From patchwork Thu Sep 24 16:39:10 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Goldwyn Rodrigues X-Patchwork-Id: 11797939 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1B12059D for ; Thu, 24 Sep 2020 16:39:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0A17D2395C for ; Thu, 24 Sep 2020 16:39:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728544AbgIXQjs (ORCPT ); Thu, 24 Sep 2020 12:39:48 -0400 Received: from mx2.suse.de ([195.135.220.15]:35914 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727074AbgIXQjr (ORCPT ); Thu, 24 Sep 2020 12:39:47 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id D9937B289; Thu, 24 Sep 2020 16:39:44 +0000 (UTC) From: Goldwyn Rodrigues To: linux-fsdevel@vger.kernel.org Cc: linux-btrfs@vger.kernel.org, david@fromorbit.com, hch@lst.de, johannes.thumshirn@wdc.com, dsterba@suse.com, darrick.wong@oracle.com, josef@toxicpanda.com, Goldwyn Rodrigues Subject: [PATCH 03/14] iomap: Allow filesystem to call iomap_dio_complete without i_rwsem Date: Thu, 24 Sep 2020 11:39:10 -0500 Message-Id: <20200924163922.2547-4-rgoldwyn@suse.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200924163922.2547-1-rgoldwyn@suse.de> References: <20200924163922.2547-1-rgoldwyn@suse.de> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org From: Christoph Hellwig This is to avoid the deadlock caused in btrfs because of O_DIRECT | O_DSYNC. Filesystems such as btrfs require i_rwsem while performing sync on a file. iomap_dio_rw() is called under i_rw_sem. This leads to a deadlock because of: iomap_dio_complete() generic_write_sync() btrfs_sync_file() Separate out iomap_dio_complete() from iomap_dio_rw(), so filesystems can call iomap_dio_complete() after unlocking i_rwsem. Signed-off-by: Christoph Hellwig Reviewed-by: Josef Bacik Signed-off-by: Goldwyn Rodrigues Reviewed-by: Darrick J. Wong --- fs/iomap/direct-io.c | 35 ++++++++++++++++++++++++++--------- include/linux/iomap.h | 5 +++++ 2 files changed, 31 insertions(+), 9 deletions(-) diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c index c1aafb2ab990..b88dbfe15118 100644 --- a/fs/iomap/direct-io.c +++ b/fs/iomap/direct-io.c @@ -76,7 +76,7 @@ static void iomap_dio_submit_bio(struct iomap_dio *dio, struct iomap *iomap, dio->submit.cookie = submit_bio(bio); } -static ssize_t iomap_dio_complete(struct iomap_dio *dio) +ssize_t iomap_dio_complete(struct iomap_dio *dio) { const struct iomap_dio_ops *dops = dio->dops; struct kiocb *iocb = dio->iocb; @@ -130,6 +130,7 @@ static ssize_t iomap_dio_complete(struct iomap_dio *dio) return ret; } +EXPORT_SYMBOL_GPL(iomap_dio_complete); static void iomap_dio_complete_work(struct work_struct *work) { @@ -406,8 +407,8 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length, * Returns -ENOTBLK In case of a page invalidation invalidation failure for * writes. The callers needs to fall back to buffered I/O in this case. */ -ssize_t -iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, +struct iomap_dio * +__iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, const struct iomap_ops *ops, const struct iomap_dio_ops *dops, bool wait_for_completion) { @@ -421,14 +422,14 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, struct iomap_dio *dio; if (!count) - return 0; + return NULL; if (WARN_ON(is_sync_kiocb(iocb) && !wait_for_completion)) - return -EIO; + return ERR_PTR(-EIO); dio = kmalloc(sizeof(*dio), GFP_KERNEL); if (!dio) - return -ENOMEM; + return ERR_PTR(-ENOMEM); dio->iocb = iocb; atomic_set(&dio->ref, 1); @@ -558,7 +559,7 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, dio->wait_for_completion = wait_for_completion; if (!atomic_dec_and_test(&dio->ref)) { if (!wait_for_completion) - return -EIOCBQUEUED; + return ERR_PTR(-EIOCBQUEUED); for (;;) { set_current_state(TASK_UNINTERRUPTIBLE); @@ -574,10 +575,26 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, __set_current_state(TASK_RUNNING); } - return iomap_dio_complete(dio); + return dio; out_free_dio: kfree(dio); - return ret; + if (ret) + return ERR_PTR(ret); + return NULL; +} +EXPORT_SYMBOL_GPL(__iomap_dio_rw); + +ssize_t +iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, + const struct iomap_ops *ops, const struct iomap_dio_ops *dops, + bool wait_for_completion) +{ + struct iomap_dio *dio; + + dio = __iomap_dio_rw(iocb, iter, ops, dops, wait_for_completion); + if (IS_ERR_OR_NULL(dio)) + return PTR_ERR_OR_ZERO(dio); + return iomap_dio_complete(dio); } EXPORT_SYMBOL_GPL(iomap_dio_rw); diff --git a/include/linux/iomap.h b/include/linux/iomap.h index 4d1d3c3469e9..172b3397a1a3 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -13,6 +13,7 @@ struct address_space; struct fiemap_extent_info; struct inode; +struct iomap_dio; struct iomap_writepage_ctx; struct iov_iter; struct kiocb; @@ -258,6 +259,10 @@ struct iomap_dio_ops { ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, const struct iomap_ops *ops, const struct iomap_dio_ops *dops, bool wait_for_completion); +struct iomap_dio *__iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, + const struct iomap_ops *ops, const struct iomap_dio_ops *dops, + bool wait_for_completion); +ssize_t iomap_dio_complete(struct iomap_dio *dio); int iomap_dio_iopoll(struct kiocb *kiocb, bool spin); #ifdef CONFIG_SWAP