From patchwork Wed Apr 1 18:56:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Trond Myklebust X-Patchwork-Id: 11469467 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 66DCD1805 for ; Wed, 1 Apr 2020 18:59:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 45C8620784 for ; Wed, 1 Apr 2020 18:59:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585767547; bh=MKetfRiAoJ6gMAtmHOaUq82VqNYGDdavL/eLNN/n6FM=; h=From:To:Subject:Date:In-Reply-To:References:List-ID:From; b=bqYNCy+U7SBBRwq8CbB1vBfBzfy8b9faztebJHLkHFWy390nWuU4KmMPNkAfnEP/z uQ/Q11WsQArMHOfC8jfS6TOAqV1ilYYyt8t5HdXWIiR6fgBGB2W5gFgznqKWBfYXcs ffcAEDagMNm9ptXnSgJVAM6OAP7Lm//Kp7U9pqcg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732244AbgDAS7G (ORCPT ); Wed, 1 Apr 2020 14:59:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:36666 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731541AbgDAS7F (ORCPT ); Wed, 1 Apr 2020 14:59:05 -0400 Received: from localhost.localdomain (c-68-36-133-222.hsd1.mi.comcast.net [68.36.133.222]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 86A6320787 for ; Wed, 1 Apr 2020 18:59:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585767544; bh=MKetfRiAoJ6gMAtmHOaUq82VqNYGDdavL/eLNN/n6FM=; h=From:To:Subject:Date:In-Reply-To:References:From; b=wunil7Ij9n1joMP5laoZharE66h7QMtaX64fIQ4+W1PJ3USDwBblXhPl6yh/wYKyv 7zPc8m0bLLsXlADzwUhRy7k6ifydexXuHRN0Jq7WJLF+K2WWyKf8y/3LiClMmDGM4C OLmqnLJFJ50hEOVOsH4LzadZLUcAVG8WlW2/rY6k= From: trondmy@kernel.org To: linux-nfs@vger.kernel.org Subject: [PATCH 09/10] NFS: Refactor nfs_lock_and_join_requests() Date: Wed, 1 Apr 2020 14:56:51 -0400 Message-Id: <20200401185652.1904777-10-trondmy@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200401185652.1904777-9-trondmy@kernel.org> References: <20200401185652.1904777-1-trondmy@kernel.org> <20200401185652.1904777-2-trondmy@kernel.org> <20200401185652.1904777-3-trondmy@kernel.org> <20200401185652.1904777-4-trondmy@kernel.org> <20200401185652.1904777-5-trondmy@kernel.org> <20200401185652.1904777-6-trondmy@kernel.org> <20200401185652.1904777-7-trondmy@kernel.org> <20200401185652.1904777-8-trondmy@kernel.org> <20200401185652.1904777-9-trondmy@kernel.org> MIME-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org From: Trond Myklebust Refactor nfs_lock_and_join_requests() in order to separate out the subrequest merging into its own function nfs_lock_and_join_group() that can be used by O_DIRECT. Signed-off-by: Trond Myklebust --- fs/nfs/pagelist.c | 26 ++++++- fs/nfs/write.c | 164 +++++++++++++++++++++++---------------- include/linux/nfs_page.h | 1 + 3 files changed, 123 insertions(+), 68 deletions(-) diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c index b9805d1dac75..f61f96603df7 100644 --- a/fs/nfs/pagelist.c +++ b/fs/nfs/pagelist.c @@ -130,6 +130,25 @@ nfs_async_iocounter_wait(struct rpc_task *task, struct nfs_lock_context *l_ctx) } EXPORT_SYMBOL_GPL(nfs_async_iocounter_wait); +/* + * nfs_page_lock_head_request - page lock the head of the page group + * @req: any member of the page group + */ +struct nfs_page * +nfs_page_group_lock_head(struct nfs_page *req) +{ + struct nfs_page *head = req->wb_head; + + while (!nfs_lock_request(head)) { + int ret = nfs_wait_on_request(head); + if (ret < 0) + return ERR_PTR(ret); + } + if (head != req) + kref_get(&head->wb_kref); + return head; +} + /* * nfs_unroll_locks - unlock all newly locked reqs and wait on @req * @head: head request of page group, must be holding head lock @@ -186,14 +205,16 @@ nfs_page_group_lock_subreq(struct nfs_page *head, struct nfs_page *subreq) * @head: head request of page group * * This is a helper function for nfs_lock_and_join_requests which - * must be called with the head request and page group both locked. - * On error, it returns with the page group unlocked. + * must be called with the head request locked. */ int nfs_page_group_lock_subrequests(struct nfs_page *head) { struct nfs_page *subreq; int ret; + ret = nfs_page_group_lock(head); + if (ret < 0) + return ret; /* lock each request in the page group */ for (subreq = head->wb_this_page; subreq != head; subreq = subreq->wb_this_page) { @@ -201,6 +222,7 @@ int nfs_page_group_lock_subrequests(struct nfs_page *head) if (ret < 0) return ret; } + nfs_page_group_unlock(head); return 0; } diff --git a/fs/nfs/write.c b/fs/nfs/write.c index 832cf57ea442..63b64333c3ea 100644 --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -149,6 +149,31 @@ static void nfs_io_completion_put(struct nfs_io_completion *ioc) kref_put(&ioc->refcount, nfs_io_completion_release); } +static void +nfs_page_set_inode_ref(struct nfs_page *req, struct inode *inode) +{ + if (!test_and_set_bit(PG_INODE_REF, &req->wb_flags)) { + kref_get(&req->wb_kref); + atomic_long_inc(&NFS_I(inode)->nrequests); + } +} + +static int +nfs_cancel_remove_inode(struct nfs_page *req, struct inode *inode) +{ + int ret; + + if (!test_bit(PG_REMOVE, &req->wb_flags)) + return 0; + ret = nfs_page_group_lock(req); + if (ret) + return ret; + if (test_and_clear_bit(PG_REMOVE, &req->wb_flags)) + nfs_page_set_inode_ref(req, inode); + nfs_page_group_unlock(req); + return 0; +} + static struct nfs_page * nfs_page_private_request(struct page *page) { @@ -218,6 +243,36 @@ static struct nfs_page *nfs_page_find_head_request(struct page *page) return req; } +static struct nfs_page *nfs_find_and_lock_page_request(struct page *page) +{ + struct inode *inode = page_file_mapping(page)->host; + struct nfs_page *req, *head; + int ret; + + for (;;) { + req = nfs_page_find_head_request(page); + if (!req) + return req; + head = nfs_page_group_lock_head(req); + if (head != req) + nfs_release_request(req); + if (IS_ERR(head)) + return head; + ret = nfs_cancel_remove_inode(head, inode); + if (ret < 0) { + nfs_unlock_and_release_request(head); + return ERR_PTR(ret); + } + /* Ensure that nobody removed the request before we locked it */ + if (head == nfs_page_private_request(page)) + break; + if (PageSwapCache(page)) + break; + nfs_unlock_and_release_request(head); + } + return head; +} + /* Adjust the file length if we're writing beyond the end */ static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count) { @@ -436,65 +491,22 @@ nfs_destroy_unlinked_subrequests(struct nfs_page *destroy_list, } /* - * nfs_lock_and_join_requests - join all subreqs to the head req and return - * a locked reference, cancelling any pending - * operations for this page. - * - * @page - the page used to lookup the "page group" of nfs_page structures + * nfs_join_page_group - destroy subrequests of the head req + * @head: the page used to lookup the "page group" of nfs_page structures + * @inode: Inode to which the request belongs. * * This function joins all sub requests to the head request by first * locking all requests in the group, cancelling any pending operations * and finally updating the head request to cover the whole range covered by * the (former) group. All subrequests are removed from any write or commit * lists, unlinked from the group and destroyed. - * - * Returns a locked, referenced pointer to the head request - which after - * this call is guaranteed to be the only request associated with the page. - * Returns NULL if no requests are found for @page, or a ERR_PTR if an - * error was encountered. */ -static struct nfs_page * -nfs_lock_and_join_requests(struct page *page) +static void +nfs_join_page_group(struct nfs_page *head, struct inode *inode) { - struct inode *inode = page_file_mapping(page)->host; - struct nfs_page *head, *subreq; + struct nfs_page *subreq; struct nfs_page *destroy_list = NULL; unsigned int pgbase, off, bytes; - int ret; - -try_again: - /* - * A reference is taken only on the head request which acts as a - * reference to the whole page group - the group will not be destroyed - * until the head reference is released. - */ - head = nfs_page_find_head_request(page); - if (!head) - return NULL; - - /* lock the page head first in order to avoid an ABBA inefficiency */ - if (!nfs_lock_request(head)) { - ret = nfs_wait_on_request(head); - nfs_release_request(head); - if (ret < 0) - return ERR_PTR(ret); - goto try_again; - } - - /* Ensure that nobody removed the request before we locked it */ - if (head != nfs_page_private_request(page) && !PageSwapCache(page)) { - nfs_unlock_and_release_request(head); - goto try_again; - } - - ret = nfs_page_group_lock(head); - if (ret < 0) - goto release_request; - - /* lock each request in the page group */ - ret = nfs_page_group_lock_subrequests(head); - if (ret < 0) - goto release_request; pgbase = head->wb_pgbase; bytes = head->wb_bytes; @@ -531,30 +543,50 @@ nfs_lock_and_join_requests(struct page *page) head->wb_this_page = head; } - /* Postpone destruction of this request */ - if (test_and_clear_bit(PG_REMOVE, &head->wb_flags)) { - set_bit(PG_INODE_REF, &head->wb_flags); - kref_get(&head->wb_kref); - atomic_long_inc(&NFS_I(inode)->nrequests); - } + nfs_destroy_unlinked_subrequests(destroy_list, head, inode); +} - nfs_page_group_unlock(head); +/* + * nfs_lock_and_join_requests - join all subreqs to the head req + * @page: the page used to lookup the "page group" of nfs_page structures + * + * This function joins all sub requests to the head request by first + * locking all requests in the group, cancelling any pending operations + * and finally updating the head request to cover the whole range covered by + * the (former) group. All subrequests are removed from any write or commit + * lists, unlinked from the group and destroyed. + * + * Returns a locked, referenced pointer to the head request - which after + * this call is guaranteed to be the only request associated with the page. + * Returns NULL if no requests are found for @page, or a ERR_PTR if an + * error was encountered. + */ +static struct nfs_page * +nfs_lock_and_join_requests(struct page *page) +{ + struct inode *inode = page_file_mapping(page)->host; + struct nfs_page *head; + int ret; - nfs_destroy_unlinked_subrequests(destroy_list, head, inode); + /* + * A reference is taken only on the head request which acts as a + * reference to the whole page group - the group will not be destroyed + * until the head reference is released. + */ + head = nfs_find_and_lock_page_request(page); + if (IS_ERR_OR_NULL(head)) + return head; - /* Did we lose a race with nfs_inode_remove_request()? */ - if (!(PagePrivate(page) || PageSwapCache(page))) { + /* lock each request in the page group */ + ret = nfs_page_group_lock_subrequests(head); + if (ret < 0) { nfs_unlock_and_release_request(head); - return NULL; + return ERR_PTR(ret); } - /* still holds ref on head from nfs_page_find_head_request - * and still has lock on head from lock loop */ - return head; + nfs_join_page_group(head, inode); -release_request: - nfs_unlock_and_release_request(head); - return ERR_PTR(ret); + return head; } static void nfs_write_error(struct nfs_page *req, int error) diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h index dd205bc6bc58..99198c039bd6 100644 --- a/include/linux/nfs_page.h +++ b/include/linux/nfs_page.h @@ -139,6 +139,7 @@ extern size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc, extern int nfs_wait_on_request(struct nfs_page *); extern void nfs_unlock_request(struct nfs_page *req); extern void nfs_unlock_and_release_request(struct nfs_page *); +extern struct nfs_page *nfs_page_group_lock_head(struct nfs_page *req); extern int nfs_page_group_lock_subrequests(struct nfs_page *head); extern int nfs_page_group_lock(struct nfs_page *); extern void nfs_page_group_unlock(struct nfs_page *);