io_uring: io_uring: add support for async work inheriting files

This is in preparation for adding opcodes that need to add new files
in a process file table, system calls like open(2) or accept4(2).

If an opcode needs this, it must set IO_WQ_WORK_NEEDS_FILES in the work
item. If work that needs to get punted to async context have this
set, the async worker will assume the original task file table before
executing the work.

Note that opcodes that need access to the current files of an
application cannot be done through IORING_SETUP_SQPOLL.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/io-wq.h b/fs/io-wq.h
index be8f22c8937b..e93f764b1fa4 100644
--- a/fs/io-wq.h
+++ b/fs/io-wq.h
@@ -8,6 +8,7 @@ enum {
 	IO_WQ_WORK_HAS_MM	= 2,
 	IO_WQ_WORK_HASHED	= 4,
 	IO_WQ_WORK_NEEDS_USER	= 8,
+	IO_WQ_WORK_NEEDS_FILES	= 16,
 
 	IO_WQ_HASH_SHIFT	= 24,	/* upper 8 bits are used for hash key */
 };
@@ -22,12 +23,14 @@ struct io_wq_work {
 	struct list_head list;
 	void (*func)(struct io_wq_work **);
 	unsigned flags;
+	struct files_struct *files;
 };
 
 #define INIT_IO_WORK(work, _func)			\
 	do {						\
 		(work)->func = _func;			\
 		(work)->flags = 0;			\
+		(work)->files = NULL;			\
 	} while (0)					\
 
 struct io_wq *io_wq_create(unsigned concurrency, struct mm_struct *mm);