On Wed 04-12-24 17:23:25, I Hsin Cheng wrote:
> As the implementation of "f->f_pos_lock" may change in the future,
> wrapping the actual implementation of locking and unlocking of it can
> provide better decoupling semantics.
>
> "__f_unlock_pos()" already exist and does that, adding "__f_lock_pos()"
> can provide full decoupling.
>
> Signed-off-by: I Hsin Cheng <richard120310@xxxxxxxxx>
I guess this would make sense for consistence. But Al, what was the
motivation of introducing __f_unlock_pos() in the first place? It has one
caller and was silently introduced in 63b6df14134d ("give
readdir(2)/getdents(2)/etc. uniform exclusion with lseek()") about 8 years
ago.
Honza
> ---
> fs/file.c | 7 ++++++-
> include/linux/file.h | 1 +
> 2 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/fs/file.c b/fs/file.c
> index fb1011cf6b4a..b93ac67d276d 100644
> --- a/fs/file.c
> +++ b/fs/file.c
> @@ -1181,6 +1181,11 @@ static inline bool file_needs_f_pos_lock(struct file *file)
> (file_count(file) > 1 || file->f_op->iterate_shared);
> }
>
> +void __f_lock_pos(struct file *f)
> +{
> + mutex_lock(&f->f_pos_lock);
> +}
> +
> struct fd fdget_pos(unsigned int fd)
> {
> struct fd f = fdget(fd);
> @@ -1188,7 +1193,7 @@ struct fd fdget_pos(unsigned int fd)
>
> if (file && file_needs_f_pos_lock(file)) {
> f.word |= FDPUT_POS_UNLOCK;
> - mutex_lock(&file->f_pos_lock);
> + __f_lock_pos(file);
> }
> return f;
> }
> diff --git a/include/linux/file.h b/include/linux/file.h
> index 302f11355b10..16292bd95499 100644
> --- a/include/linux/file.h
> +++ b/include/linux/file.h
> @@ -67,6 +67,7 @@ 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_lock_pos(struct file *file);
> extern void __f_unlock_pos(struct file *);
>
> struct fd fdget(unsigned int fd);
> --
> 2.43.0
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
