[PATCH 2/5] io_uring: add unlink opcode for current working directory

[Usama Arif <usama.arif@bytedance.com>]

This provides consistency between io_uring and the respective I/O syscall
and avoids having the user of liburing specify the cwd in sqe for
IORING_OP_UNLINKAT.

Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
 fs/io_uring.c                 | 22 ++++++++++++++++------
 include/uapi/linux/io_uring.h |  1 +
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 8bf56523ff7f..d38c5f54f6a4 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1308,6 +1308,7 @@ static const struct io_op_def io_op_defs[] = {
 	},
 	[IORING_OP_RENAME] = {},
 	[IORING_OP_RENAMEAT] = {},
+	[IORING_OP_UNLINK] = {},
 	[IORING_OP_UNLINKAT] = {},
 	[IORING_OP_MKDIRAT] = {},
 	[IORING_OP_SYMLINKAT] = {},
@@ -1454,6 +1455,8 @@ const char *io_uring_get_opcode(u8 opcode)
 		return "RENAME";
 	case IORING_OP_RENAMEAT:
 		return "RENAMEAT";
+	case IORING_OP_UNLINK:
+		return "UNLINK";
 	case IORING_OP_UNLINKAT:
 		return "UNLINKAT";
 	case IORING_OP_MKDIRAT:
@@ -4847,8 +4850,8 @@ static int io_setxattr(struct io_kiocb *req, unsigned int issue_flags)
 	return 0;
 }
 
-static int io_unlinkat_prep(struct io_kiocb *req,
-			    const struct io_uring_sqe *sqe)
+static int io_unlink_prep(struct io_kiocb *req,
+			    const struct io_uring_sqe *sqe, bool is_cwd)
 {
 	struct io_unlink *un = &req->unlink;
 	const char __user *fname;
@@ -4858,7 +4861,10 @@ static int io_unlinkat_prep(struct io_kiocb *req,
 	if (unlikely(req->flags & REQ_F_FIXED_FILE))
 		return -EBADF;
 
-	un->dfd = READ_ONCE(sqe->fd);
+	if (is_cwd)
+		un->dfd = AT_FDCWD;
+	else
+		un->dfd = READ_ONCE(sqe->fd);
 
 	un->flags = READ_ONCE(sqe->unlink_flags);
 	if (un->flags & ~AT_REMOVEDIR)
@@ -4873,7 +4879,7 @@ static int io_unlinkat_prep(struct io_kiocb *req,
 	return 0;
 }
 
-static int io_unlinkat(struct io_kiocb *req, unsigned int issue_flags)
+static int io_unlink(struct io_kiocb *req, unsigned int issue_flags)
 {
 	struct io_unlink *un = &req->unlink;
 	int ret;
@@ -8087,8 +8093,10 @@ static int io_req_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		return io_rename_prep(req, sqe, 1);
 	case IORING_OP_RENAMEAT:
 		return io_rename_prep(req, sqe, 0);
+	case IORING_OP_UNLINK:
+		return io_unlink_prep(req, sqe, 1);
 	case IORING_OP_UNLINKAT:
-		return io_unlinkat_prep(req, sqe);
+		return io_unlink_prep(req, sqe, 0);
 	case IORING_OP_MKDIRAT:
 		return io_mkdirat_prep(req, sqe);
 	case IORING_OP_SYMLINKAT:
@@ -8243,6 +8251,7 @@ static void io_clean_op(struct io_kiocb *req)
 			putname(req->rename.oldpath);
 			putname(req->rename.newpath);
 			break;
+		case IORING_OP_UNLINK:
 		case IORING_OP_UNLINKAT:
 			putname(req->unlink.filename);
 			break;
@@ -8409,8 +8418,9 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
 	case IORING_OP_RENAMEAT:
 		ret = io_rename(req, issue_flags);
 		break;
+	case IORING_OP_UNLINK:
 	case IORING_OP_UNLINKAT:
-		ret = io_unlinkat(req, issue_flags);
+		ret = io_unlink(req, issue_flags);
 		break;
 	case IORING_OP_MKDIRAT:
 		ret = io_mkdirat(req, issue_flags);
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 73f4e1c4133d..7828b7183d01 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -190,6 +190,7 @@ enum io_uring_op {
 	IORING_OP_SOCKET,
 	IORING_OP_URING_CMD,
 	IORING_OP_RENAME,
+	IORING_OP_UNLINK,
 
 	/* this goes last, obviously */
 	IORING_OP_LAST,
-- 
2.25.1