On Tue, Jul 11, 2023 at 07:40:26PM +0800, Hao Xu wrote:
> From: Hao Xu <howeyxu@xxxxxxxxxxx>
>
> The flags will allow passing DIR_CONTEXT_F_NOWAIT to iterate()
> implementations that support it (as signaled through FMODE_NWAIT
> in file->f_mode)
>
> Notes:
> - considered using IOCB_NOWAIT but if we add more flags later it
> would be confusing to keep track of which values are valid, use
> dedicated flags
> - might want to check ctx.flags & DIR_CONTEXT_F_NOWAIT is only set
> when file->f_mode & FMODE_NOWAIT in iterate_dir() as e.g. WARN_ONCE?
>
> Co-developed-by: Dominique Martinet <asmadeus@xxxxxxxxxxxxx>
> Signed-off-by: Dominique Martinet <asmadeus@xxxxxxxxxxxxx>
> Signed-off-by: Hao Xu <howeyxu@xxxxxxxxxxx>
> ---
> fs/internal.h | 2 +-
> fs/readdir.c | 6 ++++--
> include/linux/fs.h | 8 ++++++++
> 3 files changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/fs/internal.h b/fs/internal.h
> index b1f66e52d61b..7508d485c655 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -311,4 +311,4 @@ void mnt_idmap_put(struct mnt_idmap *idmap);
> struct linux_dirent64;
>
> int vfs_getdents(struct file *file, struct linux_dirent64 __user *dirent,
> - unsigned int count);
> + unsigned int count, unsigned long flags);
> diff --git a/fs/readdir.c b/fs/readdir.c
> index 9592259b7e7f..b80caf4c9321 100644
> --- a/fs/readdir.c
> +++ b/fs/readdir.c
> @@ -358,12 +358,14 @@ static bool filldir64(struct dir_context *ctx, const char *name, int namlen,
> * @file : pointer to file struct of directory
> * @dirent : pointer to user directory structure
> * @count : size of buffer
> + * @flags : additional dir_context flags
Why do you need that flag argument. The ->iterate{_shared}() i_op gets
passed the file so the filesystem can check
@file->f_mode & FMODE_NOWAIT, no?
> */
> int vfs_getdents(struct file *file, struct linux_dirent64 __user *dirent,
> - unsigned int count)
> + unsigned int count, unsigned long flags)
> {
> struct getdents_callback64 buf = {
> .ctx.actor = filldir64,
> + .ctx.flags = flags,
> .count = count,
> .current_dir = dirent
> };
> @@ -395,7 +397,7 @@ SYSCALL_DEFINE3(getdents64, unsigned int, fd,
> if (!f.file)
> return -EBADF;
>
> - error = vfs_getdents(f.file, dirent, count);
> + error = vfs_getdents(f.file, dirent, count, 0);
>
> fdput_pos(f);
> return error;
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 6867512907d6..f3e315e8efdd 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1719,8 +1719,16 @@ typedef bool (*filldir_t)(struct dir_context *, const char *, int, loff_t, u64,
> struct dir_context {
> filldir_t actor;
> loff_t pos;
> + unsigned long flags;
> };
>
> +/*
> + * flags for dir_context flags
> + * DIR_CONTEXT_F_NOWAIT: Request non-blocking iterate
> + * (requires file->f_mode & FMODE_NOWAIT)
> + */
> +#define DIR_CONTEXT_F_NOWAIT (1 << 0)
Even if this should be needed, I don't think this needs to use a full
flags field.
