add struct fd constructors, get rid of __to_fd()

	Make __fdget() et.al. return struct fd directly.
New helpers: BORROWED_FD(file) and CLONED_FD(file), for
borrowed and cloned file references resp.

	NOTE: this might need tuning; in particular, inline on
__fget_light() is there to keep the code generation same as
before - we probably want to keep it inlined in fdget() et.al.
(especially so in fdget_pos()), but that needs profiling.

Reviewed-by: Christian Brauner <[email protected]>
Signed-off-by: Al Viro <[email protected]>

diff --git a/fs/file.c b/fs/file.c
index a3b72aa64f1164380fdaa6524081a4ac956831da..6f5ed4daafd28f64dea8340b514cbbf0815527b9 100644 (file)
--- a/fs/file.c
+++ b/fs/file.c
@@ -1128,7 +1128,7 @@ EXPORT_SYMBOL(task_lookup_next_fdget_rcu);
  * The fput_needed flag returned by fget_light should be passed to the
  * corresponding fput_light.
  */
-static unsigned long __fget_light(unsigned int fd, fmode_t mask)
+static inline struct fd __fget_light(unsigned int fd, fmode_t mask)
 {
        struct files_struct *files = current->files;
        struct file *file;
@@ -1145,22 +1145,22 @@ static unsigned long __fget_light(unsigned int fd, fmode_t mask)
        if (likely(atomic_read_acquire(&files->count) == 1)) {
                file = files_lookup_fd_raw(files, fd);
                if (!file || unlikely(file->f_mode & mask))
-                       return 0;
-               return (unsigned long)file;
+                       return EMPTY_FD;
+               return BORROWED_FD(file);
        } else {
                file = __fget_files(files, fd, mask);
                if (!file)
-                       return 0;
-               return FDPUT_FPUT | (unsigned long)file;
+                       return EMPTY_FD;
+               return CLONED_FD(file);
        }
 }
-unsigned long __fdget(unsigned int fd)
+struct fd fdget(unsigned int fd)
 {
        return __fget_light(fd, FMODE_PATH);
 }
-EXPORT_SYMBOL(__fdget);
+EXPORT_SYMBOL(fdget);
 
-unsigned long __fdget_raw(unsigned int fd)
+struct fd fdget_raw(unsigned int fd)
 {
        return __fget_light(fd, 0);
 }
@@ -1181,16 +1181,16 @@ static inline bool file_needs_f_pos_lock(struct file *file)
                (file_count(file) > 1 || file->f_op->iterate_shared);
 }
 
-unsigned long __fdget_pos(unsigned int fd)
+struct fd fdget_pos(unsigned int fd)
 {
-       unsigned long v = __fdget(fd);
-       struct file *file = (struct file *)(v & ~3);
+       struct fd f = fdget(fd);
+       struct file *file = fd_file(f);
 
        if (file && file_needs_f_pos_lock(file)) {
-               v |= FDPUT_POS_UNLOCK;
+               f.word |= FDPUT_POS_UNLOCK;
                mutex_lock(&file->f_pos_lock);
        }
-       return v;
+       return f;
 }
 
 void __f_unlock_pos(struct file *f)

diff --git a/include/linux/file.h b/include/linux/file.h
index eb28469b1c161204b4eccf8568fc967fc8e940e2..aab1caff671348407673bd49d0cc95d88ff64dd3 100644 (file)
--- a/include/linux/file.h
+++ b/include/linux/file.h
@@ -53,6 +53,14 @@ static inline bool fd_empty(struct fd f)
 }
 
 #define EMPTY_FD (struct fd){0}
+static inline struct fd BORROWED_FD(struct file *f)
+{
+       return (struct fd){(unsigned long)f};
+}
+static inline struct fd CLONED_FD(struct file *f)
+{
+       return (struct fd){(unsigned long)f | FDPUT_FPUT};
+}
 
 static inline void fdput(struct fd fd)
 {
@@ -63,30 +71,11 @@ static inline void fdput(struct fd 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 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)
-{
-       return (struct fd){v};
-}
-
-static inline struct fd fdget(unsigned int fd)
-{
-       return __to_fd(__fdget(fd));
-}
-
-static inline struct fd fdget_raw(unsigned int fd)
-{
-       return __to_fd(__fdget_raw(fd));
-}
-
-static inline struct fd fdget_pos(int fd)
-{
-       return __to_fd(__fdget_pos(fd));
-}
+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)
 {