Re: [PATCH v2 1/6] aio: take list removal to (some) callers of aio_complete()

[Christoph Hellwig <hch@lst.de>]

On Mon, May 28, 2018 at 06:57:02PM +0100, Al Viro wrote:
> From: Al Viro <viro@zeniv.linux.org.uk>
> 
> We really want iocb out of io_cancel(2) reach before we start tearing
> it down.

A little helper would be useful, better naming for it welcome:

diff --git a/fs/aio.c b/fs/aio.c
index f95b167801c2..ae5977563b7e 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1390,18 +1390,22 @@ SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
 	return -EINVAL;
 }
 
+static void aio_remove_iocb(struct aio_kiocb *iocb)
+{
+	struct kioctx *ctx = iocb->ki_ctx;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctx->ctx_lock, flags);
+	list_del(&iocb->ki_list);
+	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
+}
+
 static void aio_complete_rw(struct kiocb *kiocb, long res, long res2)
 {
 	struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, rw);
 
-	if (!list_empty_careful(&iocb->ki_list)) {
-		struct kioctx	*ctx = iocb->ki_ctx;
-		unsigned long flags;
-
-		spin_lock_irqsave(&ctx->ctx_lock, flags);
-		list_del(&iocb->ki_list);
-		spin_unlock_irqrestore(&ctx->ctx_lock, flags);
-	}
+	if (!list_empty_careful(&iocb->ki_list))
+		aio_remove_iocb(iocb);
 
 	if (kiocb->ki_flags & IOCB_WRITE) {
 		struct inode *inode = file_inode(kiocb->ki_filp);
@@ -1605,15 +1609,8 @@ static void aio_poll_work(struct work_struct *work)
 {
 	struct aio_kiocb *iocb = container_of(work, struct aio_kiocb, poll.work);
 
-	if (!list_empty_careful(&iocb->ki_list)) {
-		struct kioctx	*ctx = iocb->ki_ctx;
-		unsigned long flags;
-
-		spin_lock_irqsave(&ctx->ctx_lock, flags);
-		list_del(&iocb->ki_list);
-		spin_unlock_irqrestore(&ctx->ctx_lock, flags);
-	}
-
+	if (!list_empty_careful(&iocb->ki_list))
+		aio_remove_iocb(iocb);
 	__aio_poll_complete(iocb, iocb->poll.events);
 }