2023-04-22 08:44:18

by Dominique Martinet

Subject: [PATCH RFC 1/2] fs: split off vfs_getdents function of getdents64 syscall

This splits off the vfs_getdents function from the getdents64 system
call.
This will allow io_uring to call the vfs_getdents function.

Co-authored-by: Stefan Roesch <[email protected]>
Signed-off-by: Dominique Martinet <[email protected]>
---
fs/internal.h | 8 ++++++++
fs/readdir.c | 33 +++++++++++++++++++++++++--------
2 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/fs/internal.h b/fs/internal.h
index dc4eb91a577a..92eeaf3837d1 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -264,3 +264,11 @@ int setattr_should_drop_sgid(struct mnt_idmap *idmap,
struct mnt_idmap *alloc_mnt_idmap(struct user_namespace *mnt_userns);
struct mnt_idmap *mnt_idmap_get(struct mnt_idmap *idmap);
void mnt_idmap_put(struct mnt_idmap *idmap);
+
+/*
+ * fs/readdir.c
+ */
+struct linux_dirent64;
+
+int vfs_getdents(struct file *file, struct linux_dirent64 __user *dirent,
+ unsigned int count);
diff --git a/fs/readdir.c b/fs/readdir.c
index 9c53edb60c03..1d541a6f2d55 100644
--- a/fs/readdir.c
+++ b/fs/readdir.c
@@ -351,10 +351,16 @@ static bool filldir64(struct dir_context *ctx, const char *name, int namlen,
return false;
}

-SYSCALL_DEFINE3(getdents64, unsigned int, fd,
- struct linux_dirent64 __user *, dirent, unsigned int, count)
+
+/**
+ * vfs_getdents - getdents without fdget
+ * @file : pointer to file struct of directory
+ * @dirent : pointer to user directory structure
+ * @count : size of buffer
+ */
+int vfs_getdents(struct file *file, struct linux_dirent64 __user *dirent,
+ unsigned int count)
{
- struct fd f;
struct getdents_callback64 buf = {
.ctx.actor = filldir64,
.count = count,
@@ -362,11 +368,7 @@ SYSCALL_DEFINE3(getdents64, unsigned int, fd,
};
int error;

- f = fdget_pos(fd);
- if (!f.file)
- return -EBADF;
-
- error = iterate_dir(f.file, &buf.ctx);
+ error = iterate_dir(file, &buf.ctx);
if (error >= 0)
error = buf.error;
if (buf.prev_reclen) {
@@ -379,6 +381,21 @@ SYSCALL_DEFINE3(getdents64, unsigned int, fd,
else
error = count - buf.count;
}
+ return error;
+}
+
+SYSCALL_DEFINE3(getdents64, unsigned int, fd,
+ struct linux_dirent64 __user *, dirent, unsigned int, count)
+{
+ struct fd f;
+ int error;
+
+ f = fdget_pos(fd);
+ if (!f.file)
+ return -EBADF;
+
+ error = vfs_getdents(f.file, dirent, count);
+
fdput_pos(f);
return error;
}

--
2.39.2

2023-04-22 10:44:04

by Dominique Martinet

Subject: Re: [PATCH RFC 1/2] fs: split off vfs_getdents function of getdents64 syscall

Dominique Martinet wrote on Sat, Apr 22, 2023 at 05:40:18PM +0900:
> This splits off the vfs_getdents function from the getdents64 system
> call.
> This will allow io_uring to call the vfs_getdents function.
>
> Co-authored-by: Stefan Roesch <[email protected]>
> Signed-off-by: Dominique Martinet <[email protected]>
> ---
> fs/internal.h | 8 ++++++++
> fs/readdir.c | 33 +++++++++++++++++++++++++--------
> 2 files changed, 33 insertions(+), 8 deletions(-)
>
> diff --git a/fs/internal.h b/fs/internal.h
> index dc4eb91a577a..92eeaf3837d1 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -264,3 +264,11 @@ int setattr_should_drop_sgid(struct mnt_idmap *idmap,
> struct mnt_idmap *alloc_mnt_idmap(struct user_namespace *mnt_userns);
> struct mnt_idmap *mnt_idmap_get(struct mnt_idmap *idmap);
> void mnt_idmap_put(struct mnt_idmap *idmap);
> +
> +/*
> + * fs/readdir.c
> + */
> +struct linux_dirent64;
> +
> +int vfs_getdents(struct file *file, struct linux_dirent64 __user *dirent,
> + unsigned int count);
> diff --git a/fs/readdir.c b/fs/readdir.c
> index 9c53edb60c03..1d541a6f2d55 100644
> --- a/fs/readdir.c
> +++ b/fs/readdir.c

(This needs an extra `#include "internal.h"`, missing declaration
warning reported privately by intel build robot... fs/ doesn't build
with W=1 by default; I'll resend v2 after some comments it doesn't make
much sense to spam patches at this point)

--
Dominique