[PATCH] io_uring: honor original task RLIMIT_FSIZE

[Jens Axboe <axboe@kernel.dk>]

With the previous fixes for number of files open checking, I added
some debug code to see if we had other spots where we're checking
rlimit() against the async io-wq workers. The only one I found was
file size checking, which we should also honor.

During write prep, store the max file size and override that for
the current ask if we're in io-wq worker context.

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

---

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 731a91b772a3..cdc4216a164f 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -606,7 +606,10 @@ struct io_kiocb {
 	struct list_head	list;
 	unsigned int		flags;
 	refcount_t		refs;
-	struct task_struct	*task;
+	union {
+		struct task_struct	*task;
+		unsigned long		fsize;
+	};
 	u64			user_data;
 	u32			result;
 	u32			sequence;
@@ -2596,6 +2599,8 @@ static int io_write_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 	if (unlikely(!(req->file->f_mode & FMODE_WRITE)))
 		return -EBADF;
 
+	req->fsize = rlimit(RLIMIT_FSIZE);
+
 	/* either don't need iovec imported or already have it */
 	if (!req->io || req->flags & REQ_F_NEED_CLEANUP)
 		return 0;
@@ -2665,10 +2670,17 @@ static int io_write(struct io_kiocb *req, bool force_nonblock)
 		}
 		kiocb->ki_flags |= IOCB_WRITE;
 
+		if (!force_nonblock)
+			current->signal->rlim[RLIMIT_FSIZE].rlim_cur = req->fsize;
+
 		if (req->file->f_op->write_iter)
 			ret2 = call_write_iter(req->file, kiocb, &iter);
 		else
 			ret2 = loop_rw_iter(WRITE, req->file, kiocb, &iter);
+
+		if (!force_nonblock)
+			current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
+
 		/*
 		 * Raw bdev writes will -EOPNOTSUPP for IOCB_NOWAIT. Just
 		 * retry them without IOCB_NOWAIT.

-- 
Jens Axboe