From patchwork Sun Apr 10 16:09:01 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shiyang Ruan X-Patchwork-Id: 12808181 Received: from heian.cn.fujitsu.com (mail.cn.fujitsu.com [183.91.158.132]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 4B0201375 for ; Sun, 10 Apr 2022 16:09:36 +0000 (UTC) IronPort-Data: A9a23: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 IronPort-HdrOrdr: A9a23:lD4Ai680vM+pUCyHVNtuk+A+I+orL9Y04lQ7vn2YSXRuE/Bw8Pre5cjztCWE8Ar5N0tQ+uxoVJPufZqYz+8Q3WBzB8bFYOCFghrLEGgK1+KLqFeMdxEWtNQtspuIGJIfNDSfNzZHZL7BkWyF+sgbsaW62ZHtleHD1G1sUA0vT6lh6j1yAgGdHlYefng9ObMJUIqb+tFcpyetPVAebsGADHEDWOTZ4/LRkpaOW296OzcXrBmJkSiz6KP3VzyR3hIlWTtJxrs4tUjp+jaJnZmejw== X-IronPort-AV: E=Sophos;i="5.88,333,1635177600"; d="scan'208";a="123453823" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 11 Apr 2022 00:09:14 +0800 Received: from G08CNEXMBPEKD06.g08.fujitsu.local (unknown [10.167.33.206]) by cn.fujitsu.com (Postfix) with ESMTP id C00324D17163; Mon, 11 Apr 2022 00:09:08 +0800 (CST) Received: from G08CNEXJMPEKD02.g08.fujitsu.local (10.167.33.202) by G08CNEXMBPEKD06.g08.fujitsu.local (10.167.33.206) with Microsoft SMTP Server (TLS) id 15.0.1497.23; Mon, 11 Apr 2022 00:09:08 +0800 Received: from G08CNEXCHPEKD09.g08.fujitsu.local (10.167.33.85) by G08CNEXJMPEKD02.g08.fujitsu.local (10.167.33.202) with Microsoft SMTP Server (TLS) id 15.0.1497.23; Mon, 11 Apr 2022 00:09:11 +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; Mon, 11 Apr 2022 00:09:07 +0800 From: Shiyang Ruan To: , , , , CC: , , , , , Christoph Hellwig Subject: [PATCH v12 4/7] fsdax: Introduce dax_lock_mapping_entry() Date: Mon, 11 Apr 2022 00:09:01 +0800 Message-ID: <20220410160904.3758789-5-ruansy.fnst@fujitsu.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220410160904.3758789-1-ruansy.fnst@fujitsu.com> References: <20220410160904.3758789-1-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: C00324D17163.AF597 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 1ac12e877f4f..57efd3f73655 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 9c426a207ba8..c152f315d1c9 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -143,6 +143,10 @@ 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) { @@ -170,6 +174,17 @@ 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,