From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-3333851-1521617622-2-2591345764960405203 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.25, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES unknown, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='CN', FromHeader='de', MailFrom='org' X-Spam-charsets: X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: linux-api-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1521617621; b=ucoBlv1NJWJaxyGNAp2DVfsx+DRXyKIe92tdUMqHQyJQ5+c 4n0uSgxYc7+DYGV6hMC8zvTKxMgtqdKAloA4H2Vrleqs5cO2HQpEpsq4/6xqfRqw TaCxqbm98X6SEKWCkmb5dgTOcxghA34kYdGiso+bL2as7EQxinWFr9wZ1l+jLQLa IgBUlXL0k6FhzfLa3GSyaE5PgMdxv8gzs8cTpDKEeZ62YLOd6fdbsUe4DxiVkrn9 97We/YRnMJZsb5CBItwbWBBDCw+nox/nb6M7UxqapaPmV1NBHbKMnLrMDyUlnHzv LGuKJAhiLi+2Mbd1aVoSVmCn7OK/M4Nsx9K8A/Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:sender:list-id; s=arctest; t=1521617621; bh=Kg+Hy36NtWjy1Av6TXTZg3S8v3wKqgMPuAYVu1ScJs4=; b=I1W7Mc84UaXV RJnrpbdga7Hbb6RivaY1EhoazkNHExv0gNNQKqtqwhcPtN7OZpt2ZzP9TGtMZQXm APHPuAqjqh+xh1iqBegClnFSoEbcCwtUW4c4So2BGRcwAJSlVi0Wha8GhE/BX/RF Wn/yyjkO18XdIttMck0IEL1BGA/0el3fGkxH635sGum1BI/3VPoLhfrEBH9nbkb4 kgIyP8ts6yBm7+Yy9hcUMh9wLXCx1yrU1nP+924bfYOqEd3SuQhVE5xZwiwmCg9y H8RQXA3IqL06/ADs3dt2Z9rf8DQDJd980UGd6RVfS2AkSyuMsV0GWDQbcerSJVCW x5ixe+l6+Q== ARC-Authentication-Results: i=1; mx4.messagingengine.com; arc=none (no signatures found); dkim=fail (message has been altered, 2048-bit rsa key sha256) header.d=infradead.org header.i=@infradead.org header.b=uYK5iTLL x-bits=2048 x-keytype=rsa x-algorithm=sha256 x-selector=bombadil.20170209; dmarc=none (p=none,has-list-id=yes,d=none) header.from=lst.de; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-api-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=lst.de header.result=pass header_is_org_domain=yes; x-vs=clean score=0 state=0 Authentication-Results: mx4.messagingengine.com; arc=none (no signatures found); dkim=fail (message has been altered, 2048-bit rsa key sha256) header.d=infradead.org header.i=@infradead.org header.b=uYK5iTLL x-bits=2048 x-keytype=rsa x-algorithm=sha256 x-selector=bombadil.20170209; dmarc=none (p=none,has-list-id=yes,d=none) header.from=lst.de; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-api-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=lst.de header.result=pass header_is_org_domain=yes; x-vs=clean score=0 state=0 X-ME-VSCategory: clean Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751595AbeCUHdK (ORCPT ); Wed, 21 Mar 2018 03:33:10 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:46706 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751798AbeCUHdF (ORCPT ); Wed, 21 Mar 2018 03:33:05 -0400 From: Christoph Hellwig To: viro@zeniv.linux.org.uk Cc: Avi Kivity , linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 7/9] aio: add delayed cancel support Date: Wed, 21 Mar 2018 08:32:30 +0100 Message-Id: <20180321073232.13366-8-hch@lst.de> X-Mailer: git-send-email 2.14.2 In-Reply-To: <20180321073232.13366-1-hch@lst.de> References: <20180321073232.13366-1-hch@lst.de> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-api-owner@vger.kernel.org X-Mailing-List: linux-api@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: The upcoming aio poll support would like to be able to complete the iocb inline from the cancellation context, but that would cause a lock order reversal. Add support for optionally moving the cancelation outside the context lock to avoid this reversal. Signed-off-by: Christoph Hellwig Acked-by: Jeff Moyer --- fs/aio.c | 49 ++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 38 insertions(+), 11 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 0b6394b4e528..9d7d6e4cde87 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -170,6 +170,10 @@ struct aio_kiocb { struct list_head ki_list; /* the aio core uses this * for cancellation */ + unsigned int flags; /* protected by ctx->ctx_lock */ +#define AIO_IOCB_DELAYED_CANCEL (1 << 0) +#define AIO_IOCB_CANCELLED (1 << 1) + /* * If the aio_resfd field of the userspace iocb is not zero, * this is the underlying eventfd context to deliver events to. @@ -536,9 +540,9 @@ static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events) #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event)) #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE) -void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel) +static void __kiocb_set_cancel_fn(struct aio_kiocb *req, + kiocb_cancel_fn *cancel, unsigned int iocb_flags) { - struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, rw); struct kioctx *ctx = req->ki_ctx; unsigned long flags; @@ -548,8 +552,15 @@ void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel) spin_lock_irqsave(&ctx->ctx_lock, flags); list_add_tail(&req->ki_list, &ctx->active_reqs); req->ki_cancel = cancel; + req->flags |= iocb_flags; spin_unlock_irqrestore(&ctx->ctx_lock, flags); } + +void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel) +{ + return __kiocb_set_cancel_fn(container_of(iocb, struct aio_kiocb, rw), + cancel, 0); +} EXPORT_SYMBOL(kiocb_set_cancel_fn); /* @@ -603,17 +614,27 @@ static void free_ioctx_users(struct percpu_ref *ref) { struct kioctx *ctx = container_of(ref, struct kioctx, users); struct aio_kiocb *req; + LIST_HEAD(list); spin_lock_irq(&ctx->ctx_lock); - while (!list_empty(&ctx->active_reqs)) { req = list_first_entry(&ctx->active_reqs, struct aio_kiocb, ki_list); - kiocb_cancel(req); - } + if (req->flags & AIO_IOCB_DELAYED_CANCEL) { + req->flags |= AIO_IOCB_CANCELLED; + list_move_tail(&req->ki_list, &list); + } else { + kiocb_cancel(req); + } + } spin_unlock_irq(&ctx->ctx_lock); + while (!list_empty(&list)) { + req = list_first_entry(&list, struct aio_kiocb, ki_list); + kiocb_cancel(req); + } + percpu_ref_kill(&ctx->reqs); percpu_ref_put(&ctx->reqs); } @@ -1785,15 +1806,22 @@ SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb, if (unlikely(!ctx)) return -EINVAL; - spin_lock_irq(&ctx->ctx_lock); + ret = -EINVAL; + spin_lock_irq(&ctx->ctx_lock); kiocb = lookup_kiocb(ctx, iocb, key); + if (kiocb) { + if (kiocb->flags & AIO_IOCB_DELAYED_CANCEL) { + kiocb->flags |= AIO_IOCB_CANCELLED; + } else { + ret = kiocb_cancel(kiocb); + kiocb = NULL; + } + } + spin_unlock_irq(&ctx->ctx_lock); + if (kiocb) ret = kiocb_cancel(kiocb); - else - ret = -EINVAL; - - spin_unlock_irq(&ctx->ctx_lock); if (!ret) { /* @@ -1805,7 +1833,6 @@ SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb, } percpu_ref_put(&ctx->users); - return ret; } -- 2.14.2