[PATCH v8 10/11] io_uring: add support for IORING_OP_SYMLINKAT

Dmitry Kadashev
2021-07-07T12:28:21Z

IORING_OP_SYMLINKAT behaves like symlinkat(2) and takes the same flags
and arguments.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Suggested-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/io-uring/20210514145259.wtl4xcsp52woi6ab@wittgenstein/
Signed-off-by: Dmitry Kadashev <dkadashev@gmail.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
---
fs/internal.h | 1 +
fs/io_uring.c | 66 +++++++++++++++++++++++++++++++++++
fs/namei.c | 3 +-
include/uapi/linux/io_uring.h | 1 +
4 files changed, 69 insertions(+), 2 deletions(-)

diff --git a/fs/internal.h b/fs/internal.h
index 207a455e32d3..3b3954214385 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -78,6 +78,7 @@ int may_linkat(struct user_namespace *mnt_userns, struct path *link);
int do_renameat2(int olddfd, struct filename *oldname, int newdfd,
struct filename *newname, unsigned int flags);
int do_mkdirat(int dfd, struct filename *name, umode_t mode);
+int do_symlinkat(struct filename *from, int newdfd, struct filename *to);

/*
* namespace.c
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 42d54f9bbbb2..a0f681ec25bb 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -681,6 +681,13 @@ struct io_mkdir {
struct filename *filename;
};

+struct io_symlink {
+ struct file *file;
+ int new_dfd;
+ struct filename *oldpath;
+ struct filename *newpath;
+};
+
struct io_completion {
struct file *file;
struct list_head list;
@@ -839,6 +846,7 @@ struct io_kiocb {
struct io_rename rename;
struct io_unlink unlink;
struct io_mkdir mkdir;
+ struct io_symlink symlink;
/* use only after cleaning per-op data, see io_clean_op() */
struct io_completion compl;
};
@@ -1051,6 +1059,7 @@ static const struct io_op_def io_op_defs[] = {
[IORING_OP_RENAMEAT] = {},
[IORING_OP_UNLINKAT] = {},
[IORING_OP_MKDIRAT] = {},
+ [IORING_OP_SYMLINKAT] = {},
};

static bool io_disarm_next(struct io_kiocb *req);
@@ -3596,6 +3605,54 @@ static int io_mkdirat(struct io_kiocb *req, int issue_flags)
return 0;
}

+static int io_symlinkat_prep(struct io_kiocb *req,
+ const struct io_uring_sqe *sqe)
+{
+ struct io_symlink *sl = &req->symlink;
+ const char __user *oldpath, *newpath;
+
+ if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+ return -EINVAL;
+ if (sqe->ioprio || sqe->len || sqe->rw_flags || sqe->buf_index)
+ return -EINVAL;
+ if (unlikely(req->flags & REQ_F_FIXED_FILE))
+ return -EBADF;
+
+ sl->new_dfd = READ_ONCE(sqe->fd);
+ oldpath = u64_to_user_ptr(READ_ONCE(sqe->addr));
+ newpath = u64_to_user_ptr(READ_ONCE(sqe->addr2));
+
+ sl->oldpath = getname(oldpath);
+ if (IS_ERR(sl->oldpath))
+ return PTR_ERR(sl->oldpath);
+
+ sl->newpath = getname(newpath);
+ if (IS_ERR(sl->newpath)) {
+ putname(sl->oldpath);
+ return PTR_ERR(sl->newpath);
+ }
+
+ req->flags |= REQ_F_NEED_CLEANUP;
+ return 0;
+}
+
+static int io_symlinkat(struct io_kiocb *req, int issue_flags)
+{
+ struct io_symlink *sl = &req->symlink;
+ int ret;
+
+ if (issue_flags & IO_URING_F_NONBLOCK)
+ return -EAGAIN;
+
+ ret = do_symlinkat(sl->oldpath, sl->new_dfd, sl->newpath);
+
+ req->flags &= ~REQ_F_NEED_CLEANUP;
+ if (ret < 0)
+ req_set_fail(req);
+ io_req_complete(req, ret);
+ return 0;
+}
+
static int io_shutdown_prep(struct io_kiocb *req,
const struct io_uring_sqe *sqe)
{
@@ -6006,6 +6063,8 @@ static int io_req_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
return io_unlinkat_prep(req, sqe);
case IORING_OP_MKDIRAT:
return io_mkdirat_prep(req, sqe);
+ case IORING_OP_SYMLINKAT:
+ return io_symlinkat_prep(req, sqe);
}

printk_once(KERN_WARNING "io_uring: unhandled opcode %d\n",
@@ -6170,6 +6229,10 @@ static void io_clean_op(struct io_kiocb *req)
case IORING_OP_MKDIRAT:
putname(req->mkdir.filename);
break;
+ case IORING_OP_SYMLINKAT:
+ putname(req->symlink.oldpath);
+ putname(req->symlink.newpath);
+ break;
}
}
if ((req->flags & REQ_F_POLLED) && req->apoll) {
@@ -6301,6 +6364,9 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
case IORING_OP_MKDIRAT:
ret = io_mkdirat(req, issue_flags);
break;
+ case IORING_OP_SYMLINKAT:
+ ret = io_symlinkat(req, issue_flags);
+ break;
default:
ret = -EINVAL;
break;
diff --git a/fs/namei.c b/fs/namei.c
index d06aeaf5da00..f241348e64f4 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4213,8 +4213,7 @@ int vfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
}
EXPORT_SYMBOL(vfs_symlink);

-static int do_symlinkat(struct filename *from, int newdfd,
- struct filename *to)
+int do_symlinkat(struct filename *from, int newdfd, struct filename *to)
{
int error;
struct dentry *dentry;
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index a926407c230e..61fd347ab176 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -134,6 +134,7 @@ enum {
IORING_OP_RENAMEAT,
IORING_OP_UNLINKAT,
IORING_OP_MKDIRAT,
+ IORING_OP_SYMLINKAT,

/* this goes last, obviously */
IORING_OP_LAST,
--
2.30.2