Merge tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull 'struct fd' updates from Al Viro:
 "Just the 'struct fd' layout change, with conversion to accessor
  helpers"

* tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  add struct fd constructors, get rid of __to_fd()
  struct fd: representation change
  introduce fd_file(), convert all accessors to it.

2 files changed, 28 insertions, 27 deletions

diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
index d9e613803df1..a3d3e888cf1f 100644
--- a/include/linux/cleanup.h
+++ b/include/linux/cleanup.h
@@ -98,7 +98,7 @@ const volatile void * __must_check_fn(const volatile void *val)
  * DEFINE_CLASS(fdget, struct fd, fdput(_T), fdget(fd), int fd)
  *
  *	CLASS(fdget, f)(fd);
- *	if (!f.file)
+ *	if (!fd_file(f))
  *		return -EBADF;
  *
  *	// use 'f' without concern
diff --git a/include/linux/file.h b/include/linux/file.h
index 6bd9cd9c87e5..f98de143245a 100644
--- a/include/linux/file.h
+++ b/include/linux/file.h
@@ -36,51 +36,52 @@ static inline void fput_light(struct file *file, int fput_needed)
 		fput(file);
 }
 
+/* either a reference to struct file + flags
+ * (cloned vs. borrowed, pos locked), with
+ * flags stored in lower bits of value,
+ * or empty (represented by 0).
+ */
 struct fd {
-	struct file *file;
-	unsigned int flags;
+	unsigned long word;
 };
 #define FDPUT_FPUT       1
 #define FDPUT_POS_UNLOCK 2
 
-static inline void fdput(struct fd fd)
+#define fd_file(f) ((struct file *)((f).word & ~(FDPUT_FPUT|FDPUT_POS_UNLOCK)))
+static inline bool fd_empty(struct fd f)
 {
-	if (fd.flags & FDPUT_FPUT)
-		fput(fd.file);
+	return unlikely(!f.word);
 }
 
-extern struct file *fget(unsigned int fd);
-extern struct file *fget_raw(unsigned int fd);
-extern struct file *fget_task(struct task_struct *task, unsigned int fd);
-extern unsigned long __fdget(unsigned int fd);
-extern unsigned long __fdget_raw(unsigned int fd);
-extern unsigned long __fdget_pos(unsigned int fd);
-extern void __f_unlock_pos(struct file *);
-
-static inline struct fd __to_fd(unsigned long v)
+#define EMPTY_FD (struct fd){0}
+static inline struct fd BORROWED_FD(struct file *f)
 {
-	return (struct fd){(struct file *)(v & ~3),v & 3};
+	return (struct fd){(unsigned long)f};
 }
-
-static inline struct fd fdget(unsigned int fd)
+static inline struct fd CLONED_FD(struct file *f)
 {
-	return __to_fd(__fdget(fd));
+	return (struct fd){(unsigned long)f | FDPUT_FPUT};
 }
 
-static inline struct fd fdget_raw(unsigned int fd)
+static inline void fdput(struct fd fd)
 {
-	return __to_fd(__fdget_raw(fd));
+	if (fd.word & FDPUT_FPUT)
+		fput(fd_file(fd));
 }
 
-static inline struct fd fdget_pos(int fd)
-{
-	return __to_fd(__fdget_pos(fd));
-}
+extern struct file *fget(unsigned int fd);
+extern struct file *fget_raw(unsigned int fd);
+extern struct file *fget_task(struct task_struct *task, unsigned int fd);
+extern void __f_unlock_pos(struct file *);
+
+struct fd fdget(unsigned int fd);
+struct fd fdget_raw(unsigned int fd);
+struct fd fdget_pos(unsigned int fd);
 
 static inline void fdput_pos(struct fd f)
 {
-	if (f.flags & FDPUT_POS_UNLOCK)
-		__f_unlock_pos(f.file);
+	if (f.word & FDPUT_POS_UNLOCK)
+		__f_unlock_pos(fd_file(f));
 	fdput(f);
 }