[PATCH v10 0/1] fs: Add VirtualBox guest shared folder (vboxsf) support

[Hans de Goede <hdegoede@redhat.com>]

Hello Everyone,

Here is the 10th version of my cleaned-up / refactored version of the
VirtualBox shared-folder VFS driver.

This version hopefully addresses all issues pointed out in Al's detailed
review of v9 (thank you for the review Al):

Changes in v10:
-Code-style fixes and remove some unneeded checks as suggested by Al Viro
-Stop handle reuse between sf_create_aux and sf_reg_open, the code for this
 was racy and the re-use meant the O_APPEND was not passed to the host for
 newly created files with O_APPEND set
-Use idr to generate unique inode number, modelled after the kernfs code
-Only read and write the contents of the passed in offset pointer once in
 sf_reg_write
-Keep a list of refcounted open handles in the inode, so that writepage can
 get a writeable handle this way. This replaces the old very racy code which
 was just storing a pointer to the last opened struct file inside the inode.
 This is modelled after how the cifs and fuse code do this

For changes in older versions see the change log in the patch.

This version has been used by several distributions (arch, Fedora) for a
while now, so hopefully we can get this upstream soonish, please review.

Regards,

Hans