1 files changed, 52 insertions, 32 deletions

diff --git a/include/linux/file.h b/include/linux/file.h
index 169692cb1906..af1768d934a0 100644
--- a/include/linux/file.h
+++ b/include/linux/file.h
@@ -11,6 +11,7 @@
 #include <linux/posix_types.h>
 #include <linux/errno.h>
 #include <linux/cleanup.h>
+#include <linux/err.h>
 
 struct file;
 
@@ -29,61 +30,59 @@ extern struct file *alloc_file_pseudo_noaccount(struct inode *, struct vfsmount
 extern struct file *alloc_file_clone(struct file *, int flags,
 	const struct file_operations *);
 
-static inline void fput_light(struct file *file, int fput_needed)
-{
-	if (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 (unlikely(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 struct file *fget_task_next(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);
 }
 
 DEFINE_CLASS(fd, struct fd, fdput(_T), fdget(fd), int fd)
+DEFINE_CLASS(fd_raw, struct fd, fdput(_T), fdget_raw(fd), int fd)
+DEFINE_CLASS(fd_pos, struct fd, fdput_pos(_T), fdget_pos(fd), int fd)
 
 extern int f_dupfd(unsigned int from, struct file *file, unsigned flags);
 extern int replace_fd(unsigned fd, struct file *file, unsigned flags);
@@ -95,6 +94,27 @@ extern void put_unused_fd(unsigned int fd);
 
 DEFINE_CLASS(get_unused_fd, int, if (_T >= 0) put_unused_fd(_T),
 	     get_unused_fd_flags(flags), unsigned flags)
+DEFINE_FREE(fput, struct file *, if (!IS_ERR_OR_NULL(_T)) fput(_T))
+
+/*
+ * take_fd() will take care to set @fd to -EBADF ensuring that
+ * CLASS(get_unused_fd) won't call put_unused_fd(). This makes it
+ * easier to rely on CLASS(get_unused_fd):
+ *
+ * struct file *f;
+ *
+ * CLASS(get_unused_fd, fd)(O_CLOEXEC);
+ * if (fd < 0)
+ *         return fd;
+ *
+ * f = dentry_open(&path, O_RDONLY, current_cred());
+ * if (IS_ERR(f))
+ *         return PTR_ERR(f);
+ *
+ * fd_install(fd, f);
+ * return take_fd(fd);
+ */
+#define take_fd(fd) __get_and_null(fd, -EBADF)
 
 extern void fd_install(unsigned int fd, struct file *file);