl_fsobjinfo info;
+} __packed;
+
+/** Shared Folder directory information */
+struct shfl_dirinfo {
+       /** Full information about the object. */
+       struct shfl_fsobjinfo info;
+       /**
+        * The length of the short field (number of UTF16 chars).
+        * It is 16-bit for reasons of alignment.
+        */
+       u16 short_name_len;
+       /**
+        * The short name for 8.3 compatibility.
+        * Empty string if not available.
+        */
+       u16 short_name[14];
+       struct shfl_string name;
+};
+
+/** Shared folder filesystem properties. */
+struct shfl_fsproperties {
+       /**
+        * The maximum size of a filesystem object name.
+        * This does not include the '\\0'.
+        */
+       u32 max_component_len;
+
+       /**
+        * True if the filesystem is remote.
+        * False if the filesystem is local.
+        */
+       bool remote;
+
+       /**
+        * True if the filesystem is case sensitive.
+        * False if the filesystem is case insensitive.
+        */
+       bool case_sensitive;
+
+       /**
+        * True if the filesystem is mounted read only.
+        * False if the filesystem is mounted read write.
+        */
+       bool read_only;
+
+       /**
+        * True if the filesystem can encode unicode object names.
+        * False if it can't.
+        */
+       bool supports_unicode;
+
+       /**
+        * True if the filesystem is compresses.
+        * False if it isn't or we don't know.
+        */
+       bool compressed;
+
+       /**
+        * True if the filesystem compresses of individual files.
+        * False if it doesn't or we don't know.
+        */
+       bool file_compression;
+};
+VMMDEV_ASSERT_SIZE(shfl_fsproperties, 12);
+
+struct shfl_volinfo {
+       s64 total_allocation_bytes;
+       s64 available_allocation_bytes;
+       u32 bytes_per_allocation_unit;
+       u32 bytes_per_sector;
+       u32 serial;
+       struct shfl_fsproperties properties;
+};
+
+
+/** SHFL_FN_MAP_FOLDER Parameters structure. */
+struct shfl_map_folder {
+       /**
+        * pointer, in:
+        * Points to struct shfl_string buffer.
+        */
+       struct vmmdev_hgcm_function_parameter path;
+
+       /**
+        * pointer, out: SHFLROOT (u32)
+        * Root handle of the mapping which name is queried.
+        */
+       struct vmmdev_hgcm_function_parameter root;
+
+       /**
+        * pointer, in: UTF16
+        * Path delimiter
+        */
+       struct vmmdev_hgcm_function_parameter delimiter;
+
+       /**
+        * pointer, in: SHFLROOT (u32)
+        * Case senstive flag
+        */
+       struct vmmdev_hgcm_function_parameter case_sensitive;
+
+};
+
+/* Number of parameters */
+#define SHFL_CPARMS_MAP_FOLDER (4)
+
+
+/** SHFL_FN_UNMAP_FOLDER Parameters structure. */
+struct shfl_unmap_folder {
+       /**
+        * pointer, in: SHFLROOT (u32)
+        * Root handle of the mapping which name is queried.
+        */
+       struct vmmdev_hgcm_function_parameter root;
+
+};
+
+/* Number of parameters */
+#define SHFL_CPARMS_UNMAP_FOLDER (1)
+
+
+/** SHFL_FN_CREATE Parameters structure. */
+struct shfl_create {
+       /**
+        * pointer, in: SHFLROOT (u32)
+        * Root handle of the mapping which name is queried.
+        */
+       struct vmmdev_hgcm_function_parameter root;
+
+       /**
+        * pointer, in:
+        * Points to struct shfl_string buffer.
+        */
+       struct vmmdev_hgcm_function_parameter path;
+
+       /**
+        * pointer, in/out:
+        * Points to struct shfl_createparms buffer.
+        */
+       struct vmmdev_hgcm_function_parameter parms;
+
+};
+
+/* Number of parameters */
+#define SHFL_CPARMS_CREATE (3)
+
+
+/** SHFL_FN_CLOSE Parameters structure. */
+struct shfl_close {
+       /**
+        * pointer, in: SHFLROOT (u32)
+        * Root handle of the mapping which name is queried.
+        */
+       struct vmmdev_hgcm_function_parameter root;
+
+       /**
+        * value64, in:
+        * SHFLHANDLE (u64) of object to close.
+        */
+       struct vmmdev_hgcm_function_parameter handle;
+
+};
+
+/* Number of parameters */
+#define SHFL_CPARMS_CLOSE (2)
+
+
+/** SHFL_FN_READ Parameters structure. */
+struct shfl_read {
+       /**
+        * pointer, in: SHFLROOT (u32)
+        * Root handle of the mapping which name is queried.
+        */
+       struct vmmdev_hgcm_function_parameter root;
+
+       /**
+        * value64, in:
+        * SHFLHANDLE (u64) of object to read from.
+        */
+       struct vmmdev_hgcm_function_parameter handle;
+
+       /**
+        * value64, in:
+        * Offset to read from.
+        */
+       struct vmmdev_hgcm_function_parameter offset;
+
+       /**
+        * value64, in/out:
+        * Bytes to read/How many were read.
+        */
+       struct vmmdev_hgcm_function_parameter cb;
+
+       /**
+        * pointer, out:
+        * Buffer to place data to.
+        */
+       struct vmmdev_hgcm_function_parameter buffer;
+
+};
+
+/* Number of parameters */
+#define SHFL_CPARMS_READ (5)
+
+
+/** SHFL_FN_WRITE Parameters structure. */
+struct shfl_write {
+       /**
+        * pointer, in: SHFLROOT (u32)
+        * Root handle of the mapping which name is queried.
+        */
+       struct vmmdev_hgcm_function_parameter root;
+
+       /**
+        * value64, in:
+        * SHFLHANDLE (u64) of object to write to.
+        */
+       struct vmmdev_hgcm_function_parameter handle;
+
+       /**
+        * value64, in:
+        * Offset to write to.
+        */
+       struct vmmdev_hgcm_function_parameter offset;
+
+       /**
+        * value64, in/out:
+        * Bytes to write/How many were written.
+        */
+       struct vmmdev_hgcm_function_parameter cb;
+
+       /**
+        * pointer, in:
+        * Data to write.
+        */
+       struct vmmdev_hgcm_function_parameter buffer;
+
+};
+
+/* Number of parameters */
+#define SHFL_CPARMS_WRITE (5)
+
+
+/*
+ * SHFL_FN_LIST
+ * Listing information includes variable length RTDIRENTRY[EX] structures.
+ */
+
+#define SHFL_LIST_NONE                 0
+#define SHFL_LIST_RETURN_ONE           1
+
+/** SHFL_FN_LIST Parameters structure. */
+struct shfl_list {
+       /**
+        * pointer, in: SHFLROOT (u32)
+        * Root handle of the mapping which name is queried.
+        */
+       struct vmmdev_hgcm_function_parameter root;
+
+       /**
+        * value64, in:
+        * SHFLHANDLE (u64) of object to be listed.
+        */
+       struct vmmdev_hgcm_function_parameter handle;
+
+       /**
+        * value32, in:
+        * List flags SHFL_LIST_*.
+        */
+       struct vmmdev_hgcm_function_parameter flags;
+
+       /**
+        * value32, in/out:
+        * Bytes to be used for listing information/How many bytes were used.
+        */
+       struct vmmdev_hgcm_function_parameter cb;
+
+       /**
+        * pointer, in/optional
+        * Points to struct shfl_string buffer that specifies a search path.
+        */
+       struct vmmdev_hgcm_function_parameter path;
+
+       /**
+        * pointer, out:
+        * Buffer to place listing information to. (struct shfl_dirinfo)
+        */
+       struct vmmdev_hgcm_function_parameter buffer;
+
+       /**
+        * value32, in/out:
+        * Indicates a key where the listing must be resumed.
+        * in: 0 means start from begin of object.
+        * out: 0 means listing completed.
+        */
+       struct vmmdev_hgcm_function_parameter resume_point;
+
+       /**
+        * pointer, out:
+        * Number of files returned
+        */
+       struct vmmdev_hgcm_function_parameter file_count;
+};
+
+/* Number of parameters */
+#define SHFL_CPARMS_LIST (8)
+
+
+/** SHFL_FN_READLINK Parameters structure. */
+struct shfl_readLink {
+       /**
+        * pointer, in: SHFLROOT (u32)
+        * Root handle of the mapping which name is queried.
+        */
+       struct vmmdev_hgcm_function_parameter root;
+
+       /**
+        * pointer, in:
+        * Points to struct shfl_string buffer.
+        */
+       struct vmmdev_hgcm_function_parameter path;
+
+       /**
+        * pointer, out:
+        * Buffer to place data to.
+        */
+       struct vmmdev_hgcm_function_parameter buffer;
+
+};
+
+/* Number of parameters */
+#define SHFL_CPARMS_READLINK (3)
+
+
+/* SHFL_FN_INFORMATION */
+
+/* Mask of Set/Get bit. */
+#define SHFL_INFO_MODE_MASK    (0x1)
+/* Get information */
+#define SHFL_INFO_GET          (0x0)
+/* Set information */
+#define SHFL_INFO_SET          (0x1)
+
+/* Get name of the object. */
+#define SHFL_INFO_NAME         (0x2)
+/* Set size of object (extend/trucate); only applies to file objects */
+#define SHFL_INFO_SIZE         (0x4)
+/* Get/Set file object info. */
+#define SHFL_INFO_FILE         (0x8)
+/* Get volume information. */
+#define SHFL_INFO_VOLUME       (0x10)
+
+/** SHFL_FN_INFORMATION Parameters structure. */
+struct shfl_information {
+       /**
+        * pointer, in: SHFLROOT (u32)
+        * Root handle of the mapping which name is queried.
+        */
+       struct vmmdev_hgcm_function_parameter root;
+
+       /**
+        * value64, in:
+        * SHFLHANDLE (u64) of object to be listed.
+        */
+       struct vmmdev_hgcm_function_parameter handle;
+
+       /**
+        * value32, in:
+        * SHFL_INFO_*
+        */
+       struct vmmdev_hgcm_function_parameter flags;
+
+       /**
+        * value32, in/out:
+        * Bytes to be used for information/How many bytes were used.
+        */
+       struct vmmdev_hgcm_function_parameter cb;
+
+       /**
+        * pointer, in/out:
+        * Information to be set/get (shfl_fsobjinfo or shfl_string). Do not
+        * forget to set the shfl_fsobjinfo::attr::additional for a get
+        * operation as well.
+        */
+       struct vmmdev_hgcm_function_parameter info;
+
+};
+
+/* Number of parameters */
+#define SHFL_CPARMS_INFORMATION (5)
+
+
+/* SHFL_FN_REMOVE */
+
+#define SHFL_REMOVE_FILE        (0x1)
+#define SHFL_REMOVE_DIR         (0x2)
+#define SHFL_REMOVE_SYMLINK     (0x4)
+
+/** SHFL_FN_REMOVE Parameters structure. */
+struct shfl_remove {
+       /**
+        * pointer, in: SHFLROOT (u32)
+        * Root handle of the mapping which name is queried.
+        */
+       struct vmmdev_hgcm_function_parameter root;
+
+       /**
+        * pointer, in:
+        * Points to struct shfl_string buffer.
+        */
+       struct vmmdev_hgcm_function_parameter path;
+
+       /**
+        * value32, in:
+        * remove flags (file/directory)
+        */
+       struct vmmdev_hgcm_function_parameter flags;
+
+};
+
+#define SHFL_CPARMS_REMOVE  (3)
+
+
+/* SHFL_FN_RENAME */
+
+#define SHFL_RENAME_FILE                (0x1)
+#define SHFL_RENAME_DIR                 (0x2)
+#define SHFL_RENAME_REPLACE_IF_EXISTS   (0x4)
+
+/** SHFL_FN_RENAME Parameters structure. */
+struct shfl_rename {
+       /**
+        * pointer, in: SHFLROOT (u32)
+        * Root handle of the mapping which name is queried.
+        */
+       struct vmmdev_hgcm_function_parameter root;
+
+       /**
+        * pointer, in:
+        * Points to struct shfl_string src.
+        */
+       struct vmmdev_hgcm_function_parameter src;
+
+       /**
+        * pointer, in:
+        * Points to struct shfl_string dest.
+        */
+       struct vmmdev_hgcm_function_parameter dest;
+
+       /**
+        * value32, in:
+        * rename flags (file/directory)
+        */
+       struct vmmdev_hgcm_function_parameter flags;
+
+};
+
+#define SHFL_CPARMS_RENAME  (4)
+
+
+/** SHFL_FN_SYMLINK Parameters structure. */
+struct shfl_symlink {
+       /**
+        * pointer, in: SHFLROOT (u32)
+        * Root handle of the mapping which name is queried.
+        */
+       struct vmmdev_hgcm_function_parameter root;
+
+       /**
+        * pointer, in:
+        * Points to struct shfl_string of path for the new symlink.
+        */
+       struct vmmdev_hgcm_function_parameter new_path;
+
+       /**
+        * pointer, in:
+        * Points to struct shfl_string of destination for symlink.
+        */
+       struct vmmdev_hgcm_function_parameter old_path;
+
+       /**
+        * pointer, out:
+        * Information about created symlink.
+        */
+       struct vmmdev_hgcm_function_parameter info;
+
+};
+
+#define SHFL_CPARMS_SYMLINK  (4)
+
+#endif
diff --git a/drivers/staging/vboxsf/super.c b/drivers/staging/vboxsf/super.c
new file mode 100644
index 000000000000..3913ffafa83b
--- /dev/null
+++ b/drivers/staging/vboxsf/super.c
@@ -0,0 +1,499 @@
+// SPDX-License-Identifier: MIT
+/*
+ * VirtualBox Guest Shared Folders support: Virtual File System.
+ *
+ * Module initialization/finalization
+ * File system registration/deregistration
+ * Superblock reading
+ * Few utility functions
+ *
+ * Copyright (C) 2006-2018 Oracle Corporation
+ */
+
+#include <linux/idr.h>
+#include <linux/fs_parser.h>
+#include <linux/magic.h>
+#include <linux/module.h>
+#include <linux/nls.h>
+#include <linux/statfs.h>
+#include <linux/vbox_utils.h>
+#include "vfsmod.h"
+
+#define VBOXSF_SUPER_MAGIC 0x786f4256 /* 'VBox' little endian */
+
+#define VBSF_MOUNT_SIGNATURE_BYTE_0 ('\000')
+#define VBSF_MOUNT_SIGNATURE_BYTE_1 ('\377')
+#define VBSF_MOUNT_SIGNATURE_BYTE_2 ('\376')
+#define VBSF_MOUNT_SIGNATURE_BYTE_3 ('\375')
+
+static int follow_symlinks;
+module_param(follow_symlinks, int, 0444);
+MODULE_PARM_DESC(follow_symlinks,
+                "Let host resolve symlinks rather than showing them");
+
+static DEFINE_IDA(vboxsf_bdi_ida);
+static DEFINE_MUTEX(vboxsf_setup_mutex);
+static bool vboxsf_setup_done;
+static struct super_operations vboxsf_super_ops; /* forward declaration */
+static struct kmem_cache *vboxsf_inode_cachep;
+
+static char * const vboxsf_default_nls = CONFIG_NLS_DEFAULT;
+
+enum  { opt_nls, opt_uid, opt_gid, opt_ttl, opt_dmode, opt_fmode,
+       opt_dmask, opt_fmask };
+
+static const struct fs_parameter_spec vboxsf_param_specs[] = {
+       fsparam_string  ("nls",         opt_nls),
+       fsparam_u32     ("uid",         opt_uid),
+       fsparam_u32     ("gid",         opt_gid),
+       fsparam_u32     ("ttl",         opt_ttl),
+       fsparam_u32oct  ("dmode",       opt_dmode),
+       fsparam_u32oct  ("fmode",       opt_fmode),
+       fsparam_u32oct  ("dmask",       opt_dmask),
+       fsparam_u32oct  ("fmask",       opt_fmask),
+       {}
+};
+
+static const struct fs_parameter_description vboxsf_fs_parameters = {
+       .name  = "vboxsf",
+       .specs  = vboxsf_param_specs,
+};
+
+static int vboxsf_parse_param(struct fs_context *fc, struct fs_parameter 
*param)
+{
+       struct vboxsf_fs_context *ctx = fc->fs_private;
+       struct fs_parse_result result;
+       kuid_t uid;
+       kgid_t gid;
+       int opt;
+
+       opt = fs_parse(fc, &vboxsf_fs_parameters, param, &result);
+       if (opt < 0)
+               return opt;
+
+       switch (opt) {
+       case opt_nls:
+               if (fc->purpose != FS_CONTEXT_FOR_MOUNT) {
+                       vbg_err("vboxsf: Cannot reconfigure nls option\n");
+                       return -EINVAL;
+               }
+               ctx->nls_name = param->string;
+               param->string = NULL;
+               break;
+       case opt_uid:
+               uid = make_kuid(current_user_ns(), result.uint_32);
+               if (!uid_valid(uid))
+                       return -EINVAL;
+               ctx->o.uid = uid;
+               break;
+       case opt_gid:
+               gid = make_kgid(current_user_ns(), result.uint_32);
+               if (!gid_valid(gid))
+                       return -EINVAL;
+               ctx->o.gid = gid;
+               break;
+       case opt_ttl:
+               ctx->o.ttl = msecs_to_jiffies(result.uint_32);
+               break;
+       case opt_dmode:
+               if (result.uint_32 & ~0777)
+                       return -EINVAL;
+               ctx->o.dmode = result.uint_32;
+               ctx->o.dmode_set = true;
+               break;
+       case opt_fmode:
+               if (result.uint_32 & ~0777)
+                       return -EINVAL;
+               ctx->o.fmode = result.uint_32;
+               ctx->o.fmode_set = true;
+               break;
+       case opt_dmask:
+               if (result.uint_32 & ~07777)
+                       return -EINVAL;
+               ctx->o.dmask = result.uint_32;
+               break;
+       case opt_fmask:
+               if (result.uint_32 & ~07777)
+                       return -EINVAL;
+               ctx->o.fmask = result.uint_32;
+               break;
+       default:
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
+static int vboxsf_fill_super(struct super_block *sb, struct fs_context *fc)
+{
+       struct vboxsf_fs_context *ctx = fc->fs_private;
+       struct shfl_string *folder_name, root_path;
+       struct vboxsf_sbi *sbi;
+       struct dentry *droot;
+       struct inode *iroot;
+       char *nls_name;
+       size_t size;
+       int err;
+
+       if (!fc->source)
+               return -EINVAL;
+
+       sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
+       if (!sbi)
+               return -ENOMEM;
+
+       sbi->o = ctx->o;
+       idr_init(&sbi->ino_idr);
+       spin_lock_init(&sbi->ino_idr_lock);
+       sbi->next_generation = 1;
+       sbi->bdi_id = -1;
+
+       /* Load nls if not utf8 */
+       nls_name = ctx->nls_name ? ctx->nls_name : vboxsf_default_nls;
+       if (strcmp(nls_name, "utf8") != 0) {
+               if (nls_name == vboxsf_default_nls)
+                       sbi->nls = load_nls_default();
+               else
+                       sbi->nls = load_nls(nls_name);
+
+               if (!sbi->nls) {
+                       vbg_err("vboxsf: Count not load '%s' nls\n", nls_name);
+                       err = -EINVAL;
+                       goto fail_free;
+               }
+       }
+
+       sbi->bdi_id = ida_simple_get(&vboxsf_bdi_ida, 0, 0, GFP_KERNEL);
+       if (sbi->bdi_id < 0) {
+               err = sbi->bdi_id;
+               goto fail_free;
+       }
+
+       err = super_setup_bdi_name(sb, "vboxsf-%s.%d", fc->source, sbi->bdi_id);
+       if (err)
+               goto fail_free;
+
+       /* Turn source into a shfl_string and map the folder */
+       size = strlen(fc->source) + 1;
+       folder_name = kmalloc(SHFLSTRING_HEADER_SIZE + size, GFP_KERNEL);
+       if (!folder_name)
+               goto fail_free;
+       folder_name->size = size;
+       folder_name->length = size - 1;
+       strlcpy(folder_name->string.utf8, fc->source, size);
+       err = vboxsf_map_folder(folder_name, &sbi->root);
+       kfree(folder_name);
+       if (err) {
+               vbg_err("vboxsf: Host rejected mount of '%s' with error %d\n",
+                       fc->source, err);
+               goto fail_free;
+       }
+
+       root_path.length = 1;
+       root_path.size = 2;
+       root_path.string.utf8[0] = '/';
+       root_path.string.utf8[1] = 0;
+       err = vboxsf_stat(sbi, &root_path, &sbi->root_info);
+       if (err)
+               goto fail_unmap;
+
+       sb->s_magic = VBOXSF_SUPER_MAGIC;
+       sb->s_blocksize = 1024;
+       sb->s_maxbytes = MAX_LFS_FILESIZE;
+       sb->s_op = &vboxsf_super_ops;
+       sb->s_d_op = &vboxsf_dentry_ops;
+
+       iroot = iget_locked(sb, 0);
+       if (!iroot) {
+               err = -ENOMEM;
+               goto fail_unmap;
+       }
+       vboxsf_init_inode(sbi, iroot, &sbi->root_info);
+       unlock_new_inode(iroot);
+
+       droot = d_make_root(iroot);
+       if (!droot) {
+               err = -ENOMEM;
+               goto fail_unmap;
+       }
+
+       sb->s_root = droot;
+       sb->s_fs_info = sbi;
+       return 0;
+
+fail_unmap:
+       vboxsf_unmap_folder(sbi->root);
+fail_free:
+       if (sbi->bdi_id >= 0)
+               ida_simple_remove(&vboxsf_bdi_ida, sbi->bdi_id);
+       if (sbi->nls)
+               unload_nls(sbi->nls);
+       idr_destroy(&sbi->ino_idr);
+       kfree(sbi);
+       return err;
+}
+
+static void vboxsf_inode_init_once(void *data)
+{
+       struct vboxsf_inode *sf_i = data;
+
+       mutex_init(&sf_i->handle_list_mutex);
+       inode_init_once(&sf_i->vfs_inode);
+}
+
+static struct inode *vboxsf_alloc_inode(struct super_block *sb)
+{
+       struct vboxsf_inode *sf_i;
+
+       sf_i = kmem_cache_alloc(vboxsf_inode_cachep, GFP_NOFS);
+       if (!sf_i)
+               return NULL;
+
+       sf_i->force_restat = 0;
+       INIT_LIST_HEAD(&sf_i->handle_list);
+
+       return &sf_i->vfs_inode;
+}
+
+static void vboxsf_free_inode(struct inode *inode)
+{
+       struct vboxsf_sbi *sbi = VBOXSF_SBI(inode->i_sb);
+       unsigned long flags;
+
+       spin_lock_irqsave(&sbi->ino_idr_lock, flags);
+       idr_remove(&sbi->ino_idr, inode->i_ino);
+       spin_unlock_irqrestore(&sbi->ino_idr_lock, flags);
+       kmem_cache_free(vboxsf_inode_cachep, VBOXSF_I(inode));
+}
+
+static void vboxsf_put_super(struct super_block *sb)
+{
+       struct vboxsf_sbi *sbi = VBOXSF_SBI(sb);
+
+       vboxsf_unmap_folder(sbi->root);
+       if (sbi->bdi_id >= 0)
+               ida_simple_remove(&vboxsf_bdi_ida, sbi->bdi_id);
+       if (sbi->nls)
+               unload_nls(sbi->nls);
+
+       /*
+        * vboxsf_free_inode uses the idr, make sure all delayed rcu free
+        * inodes are flushed.
+        */
+       rcu_barrier();
+       idr_destroy(&sbi->ino_idr);
+       kfree(sbi);
+}
+
+static int vboxsf_statfs(struct dentry *dentry, struct kstatfs *stat)
+{
+       struct super_block *sb = dentry->d_sb;
+       struct shfl_volinfo shfl_volinfo;
+       struct vboxsf_sbi *sbi;
+       u32 buf_len;
+       int err;
+
+       sbi = VBOXSF_SBI(sb);
+       buf_len = sizeof(shfl_volinfo);
+       err = vboxsf_fsinfo(sbi->root, 0, SHFL_INFO_GET | SHFL_INFO_VOLUME,
+                           &buf_len, &shfl_volinfo);
+       if (err)
+               return err;
+
+       stat->f_type = VBOXSF_SUPER_MAGIC;
+       stat->f_bsize = shfl_volinfo.bytes_per_allocation_unit;
+
+       do_div(shfl_volinfo.total_allocation_bytes,
+              shfl_volinfo.bytes_per_allocation_unit);
+       stat->f_blocks = shfl_volinfo.total_allocation_bytes;
+
+       do_div(shfl_volinfo.available_allocation_bytes,
+              shfl_volinfo.bytes_per_allocation_unit);
+       stat->f_bfree  = shfl_volinfo.available_allocation_bytes;
+       stat->f_bavail = shfl_volinfo.available_allocation_bytes;
+
+       stat->f_files = 1000;
+       /*
+        * Don't return 0 here since the guest may then think that it is not
+        * possible to create any more files.
+        */
+       stat->f_ffree = 1000000;
+       stat->f_fsid.val[0] = 0;
+       stat->f_fsid.val[1] = 0;
+       stat->f_namelen = 255;
+       return 0;
+}
+
+static struct super_operations vboxsf_super_ops = {
+       .alloc_inode    = vboxsf_alloc_inode,
+       .free_inode     = vboxsf_free_inode,
+       .put_super      = vboxsf_put_super,
+       .statfs         = vboxsf_statfs,
+};
+
+static int vboxsf_setup(void)
+{
+       int err;
+
+       mutex_lock(&vboxsf_setup_mutex);
+
+       if (vboxsf_setup_done)
+               goto success;
+
+       vboxsf_inode_cachep =
+               kmem_cache_create("vboxsf_inode_cache",
+                                 sizeof(struct vboxsf_inode), 0,
+                                 (SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD |
+                                  SLAB_ACCOUNT),
+                                 vboxsf_inode_init_once);
+       if (!vboxsf_inode_cachep) {
+               err = -ENOMEM;
+               goto fail_nomem;
+       }
+
+       err = vboxsf_connect();
+       if (err) {
+               vbg_err("vboxsf: err %d connecting to guest PCI-device\n", err);
+               vbg_err("vboxsf: make sure you are inside a VirtualBox VM\n");
+               vbg_err("vboxsf: and check dmesg for vboxguest errors\n");
+               goto fail_free_cache;
+       }
+
+       err = vboxsf_set_utf8();
+       if (err) {
+               vbg_err("vboxsf_setutf8 error %d\n", err);
+               goto fail_disconnect;
+       }
+
+       if (!follow_symlinks) {
+               err = vboxsf_set_symlinks();
+               if (err)
+                       vbg_warn("vboxsf: Unable to show symlinks: %d\n", err);
+       }
+
+       vboxsf_setup_done = true;
+success:
+       mutex_unlock(&vboxsf_setup_mutex);
+       return 0;
+
+fail_disconnect:
+       vboxsf_disconnect();
+fail_free_cache:
+       kmem_cache_destroy(vboxsf_inode_cachep);
+fail_nomem:
+       mutex_unlock(&vboxsf_setup_mutex);
+       return err;
+}
+
+static int vboxsf_parse_monolithic(struct fs_context *fc, void *data)
+{
+       char *options = data;
+
+       if (options && options[0] == VBSF_MOUNT_SIGNATURE_BYTE_0 &&
+                      options[1] == VBSF_MOUNT_SIGNATURE_BYTE_1 &&
+                      options[2] == VBSF_MOUNT_SIGNATURE_BYTE_2 &&
+                      options[3] == VBSF_MOUNT_SIGNATURE_BYTE_3) {
+               vbg_err("vboxsf: Old binary mount data not supported, remove 
obsolete mount.vboxsf and/or update your VBoxService.\n");
+               return -EINVAL;
+       }
+
+       return generic_parse_monolithic(fc, data);
+}
+
+static int vboxsf_get_tree(struct fs_context *fc)
+{
+       int err;
+
+       err = vboxsf_setup();
+       if (err)
+               return err;
+
+       return vfs_get_super(fc, vfs_get_independent_super, vboxsf_fill_super);
+}
+
+static int vboxsf_reconfigure(struct fs_context *fc)
+{
+       struct vboxsf_sbi *sbi = VBOXSF_SBI(fc->root->d_sb);
+       struct vboxsf_fs_context *ctx = fc->fs_private;
+       struct inode *iroot;
+
+       iroot = ilookup(fc->root->d_sb, 0);
+       if (!iroot)
+               return -ENOENT;
+
+       /* Apply changed options to the root inode */
+       sbi->o = ctx->o;
+       vboxsf_init_inode(sbi, iroot, &sbi->root_info);
+
+       return 0;
+}
+
+static void vboxsf_free_fc(struct fs_context *fc)
+{
+       struct vboxsf_fs_context *ctx = fc->fs_private;
+
+       kfree(ctx->nls_name);
+       kfree(ctx);
+}
+
+static const struct fs_context_operations vboxsf_context_ops = {
+       .free                   = vboxsf_free_fc,
+       .parse_param            = vboxsf_parse_param,
+       .parse_monolithic       = vboxsf_parse_monolithic,
+       .get_tree               = vboxsf_get_tree,
+       .reconfigure            = vboxsf_reconfigure,
+};
+
+static int vboxsf_init_fs_context(struct fs_context *fc)
+{
+       struct vboxsf_fs_context *ctx;
+
+       ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+       if (!ctx)
+               return -ENOMEM;
+
+       current_uid_gid(&ctx->o.uid, &ctx->o.gid);
+
+       fc->fs_private = ctx;
+       fc->ops = &vboxsf_context_ops;
+       return 0;
+}
+
+static struct file_system_type vboxsf_fs_type = {
+       .owner                  = THIS_MODULE,
+       .name                   = "vboxsf",
+       .init_fs_context        = vboxsf_init_fs_context,
+       .parameters             = &vboxsf_fs_parameters,
+       .kill_sb                = kill_anon_super
+};
+
+/* Module initialization/finalization handlers */
+static int __init vboxsf_init(void)
+{
+       return register_filesystem(&vboxsf_fs_type);
+}
+
+static void __exit vboxsf_fini(void)
+{
+       unregister_filesystem(&vboxsf_fs_type);
+
+       mutex_lock(&vboxsf_setup_mutex);
+       if (vboxsf_setup_done) {
+               vboxsf_disconnect();
+               /*
+                * Make sure all delayed rcu free inodes are flushed
+                * before we destroy the cache.
+                */
+               rcu_barrier();
+               kmem_cache_destroy(vboxsf_inode_cachep);
+       }
+       mutex_unlock(&vboxsf_setup_mutex);
+}
+
+module_init(vboxsf_init);
+module_exit(vboxsf_fini);
+
+MODULE_DESCRIPTION("Oracle VM VirtualBox Module for Host File System Access");
+MODULE_AUTHOR("Oracle Corporation");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS_FS("vboxsf");
diff --git a/drivers/staging/vboxsf/utils.c b/drivers/staging/vboxsf/utils.c
new file mode 100644
index 000000000000..1870b69c824e
--- /dev/null
+++ b/drivers/staging/vboxsf/utils.c
@@ -0,0 +1,550 @@
+// SPDX-License-Identifier: MIT
+/*
+ * VirtualBox Guest Shared Folders support: Utility functions.
+ * Mainly conversion from/to VirtualBox/Linux data structures.
+ *
+ * Copyright (C) 2006-2018 Oracle Corporation
+ */
+
+#include <linux/namei.h>
+#include <linux/nls.h>
+#include <linux/sizes.h>
+#include <linux/vfs.h>
+#include "vfsmod.h"
+
+struct inode *vboxsf_new_inode(struct super_block *sb)
+{
+       struct vboxsf_sbi *sbi = VBOXSF_SBI(sb);
+       struct inode *inode;
+       unsigned long flags;
+       int cursor, ret;
+       u32 gen;
+
+       inode = new_inode(sb);
+       if (!inode)
+               return ERR_PTR(-ENOMEM);
+
+       idr_preload(GFP_KERNEL);
+       spin_lock_irqsave(&sbi->ino_idr_lock, flags);
+       cursor = idr_get_cursor(&sbi->ino_idr);
+       ret = idr_alloc_cyclic(&sbi->ino_idr, inode, 1, 0, GFP_ATOMIC);
+       if (ret >= 0 && ret < cursor)
+               sbi->next_generation++;
+       gen = sbi->next_generation;
+       spin_unlock_irqrestore(&sbi->ino_idr_lock, flags);
+       idr_preload_end();
+
+       if (ret < 0) {
+               iput(inode);
+               return ERR_PTR(ret);
+       }
+
+       inode->i_ino = ret;
+       inode->i_generation = gen;
+       return inode;
+}
+
+/* set [inode] attributes based on [info], uid/gid based on [sbi] */
+void vboxsf_init_inode(struct vboxsf_sbi *sbi, struct inode *inode,
+                      const struct shfl_fsobjinfo *info)
+{
+       const struct shfl_fsobjattr *attr;
+       s64 allocated;
+       int mode;
+
+       attr = &info->attr;
+
+#define mode_set(r) ((attr->mode & (SHFL_UNIX_##r)) ? (S_##r) : 0)
+
+       mode = mode_set(IRUSR);
+       mode |= mode_set(IWUSR);
+       mode |= mode_set(IXUSR);
+
+       mode |= mode_set(IRGRP);
+       mode |= mode_set(IWGRP);
+       mode |= mode_set(IXGRP);
+
+       mode |= mode_set(IROTH);
+       mode |= mode_set(IWOTH);
+       mode |= mode_set(IXOTH);
+
+#undef mode_set
+
+       /* We use the host-side values for these */
+       inode->i_flags |= S_NOATIME | S_NOCMTIME;
+       inode->i_mapping->a_ops = &vboxsf_reg_aops;
+
+       if (SHFL_IS_DIRECTORY(attr->mode)) {
+               inode->i_mode = sbi->o.dmode_set ? sbi->o.dmode : mode;
+               inode->i_mode &= ~sbi->o.dmask;
+               inode->i_mode |= S_IFDIR;
+               inode->i_op = &vboxsf_dir_iops;
+               inode->i_fop = &vboxsf_dir_fops;
+               /*
+                * XXX: this probably should be set to the number of entries
+                * in the directory plus two (. ..)
+                */
+               set_nlink(inode, 1);
+       } else if (SHFL_IS_SYMLINK(attr->mode)) {
+               inode->i_mode = sbi->o.fmode_set ? sbi->o.fmode : mode;
+               inode->i_mode &= ~sbi->o.fmask;
+               inode->i_mode |= S_IFLNK;
+               inode->i_op = &vboxsf_lnk_iops;
+               set_nlink(inode, 1);
+       } else {
+               inode->i_mode = sbi->o.fmode_set ? sbi->o.fmode : mode;
+               inode->i_mode &= ~sbi->o.fmask;
+               inode->i_mode |= S_IFREG;
+               inode->i_op = &vboxsf_reg_iops;
+               inode->i_fop = &vboxsf_reg_fops;
+               set_nlink(inode, 1);
+       }
+
+       inode->i_uid = sbi->o.uid;
+       inode->i_gid = sbi->o.gid;
+
+       inode->i_size = info->size;
+       inode->i_blkbits = 12;
+       /* i_blocks always in units of 512 bytes! */
+       allocated = info->allocated + 511;
+       do_div(allocated, 512);
+       inode->i_blocks = allocated;
+
+       inode->i_atime = ns_to_timespec64(
+                                info->access_time.ns_relative_to_unix_epoch);
+       inode->i_ctime = ns_to_timespec64(
+                                info->change_time.ns_relative_to_unix_epoch);
+       inode->i_mtime = ns_to_timespec64(
+                          info->modification_time.ns_relative_to_unix_epoch);
+}
+
+int vboxsf_create_at_dentry(struct dentry *dentry,
+                           struct shfl_createparms *params)
+{
+       struct vboxsf_sbi *sbi = VBOXSF_SBI(dentry->d_sb);
+       struct shfl_string *path;
+       int err;
+
+       path = vboxsf_path_from_dentry(sbi, dentry);
+       if (IS_ERR(path))
+               return PTR_ERR(path);
+
+       err = vboxsf_create(sbi->root, path, params);
+       __putname(path);
+
+       return err;
+}
+
+int vboxsf_stat(struct vboxsf_sbi *sbi, struct shfl_string *path,
+               struct shfl_fsobjinfo *info)
+{
+       struct shfl_createparms params = {};
+       int err;
+
+       params.handle = SHFL_HANDLE_NIL;
+       params.create_flags = SHFL_CF_LOOKUP | SHFL_CF_ACT_FAIL_IF_NEW;
+
+       err = vboxsf_create(sbi->root, path, &params);
+       if (err)
+               return err;
+
+       if (params.result != SHFL_FILE_EXISTS)
+               return -ENOENT;
+
+       if (info)
+               *info = params.info;
+
+       return 0;
+}
+
+int vboxsf_stat_dentry(struct dentry *dentry, struct shfl_fsobjinfo *info)
+{
+       struct vboxsf_sbi *sbi = VBOXSF_SBI(dentry->d_sb);
+       struct shfl_string *path;
+       int err;
+
+       path = vboxsf_path_from_dentry(sbi, dentry);
+       if (IS_ERR(path))
+               return PTR_ERR(path);
+
+       err = vboxsf_stat(sbi, path, info);
+       __putname(path);
+       return err;
+}
+
+int vboxsf_inode_revalidate(struct dentry *dentry)
+{
+       struct vboxsf_sbi *sbi = VBOXSF_SBI(dentry->d_sb);
+       struct vboxsf_inode *sf_i;
+       struct shfl_fsobjinfo info;
+       struct timespec64 prev_mtime;
+       struct inode *inode;
+       int err;
+
+       if (!dentry || !d_really_is_positive(dentry))
+               return -EINVAL;
+
+       inode = d_inode(dentry);
+       prev_mtime = inode->i_mtime;
+       sf_i = VBOXSF_I(inode);
+       if (!sf_i->force_restat) {
+               if (time_before(jiffies, dentry->d_time + sbi->o.ttl))
+                       return 0;
+       }
+
+       err = vboxsf_stat_dentry(dentry, &info);
+       if (err)
+               return err;
+
+       dentry->d_time = jiffies;
+       sf_i->force_restat = 0;
+       vboxsf_init_inode(sbi, inode, &info);
+
+       /*
+        * If the file was changed on the host side we need to invalidate the
+        * page-cache for it.  Note this also gets triggered by our own writes,
+        * this is unavoidable.
+        */
+       if (timespec64_compare(&inode->i_mtime, &prev_mtime) > 0)
+               invalidate_inode_pages2(inode->i_mapping);
+
+       return 0;
+}
+
+int vboxsf_getattr(const struct path *path, struct kstat *kstat,
+                  u32 request_mask, unsigned int flags)
+{
+       int err;
+       struct dentry *dentry = path->dentry;
+       struct inode *inode = d_inode(dentry);
+       struct vboxsf_inode *sf_i = VBOXSF_I(inode);
+
+       switch (flags & AT_STATX_SYNC_TYPE) {
+       case AT_STATX_DONT_SYNC:
+               err = 0;
+               break;
+       case AT_STATX_FORCE_SYNC:
+               sf_i->force_restat = 1;
+               /* fall-through */
+       default:
+               err = vboxsf_inode_revalidate(dentry);
+       }
+       if (err)
+               return err;
+
+       generic_fillattr(d_inode(dentry), kstat);
+       return 0;
+}
+
+int vboxsf_setattr(struct dentry *dentry, struct iattr *iattr)
+{
+       struct vboxsf_inode *sf_i = VBOXSF_I(d_inode(dentry));
+       struct vboxsf_sbi *sbi = VBOXSF_SBI(dentry->d_sb);
+       struct shfl_createparms params = {};
+       struct shfl_fsobjinfo info = {};
+       u32 buf_len;
+       int err;
+
+       params.handle = SHFL_HANDLE_NIL;
+       params.create_flags = SHFL_CF_ACT_OPEN_IF_EXISTS |
+                             SHFL_CF_ACT_FAIL_IF_NEW |
+                             SHFL_CF_ACCESS_ATTR_WRITE;
+
+       /* this is at least required for Posix hosts */
+       if (iattr->ia_valid & ATTR_SIZE)
+               params.create_flags |= SHFL_CF_ACCESS_WRITE;
+
+       err = vboxsf_create_at_dentry(dentry, &params);
+       if (err || params.result != SHFL_FILE_EXISTS)
+               return err ? err : -ENOENT;
+
+#define mode_set(r) ((iattr->ia_mode & (S_##r)) ? SHFL_UNIX_##r : 0)
+
+       /*
+        * Setting the file size and setting the other attributes has to
+        * be handled separately.
+        */
+       if (iattr->ia_valid & (ATTR_MODE | ATTR_ATIME | ATTR_MTIME)) {
+               if (iattr->ia_valid & ATTR_MODE) {
+                       info.attr.mode = mode_set(IRUSR);
+                       info.attr.mode |= mode_set(IWUSR);
+                       info.attr.mode |= mode_set(IXUSR);
+                       info.attr.mode |= mode_set(IRGRP);
+                       info.attr.mode |= mode_set(IWGRP);
+                       info.attr.mode |= mode_set(IXGRP);
+                       info.attr.mode |= mode_set(IROTH);
+                       info.attr.mode |= mode_set(IWOTH);
+                       info.attr.mode |= mode_set(IXOTH);
+
+                       if (iattr->ia_mode & S_IFDIR)
+                               info.attr.mode |= SHFL_TYPE_DIRECTORY;
+                       else
+                               info.attr.mode |= SHFL_TYPE_FILE;
+               }
+
+               if (iattr->ia_valid & ATTR_ATIME)
+                       info.access_time.ns_relative_to_unix_epoch =
+                                           timespec64_to_ns(&iattr->ia_atime);
+
+               if (iattr->ia_valid & ATTR_MTIME)
+                       info.modification_time.ns_relative_to_unix_epoch =
+                                           timespec64_to_ns(&iattr->ia_mtime);
+
+               /*
+                * Ignore ctime (inode change time) as it can't be set
+                * from userland anyway.
+                */
+
+               buf_len = sizeof(info);
+               err = vboxsf_fsinfo(sbi->root, params.handle,
+                                   SHFL_INFO_SET | SHFL_INFO_FILE, &buf_len,
+                                   &info);
+               if (err) {
+                       vboxsf_close(sbi->root, params.handle);
+                       return err;
+               }
+
+               /* the host may have given us different attr then requested */
+               sf_i->force_restat = 1;
+       }
+
+#undef mode_set
+
+       if (iattr->ia_valid & ATTR_SIZE) {
+               memset(&info, 0, sizeof(info));
+               info.size = iattr->ia_size;
+               buf_len = sizeof(info);
+               err = vboxsf_fsinfo(sbi->root, params.handle,
+                                   SHFL_INFO_SET | SHFL_INFO_SIZE, &buf_len,
+                                   &info);
+               if (err) {
+                       vboxsf_close(sbi->root, params.handle);
+                       return err;
+               }
+
+               /* the host may have given us different attr then requested */
+               sf_i->force_restat = 1;
+       }
+
+       vboxsf_close(sbi->root, params.handle);
+
+       /* Update the inode with what the host has actually given us. */
+       if (sf_i->force_restat)
+               vboxsf_inode_revalidate(dentry);
+
+       return 0;
+}
+
+/*
+ * [dentry] contains string encoded in coding system that corresponds
+ * to [sbi]->nls, we must convert it to UTF8 here.
+ * Returns a shfl_string allocated through __getname (must be freed using
+ * __putname), or an ERR_PTR on error.
+ */
+struct shfl_string *vboxsf_path_from_dentry(struct vboxsf_sbi *sbi,
+                                           struct dentry *dentry)
+{
+       struct shfl_string *shfl_path;
+       int path_len, out_len, nb;
+       char *buf, *path;
+       wchar_t uni;
+       u8 *out;
+
+       buf = __getname();
+       if (!buf)
+               return ERR_PTR(-ENOMEM);
+
+       path = dentry_path_raw(dentry, buf, PATH_MAX);
+       if (IS_ERR(path)) {
+               __putname(buf);
+               return (struct shfl_string *)path;
+       }
+       path_len = strlen(path);
+
+       if (sbi->nls) {
+               shfl_path = __getname();
+               if (!shfl_path) {
+                       __putname(buf);
+                       return ERR_PTR(-ENOMEM);
+               }
+
+               out = shfl_path->string.utf8;
+               out_len = PATH_MAX - SHFLSTRING_HEADER_SIZE - 1;
+
+               while (path_len) {
+                       nb = sbi->nls->char2uni(path, path_len, &uni);
+                       if (nb < 0) {
+                               __putname(shfl_path);
+                               __putname(buf);
+                               return ERR_PTR(-EINVAL);
+                       }
+                       path += nb;
+                       path_len -= nb;
+
+                       nb = utf32_to_utf8(uni, out, out_len);
+                       if (nb < 0) {
+                               __putname(shfl_path);
+                               __putname(buf);
+                               return ERR_PTR(-ENAMETOOLONG);
+                       }
+                       out += nb;
+                       out_len -= nb;
+               }
+               *out = 0;
+               shfl_path->length = out - shfl_path->string.utf8;
+               shfl_path->size = shfl_path->length + 1;
+               __putname(buf);
+       } else {
+               if ((SHFLSTRING_HEADER_SIZE + path_len + 1) > PATH_MAX) {
+                       __putname(buf);
+                       return ERR_PTR(-ENAMETOOLONG);
+               }
+               /*
+                * dentry_path stores the name at the end of buf, but the
+                * shfl_string string we return must be properly aligned.
+                */
+               shfl_path = (struct shfl_string *)buf;
+               memmove(shfl_path->string.utf8, path, path_len);
+               shfl_path->string.utf8[path_len] = 0;
+               shfl_path->length = path_len;
+               shfl_path->size = path_len + 1;
+       }
+
+       return shfl_path;
+}
+
+int vboxsf_nlscpy(struct vboxsf_sbi *sbi, char *name, size_t name_bound_len,
+                 const unsigned char *utf8_name, size_t utf8_len)
+{
+       const char *in;
+       char *out;
+       size_t out_len;
+       size_t out_bound_len;
+       size_t in_bound_len;
+
+       in = utf8_name;
+       in_bound_len = utf8_len;
+
+       out = name;
+       out_len = 0;
+       /* Reserve space for terminating 0 */
+       out_bound_len = name_bound_len - 1;
+
+       while (in_bound_len) {
+               int nb;
+               unicode_t uni;
+
+               nb = utf8_to_utf32(in, in_bound_len, &uni);
+               if (nb < 0)
+                       return -EINVAL;
+
+               in += nb;
+               in_bound_len -= nb;
+
+               nb = sbi->nls->uni2char(uni, out, out_bound_len);
+               if (nb < 0)
+                       return nb;
+
+               out += nb;
+               out_bound_len -= nb;
+               out_len += nb;
+       }
+
+       *out = 0;
+
+       return 0;
+}
+
+static struct vboxsf_dir_buf *vboxsf_dir_buf_alloc(struct list_head *list)
+{
+       struct vboxsf_dir_buf *b;
+
+       b = kmalloc(sizeof(*b), GFP_KERNEL);
+       if (!b)
+               return NULL;
+
+       b->buf = kmalloc(DIR_BUFFER_SIZE, GFP_KERNEL);
+       if (!b->buf) {
+               kfree(b);
+               return NULL;
+       }
+
+       b->entries = 0;
+       b->used = 0;
+       b->free = DIR_BUFFER_SIZE;
+       list_add(&b->head, list);
+
+       return b;
+}
+
+static void vboxsf_dir_buf_free(struct vboxsf_dir_buf *b)
+{
+       list_del(&b->head);
+       kfree(b->buf);
+       kfree(b);
+}
+
+struct vboxsf_dir_info *vboxsf_dir_info_alloc(void)
+{
+       struct vboxsf_dir_info *p;
+
+       p = kmalloc(sizeof(*p), GFP_KERNEL);
+       if (!p)
+               return NULL;
+
+       INIT_LIST_HEAD(&p->info_list);
+       return p;
+}
+
+void vboxsf_dir_info_free(struct vboxsf_dir_info *p)
+{
+       struct list_head *list, *pos, *tmp;
+
+       list = &p->info_list;
+       list_for_each_safe(pos, tmp, list) {
+               struct vboxsf_dir_buf *b;
+
+               b = list_entry(pos, struct vboxsf_dir_buf, head);
+               vboxsf_dir_buf_free(b);
+       }
+       kfree(p);
+}
+
+int vboxsf_dir_read_all(struct vboxsf_sbi *sbi, struct vboxsf_dir_info *sf_d,
+                       u64 handle)
+{
+       struct vboxsf_dir_buf *b;
+       u32 entries, size;
+       int err = 0;
+       void *buf;
+
+       /* vboxsf_dirinfo returns 1 on end of dir */
+       while (err == 0) {
+               b = vboxsf_dir_buf_alloc(&sf_d->info_list);
+               if (!b) {
+                       err = -ENOMEM;
+                       break;
+               }
+
+               buf = b->buf;
+               size = b->free;
+
+               err = vboxsf_dirinfo(sbi->root, handle, NULL, 0, 0,
+                                    &size, buf, &entries);
+               if (err < 0)
+                       break;
+
+               b->entries += entries;
+               b->free -= size;
+               b->used += size;
+       }
+
+       if (b && b->used == 0)
+               vboxsf_dir_buf_free(b);
+
+       /* -EILSEQ means the host could not translate a filename, ignore */
+       if (err > 0 || err == -EILSEQ)
+               err = 0;
+
+       return err;
+}
diff --git a/drivers/staging/vboxsf/vboxsf_wrappers.c 
b/drivers/staging/vboxsf/vboxsf_wrappers.c
new file mode 100644
index 000000000000..bfc78a097dae
--- /dev/null
+++ b/drivers/staging/vboxsf/vboxsf_wrappers.c
@@ -0,0 +1,371 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Wrapper functions for the shfl host calls.
+ *
+ * Copyright (C) 2006-2018 Oracle Corporation
+ */
+
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/vbox_err.h>
+#include <linux/vbox_utils.h>
+#include "vfsmod.h"
+
+#define SHFL_REQUEST \
+       (VMMDEV_REQUESTOR_KERNEL | VMMDEV_REQUESTOR_USR_DRV_OTHER | \
+        VMMDEV_REQUESTOR_CON_DONT_KNOW | VMMDEV_REQUESTOR_TRUST_NOT_GIVEN)
+
+static u32 vboxsf_client_id;
+
+int vboxsf_connect(void)
+{
+       struct vbg_dev *gdev;
+       struct vmmdev_hgcm_service_location loc;
+       int err, vbox_status;
+
+       loc.type = VMMDEV_HGCM_LOC_LOCALHOST_EXISTING;
+       strcpy(loc.u.localhost.service_name, "VBoxSharedFolders");
+
+       gdev = vbg_get_gdev();
+       if (IS_ERR(gdev))
+               return -ENODEV; /* No guest-device */
+
+       err = vbg_hgcm_connect(gdev, SHFL_REQUEST, &loc,
+                              &vboxsf_client_id, &vbox_status);
+       vbg_put_gdev(gdev);
+
+       return err ? err : vbg_status_code_to_errno(vbox_status);
+}
+
+void vboxsf_disconnect(void)
+{
+       struct vbg_dev *gdev;
+       int vbox_status;
+
+       gdev = vbg_get_gdev();
+       if (IS_ERR(gdev))
+               return;   /* guest-device is gone, already disconnected */
+
+       vbg_hgcm_disconnect(gdev, SHFL_REQUEST, vboxsf_client_id, &vbox_status);
+       vbg_put_gdev(gdev);
+}
+
+static int vboxsf_call(u32 function, void *parms, u32 parm_count, int *status)
+{
+       struct vbg_dev *gdev;
+       int err, vbox_status;
+
+       gdev = vbg_get_gdev();
+       if (IS_ERR(gdev))
+               return -ESHUTDOWN; /* guest-dev removed underneath us */
+
+       err = vbg_hgcm_call(gdev, SHFL_REQUEST, vboxsf_client_id, function,
+                           U32_MAX, parms, parm_count, &vbox_status);
+       vbg_put_gdev(gdev);
+
+       if (err < 0)
+               return err;
+
+       if (status)
+               *status = vbox_status;
+
+       return vbg_status_code_to_errno(vbox_status);
+}
+
+int vboxsf_map_folder(struct shfl_string *folder_name, u32 *root)
+{
+       struct shfl_map_folder parms;
+       int err, status;
+
+       parms.path.type = VMMDEV_HGCM_PARM_TYPE_LINADDR_KERNEL;
+       parms.path.u.pointer.size = shfl_string_buf_size(folder_name);
+       parms.path.u.pointer.u.linear_addr = (uintptr_t)folder_name;
+
+       parms.root.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.root.u.value32 = 0;
+
+       parms.delimiter.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.delimiter.u.value32 = '/';
+
+       parms.case_sensitive.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.case_sensitive.u.value32 = 1;
+
+       err = vboxsf_call(SHFL_FN_MAP_FOLDER, &parms, SHFL_CPARMS_MAP_FOLDER,
+                         &status);
+       if (err == -ENOSYS && status == VERR_NOT_IMPLEMENTED)
+               vbg_err("%s: Error host is too old\n", __func__);
+
+       *root = parms.root.u.value32;
+       return err;
+}
+
+int vboxsf_unmap_folder(u32 root)
+{
+       struct shfl_unmap_folder parms;
+
+       parms.root.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.root.u.value32 = root;
+
+       return vboxsf_call(SHFL_FN_UNMAP_FOLDER, &parms,
+                          SHFL_CPARMS_UNMAP_FOLDER, NULL);
+}
+
+/**
+ * vboxsf_create - Create a new file or folder
+ * @root:         Root of the shared folder in which to create the file
+ * @parsed_path:  The path of the file or folder relative to the shared folder
+ * @param:        create_parms Parameters for file/folder creation.
+ *
+ * Create a new file or folder or open an existing one in a shared folder.
+ * Note this function always returns 0 / success unless an exceptional 
condition
+ * occurs - out of memory, invalid arguments, etc. If the file or folder could
+ * not be opened or created, create_parms->handle will be set to
+ * SHFL_HANDLE_NIL on return.  In this case the value in create_parms->result
+ * provides information as to why (e.g. SHFL_FILE_EXISTS), create_parms->result
+ * is also set on success as additional information.
+ *
+ * Returns:
+ * 0 or negative errno value.
+ */
+int vboxsf_create(u32 root, struct shfl_string *parsed_path,
+                 struct shfl_createparms *create_parms)
+{
+       struct shfl_create parms;
+
+       parms.root.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.root.u.value32 = root;
+
+       parms.path.type = VMMDEV_HGCM_PARM_TYPE_LINADDR_KERNEL;
+       parms.path.u.pointer.size = shfl_string_buf_size(parsed_path);
+       parms.path.u.pointer.u.linear_addr = (uintptr_t)parsed_path;
+
+       parms.parms.type = VMMDEV_HGCM_PARM_TYPE_LINADDR_KERNEL;
+       parms.parms.u.pointer.size = sizeof(struct shfl_createparms);
+       parms.parms.u.pointer.u.linear_addr = (uintptr_t)create_parms;
+
+       return vboxsf_call(SHFL_FN_CREATE, &parms, SHFL_CPARMS_CREATE, NULL);
+}
+
+int vboxsf_close(u32 root, u64 handle)
+{
+       struct shfl_close parms;
+
+       parms.root.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.root.u.value32 = root;
+
+       parms.handle.type = VMMDEV_HGCM_PARM_TYPE_64BIT;
+       parms.handle.u.value64 = handle;
+
+       return vboxsf_call(SHFL_FN_CLOSE, &parms, SHFL_CPARMS_CLOSE, NULL);
+}
+
+int vboxsf_remove(u32 root, struct shfl_string *parsed_path, u32 flags)
+{
+       struct shfl_remove parms;
+
+       parms.root.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.root.u.value32 = root;
+
+       parms.path.type = VMMDEV_HGCM_PARM_TYPE_LINADDR_KERNEL_IN;
+       parms.path.u.pointer.size = shfl_string_buf_size(parsed_path);
+       parms.path.u.pointer.u.linear_addr = (uintptr_t)parsed_path;
+
+       parms.flags.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.flags.u.value32 = flags;
+
+       return vboxsf_call(SHFL_FN_REMOVE, &parms, SHFL_CPARMS_REMOVE, NULL);
+}
+
+int vboxsf_rename(u32 root, struct shfl_string *src_path,
+                 struct shfl_string *dest_path, u32 flags)
+{
+       struct shfl_rename parms;
+
+       parms.root.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.root.u.value32 = root;
+
+       parms.src.type = VMMDEV_HGCM_PARM_TYPE_LINADDR_KERNEL_IN;
+       parms.src.u.pointer.size = shfl_string_buf_size(src_path);
+       parms.src.u.pointer.u.linear_addr = (uintptr_t)src_path;
+
+       parms.dest.type = VMMDEV_HGCM_PARM_TYPE_LINADDR_KERNEL_IN;
+       parms.dest.u.pointer.size = shfl_string_buf_size(dest_path);
+       parms.dest.u.pointer.u.linear_addr = (uintptr_t)dest_path;
+
+       parms.flags.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.flags.u.value32 = flags;
+
+       return vboxsf_call(SHFL_FN_RENAME, &parms, SHFL_CPARMS_RENAME, NULL);
+}
+
+int vboxsf_read(u32 root, u64 handle, u64 offset, u32 *buf_len, u8 *buf)
+{
+       struct shfl_read parms;
+       int err;
+
+       parms.root.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.root.u.value32 = root;
+
+       parms.handle.type = VMMDEV_HGCM_PARM_TYPE_64BIT;
+       parms.handle.u.value64 = handle;
+       parms.offset.type = VMMDEV_HGCM_PARM_TYPE_64BIT;
+       parms.offset.u.value64 = offset;
+       parms.cb.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.cb.u.value32 = *buf_len;
+       parms.buffer.type = VMMDEV_HGCM_PARM_TYPE_LINADDR_KERNEL_OUT;
+       parms.buffer.u.pointer.size = *buf_len;
+       parms.buffer.u.pointer.u.linear_addr = (uintptr_t)buf;
+
+       err = vboxsf_call(SHFL_FN_READ, &parms, SHFL_CPARMS_READ, NULL);
+
+       *buf_len = parms.cb.u.value32;
+       return err;
+}
+
+int vboxsf_write(u32 root, u64 handle, u64 offset, u32 *buf_len, u8 *buf)
+{
+       struct shfl_write parms;
+       int err;
+
+       parms.root.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.root.u.value32 = root;
+
+       parms.handle.type = VMMDEV_HGCM_PARM_TYPE_64BIT;
+       parms.handle.u.value64 = handle;
+       parms.offset.type = VMMDEV_HGCM_PARM_TYPE_64BIT;
+       parms.offset.u.value64 = offset;
+       parms.cb.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.cb.u.value32 = *buf_len;
+       parms.buffer.type = VMMDEV_HGCM_PARM_TYPE_LINADDR_KERNEL_IN;
+       parms.buffer.u.pointer.size = *buf_len;
+       parms.buffer.u.pointer.u.linear_addr = (uintptr_t)buf;
+
+       err = vboxsf_call(SHFL_FN_WRITE, &parms, SHFL_CPARMS_WRITE, NULL);
+
+       *buf_len = parms.cb.u.value32;
+       return err;
+}
+
+/* Returns 0 on success, 1 on end-of-dir, negative errno otherwise */
+int vboxsf_dirinfo(u32 root, u64 handle,
+                  struct shfl_string *parsed_path, u32 flags, u32 index,
+                  u32 *buf_len, struct shfl_dirinfo *buf, u32 *file_count)
+{
+       struct shfl_list parms;
+       int err, status;
+
+       parms.root.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.root.u.value32 = root;
+
+       parms.handle.type = VMMDEV_HGCM_PARM_TYPE_64BIT;
+       parms.handle.u.value64 = handle;
+       parms.flags.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.flags.u.value32 = flags;
+       parms.cb.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.cb.u.value32 = *buf_len;
+       if (parsed_path) {
+               parms.path.type = VMMDEV_HGCM_PARM_TYPE_LINADDR_KERNEL_IN;
+               parms.path.u.pointer.size = shfl_string_buf_size(parsed_path);
+               parms.path.u.pointer.u.linear_addr = (uintptr_t)parsed_path;
+       } else {
+               parms.path.type = VMMDEV_HGCM_PARM_TYPE_LINADDR_IN;
+               parms.path.u.pointer.size = 0;
+               parms.path.u.pointer.u.linear_addr = 0;
+       }
+
+       parms.buffer.type = VMMDEV_HGCM_PARM_TYPE_LINADDR_KERNEL_OUT;
+       parms.buffer.u.pointer.size = *buf_len;
+       parms.buffer.u.pointer.u.linear_addr = (uintptr_t)buf;
+
+       parms.resume_point.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.resume_point.u.value32 = index;
+       parms.file_count.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.file_count.u.value32 = 0; /* out parameter only */
+
+       err = vboxsf_call(SHFL_FN_LIST, &parms, SHFL_CPARMS_LIST, &status);
+       if (err == -ENODATA && status == VERR_NO_MORE_FILES)
+               err = 1;
+
+       *buf_len = parms.cb.u.value32;
+       *file_count = parms.file_count.u.value32;
+       return err;
+}
+
+int vboxsf_fsinfo(u32 root, u64 handle, u32 flags,
+                 u32 *buf_len, void *buf)
+{
+       struct shfl_information parms;
+       int err;
+
+       parms.root.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.root.u.value32 = root;
+
+       parms.handle.type = VMMDEV_HGCM_PARM_TYPE_64BIT;
+       parms.handle.u.value64 = handle;
+       parms.flags.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.flags.u.value32 = flags;
+       parms.cb.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.cb.u.value32 = *buf_len;
+       parms.info.type = VMMDEV_HGCM_PARM_TYPE_LINADDR_KERNEL;
+       parms.info.u.pointer.size = *buf_len;
+       parms.info.u.pointer.u.linear_addr = (uintptr_t)buf;
+
+       err = vboxsf_call(SHFL_FN_INFORMATION, &parms, SHFL_CPARMS_INFORMATION,
+                         NULL);
+
+       *buf_len = parms.cb.u.value32;
+       return err;
+}
+
+int vboxsf_readlink(u32 root, struct shfl_string *parsed_path,
+                   u32 buf_len, u8 *buf)
+{
+       struct shfl_readLink parms;
+
+       parms.root.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.root.u.value32 = root;
+
+       parms.path.type = VMMDEV_HGCM_PARM_TYPE_LINADDR_KERNEL_IN;
+       parms.path.u.pointer.size = shfl_string_buf_size(parsed_path);
+       parms.path.u.pointer.u.linear_addr = (uintptr_t)parsed_path;
+
+       parms.buffer.type = VMMDEV_HGCM_PARM_TYPE_LINADDR_KERNEL_OUT;
+       parms.buffer.u.pointer.size = buf_len;
+       parms.buffer.u.pointer.u.linear_addr = (uintptr_t)buf;
+
+       return vboxsf_call(SHFL_FN_READLINK, &parms, SHFL_CPARMS_READLINK,
+                          NULL);
+}
+
+int vboxsf_symlink(u32 root, struct shfl_string *new_path,
+                  struct shfl_string *old_path, struct shfl_fsobjinfo *buf)
+{
+       struct shfl_symlink parms;
+
+       parms.root.type = VMMDEV_HGCM_PARM_TYPE_32BIT;
+       parms.root.u.value32 = root;
+
+       parms.new_path.type = VMMDEV_HGCM_PARM_TYPE_LINADDR_KERNEL_IN;
+       parms.new_path.u.pointer.size = shfl_string_buf_size(new_path);
+       parms.new_path.u.pointer.u.linear_addr = (uintptr_t)new_path;
+
+       parms.old_path.type = VMMDEV_HGCM_PARM_TYPE_LINADDR_KERNEL_IN;
+       parms.old_path.u.pointer.size = shfl_string_buf_size(old_path);
+       parms.old_path.u.pointer.u.linear_addr = (uintptr_t)old_path;
+
+       parms.info.type = VMMDEV_HGCM_PARM_TYPE_LINADDR_KERNEL_OUT;
+       parms.info.u.pointer.size = sizeof(struct shfl_fsobjinfo);
+       parms.info.u.pointer.u.linear_addr = (uintptr_t)buf;
+
+       return vboxsf_call(SHFL_FN_SYMLINK, &parms, SHFL_CPARMS_SYMLINK, NULL);
+}
+
+int vboxsf_set_utf8(void)
+{
+       return vboxsf_call(SHFL_FN_SET_UTF8, NULL, 0, NULL);
+}
+
+int vboxsf_set_symlinks(void)
+{
+       return vboxsf_call(SHFL_FN_SET_SYMLINKS, NULL, 0, NULL);
+}
diff --git a/drivers/staging/vboxsf/vfsmod.h b/drivers/staging/vboxsf/vfsmod.h
new file mode 100644
index 000000000000..de650d65fbe4
--- /dev/null
+++ b/drivers/staging/vboxsf/vfsmod.h
@@ -0,0 +1,138 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * VirtualBox Guest Shared Folders support: module header.
+ *
+ * Copyright (C) 2006-2018 Oracle Corporation
+ */
+
+#ifndef VFSMOD_H
+#define VFSMOD_H
+
+#include <linux/backing-dev.h>
+#include <linux/idr.h>
+#include <linux/version.h>
+#include "shfl_hostintf.h"
+
+#define DIR_BUFFER_SIZE SZ_16K
+
+/* The cast is to prevent assignment of void * to pointers of arbitrary type */
+#define VBOXSF_SBI(sb) ((struct vboxsf_sbi *)(sb)->s_fs_info)
+#define VBOXSF_I(i)    container_of(i, struct vboxsf_inode, vfs_inode)
+
+struct vboxsf_options {
+       unsigned long ttl;
+       kuid_t uid;
+       kgid_t gid;
+       bool dmode_set;
+       bool fmode_set;
+       umode_t dmode;
+       umode_t fmode;
+       umode_t dmask;
+       umode_t fmask;
+};
+
+struct vboxsf_fs_context {
+       struct vboxsf_options o;
+       char *nls_name;
+};
+
+/* per-shared folder information */
+struct vboxsf_sbi {
+       struct vboxsf_options o;
+       struct shfl_fsobjinfo root_info;
+       struct idr ino_idr;
+       spinlock_t ino_idr_lock; /* This protects ino_idr */
+       struct nls_table *nls;
+       u32 next_generation;
+       u32 root;
+       int bdi_id;
+};
+
+/* per-inode information */
+struct vboxsf_inode {
+       /* some information was changed, update data on next revalidate */
+       int force_restat;
+       /* list of open handles for this inode + lock protecting it */
+       struct list_head handle_list;
+       /* This mutex protects handle_list accesses */
+       struct mutex handle_list_mutex;
+       /* The VFS inode struct */
+       struct inode vfs_inode;
+};
+
+struct vboxsf_dir_info {
+       struct list_head info_list;
+};
+
+struct vboxsf_dir_buf {
+       size_t entries;
+       size_t free;
+       size_t used;
+       void *buf;
+       struct list_head head;
+};
+
+/* globals */
+extern const struct inode_operations vboxsf_dir_iops;
+extern const struct inode_operations vboxsf_lnk_iops;
+extern const struct inode_operations vboxsf_reg_iops;
+extern const struct file_operations vboxsf_dir_fops;
+extern const struct file_operations vboxsf_reg_fops;
+extern const struct address_space_operations vboxsf_reg_aops;
+extern const struct dentry_operations vboxsf_dentry_ops;
+
+/* from utils.c */
+struct inode *vboxsf_new_inode(struct super_block *sb);
+void vboxsf_init_inode(struct vboxsf_sbi *sbi, struct inode *inode,
+                      const struct shfl_fsobjinfo *info);
+int vboxsf_create_at_dentry(struct dentry *dentry,
+                           struct shfl_createparms *params);
+int vboxsf_stat(struct vboxsf_sbi *sbi, struct shfl_string *path,
+               struct shfl_fsobjinfo *info);
+int vboxsf_stat_dentry(struct dentry *dentry, struct shfl_fsobjinfo *info);
+int vboxsf_inode_revalidate(struct dentry *dentry);
+int vboxsf_getattr(const struct path *path, struct kstat *kstat,
+                  u32 request_mask, unsigned int query_flags);
+int vboxsf_setattr(struct dentry *dentry, struct iattr *iattr);
+struct shfl_string *vboxsf_path_from_dentry(struct vboxsf_sbi *sbi,
+                                           struct dentry *dentry);
+int vboxsf_nlscpy(struct vboxsf_sbi *sbi, char *name, size_t name_bound_len,
+                 const unsigned char *utf8_name, size_t utf8_len);
+struct vboxsf_dir_info *vboxsf_dir_info_alloc(void);
+void vboxsf_dir_info_free(struct vboxsf_dir_info *p);
+int vboxsf_dir_read_all(struct vboxsf_sbi *sbi, struct vboxsf_dir_info *sf_d,
+                       u64 handle);
+
+/* from vboxsf_wrappers.c */
+int vboxsf_connect(void);
+void vboxsf_disconnect(void);
+
+int vboxsf_create(u32 root, struct shfl_string *parsed_path,
+                 struct shfl_createparms *create_parms);
+
+int vboxsf_close(u32 root, u64 handle);
+int vboxsf_remove(u32 root, struct shfl_string *parsed_path, u32 flags);
+int vboxsf_rename(u32 root, struct shfl_string *src_path,
+                 struct shfl_string *dest_path, u32 flags);
+
+int vboxsf_read(u32 root, u64 handle, u64 offset, u32 *buf_len, u8 *buf);
+int vboxsf_write(u32 root, u64 handle, u64 offset, u32 *buf_len, u8 *buf);
+
+int vboxsf_dirinfo(u32 root, u64 handle,
+                  struct shfl_string *parsed_path, u32 flags, u32 index,
+                  u32 *buf_len, struct shfl_dirinfo *buf, u32 *file_count);
+int vboxsf_fsinfo(u32 root, u64 handle, u32 flags,
+                 u32 *buf_len, void *buf);
+
+int vboxsf_map_folder(struct shfl_string *folder_name, u32 *root);
+int vboxsf_unmap_folder(u32 root);
+
+int vboxsf_readlink(u32 root, struct shfl_string *parsed_path,
+                   u32 buf_len, u8 *buf);
+int vboxsf_symlink(u32 root, struct shfl_string *new_path,
+                  struct shfl_string *old_path, struct shfl_fsobjinfo *buf);
+
+int vboxsf_set_utf8(void);
+int vboxsf_set_symlinks(void);
+
+#endif
-- 
2.23.0

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