Use a 'struct fd_cookie *' type for light fd handling rather than an unsigned long so that confusion doesn't arise with integer fd numbers.
I have a use case where I want to store this in struct nameidata, but don't want to expand it to a struct fd to save space. Signed-off-by: David Howells <[email protected]> --- fs/file.c | 20 +++++++++++--------- include/linux/file.h | 31 ++++++++++++++++++++++++------- 2 files changed, 35 insertions(+), 16 deletions(-) diff --git a/fs/file.c b/fs/file.c index 7ffd6e9d103d..8b0012ddadad 100644 --- a/fs/file.c +++ b/fs/file.c @@ -727,7 +727,7 @@ EXPORT_SYMBOL(fget_raw); * 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 struct fd_cookie *__fget_light(unsigned int fd, fmode_t mask) { struct files_struct *files = current->files; struct file *file; @@ -736,33 +736,35 @@ static unsigned long __fget_light(unsigned int fd, fmode_t mask) file = __fcheck_files(files, fd); if (!file || unlikely(file->f_mode & mask)) return 0; - return (unsigned long)file; + return (struct fd_cookie *)file; } else { file = __fget(fd, mask); if (!file) return 0; - return FDPUT_FPUT | (unsigned long)file; + return (struct fd_cookie *)(FDPUT_FPUT | (unsigned long)file); } } -unsigned long __fdget(unsigned int fd) + +struct fd_cookie *__fdget(unsigned int fd) { return __fget_light(fd, FMODE_PATH); } EXPORT_SYMBOL(__fdget); -unsigned long __fdget_raw(unsigned int fd) +struct fd_cookie *__fdget_raw(unsigned int fd) { return __fget_light(fd, 0); } -unsigned long __fdget_pos(unsigned int fd) +struct fd_cookie *__fdget_pos(unsigned int fd) { - unsigned long v = __fdget(fd); - struct file *file = (struct file *)(v & ~3); + struct fd_cookie *v = __fdget(fd); + struct file *file = __fdfile(v); if (file && (file->f_mode & FMODE_ATOMIC_POS)) { if (file_count(file) > 1) { - v |= FDPUT_POS_UNLOCK; + v = (struct fd_cookie *) + ((unsigned long)v | FDPUT_POS_UNLOCK); mutex_lock(&file->f_pos_lock); } } diff --git a/include/linux/file.h b/include/linux/file.h index 279720db984a..3fce1c92b576 100644 --- a/include/linux/file.h +++ b/include/linux/file.h @@ -11,6 +11,7 @@ #include <linux/posix_types.h> struct file; +struct fd_cookie; /* Deliberately undefined structure */ extern void fput(struct file *); @@ -31,8 +32,24 @@ struct fd { struct file *file; unsigned int flags; }; -#define FDPUT_FPUT 1 -#define FDPUT_POS_UNLOCK 2 +#define FDPUT_FPUT 1 +#define FDPUT_POS_UNLOCK 2 +#define FDPUT__MASK 3 + +static inline unsigned long __fdflags(struct fd_cookie *f) +{ + return (unsigned long)f & FDPUT__MASK; +} + +static inline struct file *__fdfile(struct fd_cookie *f) +{ + return (struct file *)((unsigned long)f & ~FDPUT__MASK); +} + +static inline void __fdput(struct fd_cookie *f) +{ + fput_light(__fdfile(f), __fdflags(f) & FDPUT_FPUT); +} static inline void fdput(struct fd fd) { @@ -42,14 +59,14 @@ static inline void fdput(struct fd fd) extern struct file *fget(unsigned int fd); extern struct file *fget_raw(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 struct fd_cookie * __fdget(unsigned int fd); +extern struct fd_cookie *__fdget_raw(unsigned int fd); +extern struct fd_cookie *__fdget_pos(unsigned int fd); extern void __f_unlock_pos(struct file *); -static inline struct fd __to_fd(unsigned long v) +static inline struct fd __to_fd(struct fd_cookie *v) { - return (struct fd){(struct file *)(v & ~3),v & 3}; + return (struct fd){__fdfile(v), __fdflags(v)}; } static inline struct fd fdget(unsigned int fd)
