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add struct fd constructors, get rid of __to_fd()

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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 <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2024-05-31 16:34:25 -04:00
parent 88a2f6468d
commit de12c3391b
2 changed files with 24 additions and 35 deletions
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26
fs/file.c
View File

@ -1128,7 +1128,7 @@ EXPORT_SYMBOL(task_lookup_next_fdget_rcu);
* The fput_needed flag returned by fget_light should be passed to the * The fput_needed flag returned by fget_light should be passed to the
* corresponding fput_light. * 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 files_struct *files = current->files;
struct file *file; 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)) { if (likely(atomic_read_acquire(&files->count) == 1)) {
file = files_lookup_fd_raw(files, fd); file = files_lookup_fd_raw(files, fd);
if (!file || unlikely(file->f_mode & mask)) if (!file || unlikely(file->f_mode & mask))
return 0; return EMPTY_FD;
return (unsigned long)file; return BORROWED_FD(file);
} else { } else {
file = __fget_files(files, fd, mask); file = __fget_files(files, fd, mask);
if (!file) if (!file)
return 0; return EMPTY_FD;
return FDPUT_FPUT | (unsigned long)file; return CLONED_FD(file);
} }
} }
unsigned long __fdget(unsigned int fd) struct fd fdget(unsigned int fd)
{ {
return __fget_light(fd, FMODE_PATH); 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); 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); (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 fd f = fdget(fd);
struct file *file = (struct file *)(v & ~3); struct file *file = fd_file(f);
if (file && file_needs_f_pos_lock(file)) { if (file && file_needs_f_pos_lock(file)) {
v |= FDPUT_POS_UNLOCK; f.word |= FDPUT_POS_UNLOCK;
mutex_lock(&file->f_pos_lock); mutex_lock(&file->f_pos_lock);
} }
return v; return f;
} }
void __f_unlock_pos(struct file *f) void __f_unlock_pos(struct file *f)

33
include/linux/file.h
View File

@ -53,6 +53,14 @@ static inline bool fd_empty(struct fd f)
} }
#define EMPTY_FD (struct fd){0} #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) 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(unsigned int fd);
extern struct file *fget_raw(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(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 *); extern void __f_unlock_pos(struct file *);
static inline struct fd __to_fd(unsigned long v) struct fd fdget(unsigned int fd);
{ struct fd fdget_raw(unsigned int fd);
return (struct fd){v}; struct fd fdget_pos(unsigned int fd);
}
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));
}
static inline void fdput_pos(struct fd f) static inline void fdput_pos(struct fd f)
{ {