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

Stefan Roesch
2021-12-29T20:35:33Z

On 12/29/21 6:51 AM, Christian Brauner wrote:
> 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
>

I added the helper function. I made a similar change for the get case.

> ---
> 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;
> }
>
>