vfs: open inside ->tmpfile()

This is in preparation for adding tmpfile support to fuse, which requires
that the tmpfile creation and opening are done as a single operation.

Replace the 'struct dentry *' argument of i_op->tmpfile with
'struct file *'.

Call finish_open_simple() as the last thing in ->tmpfile() instances (may
be omitted in the error case).

Change d_tmpfile() argument to 'struct file *' as well to make callers more
readable.

Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst
index aee9aaf9f3df..af138241bb4b 100644
--- a/Documentation/filesystems/porting.rst
+++ b/Documentation/filesystems/porting.rst
@@ -922,3 +922,13 @@ is provided - file_open_root_mnt().  In-tree users adjusted.
 no_llseek is gone; don't set .llseek to that - just leave it NULL instead.
 Checks for "does that file have llseek(2), or should it fail with ESPIPE"
 should be done by looking at FMODE_LSEEK in file->f_mode.
+
+---
+
+**mandatory**
+
+Calling conventions for ->tmpfile() have changed.  It now takes a struct
+file pointer instead of struct dentry pointer.  d_tmpfile() is similarly
+changed to simplify callers.  The passed file is in a non-open state and on
+success must be opened before returning (e.g. by calling
+finish_open_simple()).