io_uring: add helpers to decode the fixed file file_ptr

Remove all the open coded magic on slot->file_ptr by introducing two
helpers that return the file pointer and the flags instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230620113235.920399-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Christoph Hellwig

io_uring/filetable.c

@@ -78,10 +78,8 @@ static int io_install_fixed_file(struct io_ring_ctx *ctx, struct file *file,
 	file_slot = io_fixed_file_slot(&ctx->file_table, slot_index);
 
 	if (file_slot->file_ptr) {
-		struct file *old_file;
-
-		old_file = (struct file *)(file_slot->file_ptr & FFS_MASK);
-		ret = io_queue_rsrc_removal(ctx->file_data, slot_index, old_file);
+		ret = io_queue_rsrc_removal(ctx->file_data, slot_index,
+					    io_slot_file(file_slot));
 		if (ret)
 			return ret;
 
@@ -140,7 +138,6 @@ int io_fixed_fd_install(struct io_kiocb *req, unsigned int issue_flags,
 int io_fixed_fd_remove(struct io_ring_ctx *ctx, unsigned int offset)
 {
 	struct io_fixed_file *file_slot;
-	struct file *file;
 	int ret;
 
 	if (unlikely(!ctx->file_data))
@@ -153,8 +150,8 @@ int io_fixed_fd_remove(struct io_ring_ctx *ctx, unsigned int offset)
 	if (!file_slot->file_ptr)
 		return -EBADF;
 
-	file = (struct file *)(file_slot->file_ptr & FFS_MASK);
-	ret = io_queue_rsrc_removal(ctx->file_data, offset, file);
+	ret = io_queue_rsrc_removal(ctx->file_data, offset,
+				    io_slot_file(file_slot));
 	if (ret)
 		return ret;
 

io_uring/filetable.h

@@ -5,10 +5,6 @@
 #include <linux/file.h>
 #include <linux/io_uring_types.h>
 
-#define FFS_NOWAIT		0x1UL
-#define FFS_ISREG		0x2UL
-#define FFS_MASK		~(FFS_NOWAIT|FFS_ISREG)
-
 bool io_alloc_file_tables(struct io_file_table *table, unsigned nr_files);
 void io_free_file_tables(struct io_file_table *table);
 
@@ -43,12 +39,24 @@ io_fixed_file_slot(struct io_file_table *table, unsigned i)
 	return &table->files[i];
 }
 
+#define FFS_NOWAIT		0x1UL
+#define FFS_ISREG		0x2UL
+#define FFS_MASK		~(FFS_NOWAIT|FFS_ISREG)
+
+static inline unsigned int io_slot_flags(struct io_fixed_file *slot)
+{
+	return (slot->file_ptr & ~FFS_MASK) << REQ_F_SUPPORT_NOWAIT_BIT;
+}
+
+static inline struct file *io_slot_file(struct io_fixed_file *slot)
+{
+	return (struct file *)(slot->file_ptr & FFS_MASK);
+}
+
 static inline struct file *io_file_from_index(struct io_file_table *table,
 					      int index)
 {
-	struct io_fixed_file *slot = io_fixed_file_slot(table, index);
-
-	return (struct file *) (slot->file_ptr & FFS_MASK);
+	return io_slot_file(io_fixed_file_slot(table, index));
 }
 
 static inline void io_fixed_file_set(struct io_fixed_file *file_slot,

io_uring/io_uring.c

@@ -2028,19 +2028,17 @@ inline struct file *io_file_get_fixed(struct io_kiocb *req, int fd,
 				      unsigned int issue_flags)
 {
 	struct io_ring_ctx *ctx = req->ctx;
+	struct io_fixed_file *slot;
 	struct file *file = NULL;
-	unsigned long file_ptr;
 
 	io_ring_submit_lock(ctx, issue_flags);
 
 	if (unlikely((unsigned int)fd >= ctx->nr_user_files))
 		goto out;
 	fd = array_index_nospec(fd, ctx->nr_user_files);
-	file_ptr = io_fixed_file_slot(&ctx->file_table, fd)->file_ptr;
-	file = (struct file *) (file_ptr & FFS_MASK);
-	file_ptr &= ~FFS_MASK;
-	/* mask in overlapping REQ_F and FFS bits */
-	req->flags |= (file_ptr << REQ_F_SUPPORT_NOWAIT_BIT);
+	slot = io_fixed_file_slot(&ctx->file_table, fd);
+	file = io_slot_file(slot);
+	req->flags |= io_slot_flags(slot);
 	io_req_set_rsrc_node(req, ctx, 0);
 out:
 	io_ring_submit_unlock(ctx, issue_flags);

io_uring/rsrc.c

@@ -354,7 +354,6 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
 	__s32 __user *fds = u64_to_user_ptr(up->data);
 	struct io_rsrc_data *data = ctx->file_data;
 	struct io_fixed_file *file_slot;
-	struct file *file;
 	int fd, i, err = 0;
 	unsigned int done;
 
@@ -382,15 +381,16 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
 		file_slot = io_fixed_file_slot(&ctx->file_table, i);
 
 		if (file_slot->file_ptr) {
-			file = (struct file *)(file_slot->file_ptr & FFS_MASK);
-			err = io_queue_rsrc_removal(data, i, file);
+			err = io_queue_rsrc_removal(data, i,
+						    io_slot_file(file_slot));
 			if (err)
 				break;
 			file_slot->file_ptr = 0;
 			io_file_bitmap_clear(&ctx->file_table, i);
 		}
 		if (fd != -1) {
-			file = fget(fd);
+			struct file *file = fget(fd);
+
 			if (!file) {
 				err = -EBADF;
 				break;