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

[Stefan Roesch <shr@fb.com>]

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;
>  }
>  
>