From patchwork Fri Jun 3 05:37:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shiyang Ruan X-Patchwork-Id: 12868546 Received: from heian.cn.fujitsu.com (mail.cn.fujitsu.com [183.91.158.132]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 8F51AA4C for ; Fri, 3 Jun 2022 05:37:52 +0000 (UTC) IronPort-Data: A9a23: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 IronPort-HdrOrdr: A9a23:y8JKfK0V4IPPuv1tQ8WQjAqjBI4kLtp133Aq2lEZdPU1SL39qynKppkmPHDP5gr5J0tLpTntAsi9qBDnhPtICOsqTNSftWDd0QPGEGgI1/qB/9SPIU3D398Y/aJhXow7M9foEGV95PyQ3CCIV/om3/mLmZrFudvj X-IronPort-AV: E=Sophos;i="5.88,333,1635177600"; d="scan'208";a="124686800" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 03 Jun 2022 13:37:44 +0800 Received: from G08CNEXMBPEKD06.g08.fujitsu.local (unknown [10.167.33.206]) by cn.fujitsu.com (Postfix) with ESMTP id 60BAF4D1719C; Fri, 3 Jun 2022 13:37:44 +0800 (CST) Received: from G08CNEXCHPEKD07.g08.fujitsu.local (10.167.33.80) by G08CNEXMBPEKD06.g08.fujitsu.local (10.167.33.206) with Microsoft SMTP Server (TLS) id 15.0.1497.23; Fri, 3 Jun 2022 13:37:43 +0800 Received: from irides.mr.mr (10.167.225.141) by G08CNEXCHPEKD07.g08.fujitsu.local (10.167.33.209) with Microsoft SMTP Server id 15.0.1497.23 via Frontend Transport; Fri, 3 Jun 2022 13:37:44 +0800 From: Shiyang Ruan To: , , , , CC: , , , , , , , , , , , Christoph Hellwig Subject: [PATCH v2 04/14] fsdax: Introduce dax_lock_mapping_entry() Date: Fri, 3 Jun 2022 13:37:28 +0800 Message-ID: <20220603053738.1218681-5-ruansy.fnst@fujitsu.com> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220603053738.1218681-1-ruansy.fnst@fujitsu.com> References: <20220603053738.1218681-1-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: 60BAF4D1719C.A0A77 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 Reviewed-by: Darrick J. Wong --- 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 4155a6107fa1..65e44d78b3bb 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 cf85fc36da5f..7116681b48c0 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -161,6 +161,10 @@ 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) { @@ -188,6 +192,17 @@ 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,