From patchwork Sun Dec 26 14:34:35 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shiyang Ruan X-Patchwork-Id: 12699347 Received: from heian.cn.fujitsu.com (mail.cn.fujitsu.com [183.91.158.132]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A31812C9C for ; Sun, 26 Dec 2021 14:35:14 +0000 (UTC) IronPort-Data: A9a23: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 IronPort-HdrOrdr: A9a23:UhJmC6/HWeW6HHzMZgtuk+DkI+orL9Y04lQ7vn2ZKCYlFvBw8vrCoB1173HJYUkqMk3I9ergBEDiewK4yXcW2/hzAV7KZmCP11dAR7sSj7cKrQeBJwTOssZZ1YpFN5N1EcDMCzFB5vrS0U2VFMkBzbC8nJyVuQ== X-IronPort-AV: E=Sophos;i="5.88,237,1635177600"; d="scan'208";a="119563879" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 26 Dec 2021 22:35:10 +0800 Received: from G08CNEXMBPEKD04.g08.fujitsu.local (unknown [10.167.33.201]) by cn.fujitsu.com (Postfix) with ESMTP id DD6664D146F0; Sun, 26 Dec 2021 22:35:05 +0800 (CST) Received: from G08CNEXCHPEKD09.g08.fujitsu.local (10.167.33.85) by G08CNEXMBPEKD04.g08.fujitsu.local (10.167.33.201) with Microsoft SMTP Server (TLS) id 15.0.1497.23; Sun, 26 Dec 2021 22:35:07 +0800 Received: from irides.mr.mr (10.167.225.141) by G08CNEXCHPEKD09.g08.fujitsu.local (10.167.33.209) with Microsoft SMTP Server id 15.0.1497.23 via Frontend Transport; Sun, 26 Dec 2021 22:35:03 +0800 From: Shiyang Ruan To: , , , , CC: , , , , , Christoph Hellwig Subject: [PATCH v9 06/10] fsdax: Introduce dax_lock_mapping_entry() Date: Sun, 26 Dec 2021 22:34:35 +0800 Message-ID: <20211226143439.3985960-7-ruansy.fnst@fujitsu.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20211226143439.3985960-1-ruansy.fnst@fujitsu.com> References: <20211226143439.3985960-1-ruansy.fnst@fujitsu.com> Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-yoursite-MailScanner-ID: DD6664D146F0.AF738 X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: ruansy.fnst@fujitsu.com X-Spam-Status: No The current dax_lock_page() locks dax entry by obtaining mapping and index in page. To support 1-to-N RMAP in NVDIMM, we need a new function to lock a specific dax entry corresponding to this file's mapping,index. And output the page corresponding to the specific dax entry for caller use. Signed-off-by: Shiyang Ruan Reviewed-by: Christoph Hellwig --- fs/dax.c | 63 +++++++++++++++++++++++++++++++++++++++++++++ include/linux/dax.h | 15 +++++++++++ 2 files changed, 78 insertions(+) diff --git a/fs/dax.c b/fs/dax.c index 2ee2d5a525ee..b3c737aff9de 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -455,6 +455,69 @@ void dax_unlock_page(struct page *page, dax_entry_t cookie) dax_unlock_entry(&xas, (void *)cookie); } +/* + * dax_lock_mapping_entry - Lock the DAX entry corresponding to a mapping + * @mapping: the file's mapping whose entry we want to lock + * @index: the offset within this file + * @page: output the dax page corresponding to this dax entry + * + * Return: A cookie to pass to dax_unlock_mapping_entry() or 0 if the entry + * could not be locked. + */ +dax_entry_t dax_lock_mapping_entry(struct address_space *mapping, pgoff_t index, + struct page **page) +{ + XA_STATE(xas, NULL, 0); + void *entry; + + rcu_read_lock(); + for (;;) { + entry = NULL; + if (!dax_mapping(mapping)) + break; + + xas.xa = &mapping->i_pages; + xas_lock_irq(&xas); + xas_set(&xas, index); + entry = xas_load(&xas); + if (dax_is_locked(entry)) { + rcu_read_unlock(); + wait_entry_unlocked(&xas, entry); + rcu_read_lock(); + continue; + } + if (!entry || + dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) { + /* + * Because we are looking for entry from file's mapping + * and index, so the entry may not be inserted for now, + * or even a zero/empty entry. We don't think this is + * an error case. So, return a special value and do + * not output @page. + */ + entry = (void *)~0UL; + } else { + *page = pfn_to_page(dax_to_pfn(entry)); + dax_lock_entry(&xas, entry); + } + xas_unlock_irq(&xas); + break; + } + rcu_read_unlock(); + return (dax_entry_t)entry; +} + +void dax_unlock_mapping_entry(struct address_space *mapping, pgoff_t index, + dax_entry_t cookie) +{ + XA_STATE(xas, &mapping->i_pages, index); + + if (cookie == ~0UL) + return; + + dax_unlock_entry(&xas, (void *)cookie); +} + /* * Find page cache entry at given index. If it is a DAX entry, return it * with the entry locked. If the page cache doesn't contain an entry at diff --git a/include/linux/dax.h b/include/linux/dax.h index e16a9e0ee857..f602a1c462d3 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -170,6 +170,10 @@ struct page *dax_layout_busy_page(struct address_space *mapping); struct page *dax_layout_busy_page_range(struct address_space *mapping, loff_t start, loff_t end); dax_entry_t dax_lock_page(struct page *page); void dax_unlock_page(struct page *page, dax_entry_t cookie); +dax_entry_t dax_lock_mapping_entry(struct address_space *mapping, + unsigned long index, struct page **page); +void dax_unlock_mapping_entry(struct address_space *mapping, + unsigned long index, dax_entry_t cookie); #else static inline struct page *dax_layout_busy_page(struct address_space *mapping) { @@ -197,6 +201,17 @@ static inline dax_entry_t dax_lock_page(struct page *page) static inline void dax_unlock_page(struct page *page, dax_entry_t cookie) { } + +static inline dax_entry_t dax_lock_mapping_entry(struct address_space *mapping, + unsigned long index, struct page **page) +{ + return 0; +} + +static inline void dax_unlock_mapping_entry(struct address_space *mapping, + unsigned long index, dax_entry_t cookie) +{ +} #endif int dax_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,