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Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1fUN0Z-0001fg-Fm; Sun, 17 Jun 2018 02:01:35 +0000 From: Matthew Wilcox To: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Matthew Wilcox , Jan Kara , Jeff Layton , Lukas Czerner , Ross Zwisler , Christoph Hellwig , Goldwyn Rodrigues , Nicholas Piggin , Ryusuke Konishi , linux-nilfs@vger.kernel.org, Jaegeuk Kim , Chao Yu , linux-f2fs-devel@lists.sourceforge.net Subject: [PATCH v14 68/74] dax: Convert dax_lock_page to XArray Date: Sat, 16 Jun 2018 19:00:46 -0700 Message-Id: <20180617020052.4759-69-willy@infradead.org> X-Mailer: git-send-email 2.14.3 In-Reply-To: <20180617020052.4759-1-willy@infradead.org> References: <20180617020052.4759-1-willy@infradead.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Signed-off-by: Matthew Wilcox --- fs/dax.c | 96 +++++++++++++++++++++++++++++--------------------------- 1 file changed, 50 insertions(+), 46 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index 08595ffde566..54a01380527a 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -99,6 +99,22 @@ static void *dax_make_locked(unsigned long pfn, unsigned long flags) DAX_LOCKED); } +static unsigned long dax_is_pmd_entry(void *entry) +{ + return xa_to_value(entry) & DAX_PMD; +} + +static void *dax_make_entry(pfn_t pfn, unsigned long flags) +{ + return xa_mk_value(flags | (pfn_t_to_pfn(pfn) << DAX_SHIFT)); +} + +static void *dax_make_page_entry(struct page *page, void *entry) +{ + pfn_t pfn = page_to_pfn_t(page); + return dax_make_entry(pfn, dax_is_pmd_entry(entry)); +} + static bool dax_is_locked(void *entry) { return xa_to_value(entry) & DAX_LOCKED; @@ -111,11 +127,6 @@ static unsigned int dax_entry_order(void *entry) return 0; } -static int dax_is_pmd_entry(void *entry) -{ - return xa_to_value(entry) & DAX_PMD; -} - static int dax_is_pte_entry(void *entry) { return !(xa_to_value(entry) & DAX_PMD); @@ -466,78 +477,71 @@ static struct page *dax_busy_page(void *entry) struct page *dax_lock_page(unsigned long pfn) { - pgoff_t index; - struct inode *inode; - wait_queue_head_t *wq; - void *entry = NULL, **slot; + struct page *page = pfn_to_page(pfn); + XA_STATE(xas, NULL, 0); + void *entry; struct address_space *mapping; - struct wait_exceptional_entry_queue ewait; - struct page *ret = NULL, *page = pfn_to_page(pfn); - rcu_read_lock(); for (;;) { + rcu_read_lock(); mapping = READ_ONCE(page->mapping); - if (!mapping || !IS_DAX(mapping->host)) + if (!mapping || !IS_DAX(mapping->host)) { + page = NULL; break; + } /* * In the device-dax case there's no need to lock, a * struct dev_pagemap pin is sufficient to keep the * inode alive. */ - inode = mapping->host; - if (S_ISCHR(inode->i_mode)) { - ret = page; + if (S_ISCHR(mapping->host->i_mode)) break; - } - xa_lock_irq(&mapping->i_pages); + xas.xa = &mapping->i_pages; + xas_lock_irq(&xas); + rcu_read_unlock(); if (mapping != page->mapping) { xa_unlock_irq(&mapping->i_pages); continue; } - index = page->index; - - init_wait(&ewait.wait); - ewait.wait.func = wake_exceptional_entry_func; - - entry = __radix_tree_lookup(&mapping->i_pages, index, NULL, - &slot); - if (!entry || WARN_ON_ONCE(!xa_is_value(entry))) { - xa_unlock_irq(&mapping->i_pages); - break; - } else if (!slot_locked(mapping, slot)) { - lock_slot(mapping, slot); - ret = page; - xa_unlock_irq(&mapping->i_pages); - break; + xas_set(&xas, page->index); + entry = xas_load(&xas); + if (dax_is_locked(entry)) { + entry = get_unlocked_entry(&xas); + /* Did the page move while we slept? */ + if (dax_to_pfn(entry) != pfn) { + xas_unlock_irq(&xas); + continue; + } } - - wq = dax_entry_waitqueue(&mapping->i_pages, index, entry, - &ewait.key); - prepare_to_wait_exclusive(wq, &ewait.wait, - TASK_UNINTERRUPTIBLE); - xa_unlock_irq(&mapping->i_pages); - rcu_read_unlock(); - schedule(); - finish_wait(wq, &ewait.wait); - rcu_read_lock(); + dax_lock_entry(&xas, entry); + xas_unlock_irq(&xas); + goto out; } rcu_read_unlock(); +out: return page; } void dax_unlock_page(struct page *page) { struct address_space *mapping = page->mapping; - struct inode *inode = mapping->host; + XA_STATE(xas, &mapping->i_pages, page->index); + void *entry; - if (S_ISCHR(inode->i_mode)) + if (S_ISCHR(mapping->host->i_mode)) return; - dax_unlock_mapping_entry(mapping, page->index); + xas_lock_irq(&xas); + entry = xas_load(&xas); + BUG_ON(!dax_is_locked(entry)); + entry = dax_make_page_entry(page, entry); + xas_store(&xas, entry); + dax_wake_entry(&xas, entry, false); + xas_unlock_irq(&xas); } /* -- 2.17.1