Re: [PATCH v9 4/5] io_uring: add fsetxattr and setxattr support

Christian Brauner
2021-12-29T14:52:06Z

On Tue, Dec 28, 2021 at 10:41:44AM -0800, Stefan Roesch wrote:
> This adds support to io_uring for the fsetxattr and setxattr API.
>
> Signed-off-by: Stefan Roesch <shr@fb.com>
> ---
> fs/io_uring.c | 165 ++++++++++++++++++++++++++++++++++
> include/uapi/linux/io_uring.h | 6 +-
> 2 files changed, 170 insertions(+), 1 deletion(-)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index c8258c784116..2a0138a2876a 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -82,6 +82,7 @@
> #include <linux/audit.h>
> #include <linux/security.h>
> #include <linux/atomic-ref.h>
> +#include <linux/xattr.h>
>
> #define CREATE_TRACE_POINTS
> #include <trace/events/io_uring.h>
> @@ -726,6 +727,12 @@ struct io_async_rw {
> struct wait_page_queue wpq;
> };
>
> +struct io_xattr {
> + struct file *file;
> + struct xattr_ctx ctx;
> + struct filename *filename;
> +};
> +
> enum {
> REQ_F_FIXED_FILE_BIT = IOSQE_FIXED_FILE_BIT,
> REQ_F_IO_DRAIN_BIT = IOSQE_IO_DRAIN_BIT,
> @@ -866,6 +873,7 @@ struct io_kiocb {
> struct io_symlink symlink;
> struct io_hardlink hardlink;
> struct io_getdents getdents;
> + struct io_xattr xattr;
> };
>
> u8 opcode;
> @@ -1118,6 +1126,10 @@ static const struct io_op_def io_op_defs[] = {
> [IORING_OP_GETDENTS] = {
> .needs_file = 1,
> },
> + [IORING_OP_FSETXATTR] = {
> + .needs_file = 1
> + },
> + [IORING_OP_SETXATTR] = {},
> };
>
> /* requests with any of those set should undergo io_disarm_next() */
> @@ -3887,6 +3899,140 @@ static int io_renameat(struct io_kiocb *req, unsigned int issue_flags)
> return 0;
> }
>
> +static int __io_setxattr_prep(struct io_kiocb *req,
> + const struct io_uring_sqe *sqe)
> +{
> + struct io_xattr *ix = &req->xattr;
> + const char __user *name;
> + int ret;
> +
> + if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
> + return -EINVAL;
> + if (unlikely(sqe->ioprio))
> + return -EINVAL;
> + if (unlikely(req->flags & REQ_F_FIXED_FILE))
> + return -EBADF;
> +
> + ix->filename = NULL;
> + name = u64_to_user_ptr(READ_ONCE(sqe->addr));
> + ix->ctx.value = u64_to_user_ptr(READ_ONCE(sqe->addr2));
> + ix->ctx.kvalue = NULL;
> + ix->ctx.size = READ_ONCE(sqe->len);
> + ix->ctx.flags = READ_ONCE(sqe->xattr_flags);
> +
> + ix->ctx.kname = kmalloc(sizeof(*ix->ctx.kname), GFP_KERNEL);
> + if (!ix->ctx.kname)
> + return -ENOMEM;
> +
> + ret = setxattr_copy(name, &ix->ctx);
> + if (ret) {
> + kfree(ix->ctx.kname);
> + return ret;
> + }
> +
> + req->flags |= REQ_F_NEED_CLEANUP;
> + return 0;
> +}
> +
> +static int io_setxattr_prep(struct io_kiocb *req,
> + const struct io_uring_sqe *sqe)
> +{
> + struct io_xattr *ix = &req->xattr;
> + const char __user *path;
> + int ret;
> +
> + ret = __io_setxattr_prep(req, sqe);
> + if (ret)
> + return ret;
> +
> + path = u64_to_user_ptr(READ_ONCE(sqe->addr3));
> +
> + ix->filename = getname_flags(path, LOOKUP_FOLLOW, NULL);
> + if (IS_ERR(ix->filename)) {
> + ret = PTR_ERR(ix->filename);
> + ix->filename = NULL;
> + }
> +
> + return ret;
> +}
> +
> +static int io_fsetxattr_prep(struct io_kiocb *req,
> + const struct io_uring_sqe *sqe)
> +{
> + return __io_setxattr_prep(req, sqe);
> +}
> +
> +static int __io_setxattr(struct io_kiocb *req, unsigned int issue_flags,
> + struct path *path)
> +{
> + struct io_xattr *ix = &req->xattr;
> + int ret;
> +
> + ret = mnt_want_write(path->mnt);
> + if (!ret) {
> + ret = do_setxattr(mnt_user_ns(path->mnt), path->dentry, &ix->ctx);
> + mnt_drop_write(path->mnt);
> + }
> +
> + return ret;
> +}
> +
> +static int io_fsetxattr(struct io_kiocb *req, unsigned int issue_flags)
> +{
> + struct io_xattr *ix = &req->xattr;
> + int ret;
> +
> + if (issue_flags & IO_URING_F_NONBLOCK)
> + return -EAGAIN;
> +
> + ret = __io_setxattr(req, issue_flags, &req->file->f_path);
> +
> + req->flags &= ~REQ_F_NEED_CLEANUP;
> + kfree(ix->ctx.kname);
> +
> + if (ix->ctx.kvalue)
> + kvfree(ix->ctx.kvalue);
> + if (ret < 0)
> + req_set_fail(req);
> +
> + io_req_complete(req, ret);
> + return 0;
> +}
> +
> +static int io_setxattr(struct io_kiocb *req, unsigned int issue_flags)
> +{
> + struct io_xattr *ix = &req->xattr;
> + unsigned int lookup_flags = LOOKUP_FOLLOW;
> + struct path path;
> + int ret;
> +
> + if (issue_flags & IO_URING_F_NONBLOCK)
> + return -EAGAIN;
> +
> +retry:
> + ret = do_user_path_at_empty(AT_FDCWD, ix->filename, lookup_flags, &path);
> + if (!ret) {
> + ret = __io_setxattr(req, issue_flags, &path);
> + path_put(&path);
> + if (retry_estale(ret, lookup_flags)) {
> + lookup_flags |= LOOKUP_REVAL;
> + goto retry;
> + }
> + }
> + putname(ix->filename);
> +
> + req->flags &= ~REQ_F_NEED_CLEANUP;
> + kfree(ix->ctx.kname);
> +
> + if (ix->ctx.kvalue)
> + kvfree(ix->ctx.kvalue);
> + if (ret < 0)
> + req_set_fail(req);
> +
> + io_req_complete(req, ret);
> + return 0;
> +}

(One suggestin below.)

Looks good,
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>

You could minimize the redudancy by implementing a simple helper
callable from both io_fsetxattr() and io_setxattr() if you think it's
worth with. So sm like:

From 2f837aa2a19b5cd8e73fffb9b87b6e6b22c5cae7 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brauner@ubuntu.com>
Date: Wed, 29 Dec 2021 15:22:34 +0100
Subject: [PATCH] UNTESTED

---
fs/io_uring.c | 36 +++++++++++++++++-------------------
1 file changed, 17 insertions(+), 19 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 7204b8d593e4..c88916b8cccc 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4118,6 +4118,21 @@ static int __io_setxattr(struct io_kiocb *req, unsigned int issue_flags,
return ret;
}

+static void __io_setxattr_finish(struct io_kiocb *req, int ret)
+{
+ struct xattr_ctx *ctx = &req->xattr.ctx;
+
+ req->flags &= ~REQ_F_NEED_CLEANUP;
+
+ kfree(ctx->kname);
+ if (ctx->kvalue)
+ kvfree(ctx->kvalue);
+
+ if (ret < 0)
+ req_set_fail(req);
+
+ io_req_complete(req, ret);
+}
+
static int io_fsetxattr(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_xattr *ix = &req->xattr;
@@ -4127,16 +4142,7 @@ static int io_fsetxattr(struct io_kiocb *req, unsigned int issue_flags)
return -EAGAIN;

ret = __io_setxattr(req, issue_flags, &req->file->f_path);
-
- req->flags &= ~REQ_F_NEED_CLEANUP;
- kfree(ix->ctx.kname);
-
- if (ix->ctx.kvalue)
- kvfree(ix->ctx.kvalue);
- if (ret < 0)
- req_set_fail(req);
-
- io_req_complete(req, ret);
+ __io_setxattr_finish(req, ret);
return 0;
}

@@ -4162,15 +4168,7 @@ static int io_setxattr(struct io_kiocb *req, unsigned int issue_flags)
}
putname(ix->filename);

- req->flags &= ~REQ_F_NEED_CLEANUP;
- kfree(ix->ctx.kname);
-
- if (ix->ctx.kvalue)
- kvfree(ix->ctx.kvalue);
- if (ret < 0)
- req_set_fail(req);
-
- io_req_complete(req, ret);
+ __io_setxattr_finish(req, ret);
return 0;
}

--
2.30.2