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b=nzNiGa63gF+2I+6JXTx9oKd657LsHdgtfzgq/S6q3oohRv3UQzNx+mHZbaGrDyyz+VtuAcOYOjT0DeDC3M0S4X2ypjuJA2fed9V3FwdVwPpVKXg6G+J1YSyy0iJOZ4JBHaYPLYVH0gtRsaqlq+aVDEI5gKpe0nmr8o+A4+fP42eeqNMSvgrrazSi1q4WKu3dshzj9/YCCIjlLvvbxVGAqQEQMTXQiWsiIyShkDAe88XiGhROkB/cEBUApAflPBKig7mAN3jhuIa7znLNsQI/xjDMWzwRKfrHWF8uc05A+RSrAIFT4kiklNg6v+R7c4eP1Tf3c1KyOSl3w8pZZQuEnw== Received: from DS0PR12MB7726.namprd12.prod.outlook.com (2603:10b6:8:130::6) by SN7PR12MB7854.namprd12.prod.outlook.com (2603:10b6:806:32b::21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7409.46; Thu, 11 Apr 2024 00:57:59 +0000 Received: from DS0PR12MB7726.namprd12.prod.outlook.com ([fe80::c5de:1187:4532:de80]) by DS0PR12MB7726.namprd12.prod.outlook.com ([fe80::c5de:1187:4532:de80%7]) with mapi id 15.20.7409.042; Thu, 11 Apr 2024 00:57:59 +0000 From: Alistair Popple To: linux-mm@kvack.org Cc: david@fromorbit.com, dan.j.williams@intel.com, jhubbard@nvidia.com, rcampbell@nvidia.com, willy@infradead.org, jgg@nvidia.com, linux-fsdevel@vger.kernel.org, jack@suse.cz, djwong@kernel.org, hch@lst.de, david@redhat.com, ruansy.fnst@fujitsu.com, nvdimm@lists.linux.dev, linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org, jglisse@redhat.com, Alistair Popple Subject: [RFC 04/10] fs/dax: Don't track page mapping/index Date: Thu, 11 Apr 2024 10:57:25 +1000 Message-ID: <322065d373bb6571b700dba4450f1759b304644a.1712796818.git-series.apopple@nvidia.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: X-ClientProxiedBy: SYBPR01CA0114.ausprd01.prod.outlook.com (2603:10c6:10:1::30) To DS0PR12MB7726.namprd12.prod.outlook.com (2603:10b6:8:130::6) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS0PR12MB7726:EE_|SN7PR12MB7854:EE_ X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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FS DAX implements it's own kind of page cache and rmap look ups so these fields are unnecessary. They are currently only used to detect error/warning conditions which should never occur. A future change will change the way shared mappings are detected by doing normal page reference counting instead, so remove the unnecessary checks. Signed-off-by: Alistair Popple --- fs/dax.c | 84 +--------------------------------------- include/linux/page-flags.h | 6 +--- 2 files changed, 90 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index 8fafecb..a7bd423 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -320,85 +320,6 @@ static unsigned long dax_end_pfn(void *entry) for (pfn = dax_to_pfn(entry); \ pfn < dax_end_pfn(entry); pfn++) -static inline bool dax_page_is_shared(struct page *page) -{ - return page->mapping == PAGE_MAPPING_DAX_SHARED; -} - -/* - * Set the page->mapping with PAGE_MAPPING_DAX_SHARED flag, increase the - * refcount. - */ -static inline void dax_page_share_get(struct page *page) -{ - if (page->mapping != PAGE_MAPPING_DAX_SHARED) { - /* - * Reset the index if the page was already mapped - * regularly before. - */ - if (page->mapping) - page->share = 1; - page->mapping = PAGE_MAPPING_DAX_SHARED; - } - page->share++; -} - -static inline unsigned long dax_page_share_put(struct page *page) -{ - return --page->share; -} - -/* - * When it is called in dax_insert_entry(), the shared flag will indicate that - * whether this entry is shared by multiple files. If so, set the page->mapping - * PAGE_MAPPING_DAX_SHARED, and use page->share as refcount. - */ -static void dax_associate_entry(void *entry, struct address_space *mapping, - struct vm_area_struct *vma, unsigned long address, bool shared) -{ - unsigned long size = dax_entry_size(entry), pfn, index; - int i = 0; - - if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) - return; - - index = linear_page_index(vma, address & ~(size - 1)); - for_each_mapped_pfn(entry, pfn) { - struct page *page = pfn_to_page(pfn); - - if (shared) { - dax_page_share_get(page); - } else { - WARN_ON_ONCE(page->mapping); - page->mapping = mapping; - page->index = index + i++; - } - } -} - -static void dax_disassociate_entry(void *entry, struct address_space *mapping, - bool trunc) -{ - unsigned long pfn; - - if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) - return; - - for_each_mapped_pfn(entry, pfn) { - struct page *page = pfn_to_page(pfn); - - WARN_ON_ONCE(trunc && page_ref_count(page) > 1); - if (dax_page_is_shared(page)) { - /* keep the shared flag if this page is still shared */ - if (dax_page_share_put(page) > 0) - continue; - } else - WARN_ON_ONCE(page->mapping && page->mapping != mapping); - page->mapping = NULL; - page->index = 0; - } -} - static struct page *dax_busy_page(void *entry) { unsigned long pfn; @@ -620,7 +541,6 @@ static void *grab_mapping_entry(struct xa_state *xas, xas_lock_irq(xas); } - dax_disassociate_entry(entry, mapping, false); xas_store(xas, NULL); /* undo the PMD join */ dax_wake_entry(xas, entry, WAKE_ALL); mapping->nrpages -= PG_PMD_NR; @@ -757,7 +677,6 @@ static int __dax_invalidate_entry(struct address_space *mapping, (xas_get_mark(&xas, PAGECACHE_TAG_DIRTY) || xas_get_mark(&xas, PAGECACHE_TAG_TOWRITE))) goto out; - dax_disassociate_entry(entry, mapping, trunc); xas_store(&xas, NULL); mapping->nrpages -= 1UL << dax_entry_order(entry); ret = 1; @@ -894,9 +813,6 @@ static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf, if (shared || dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) { void *old; - dax_disassociate_entry(entry, mapping, false); - dax_associate_entry(new_entry, mapping, vmf->vma, vmf->address, - shared); /* * Only swap our new entry into the page cache if the current * entry is a zero page or an empty entry. If a normal PTE or diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 5c02720..85d5427 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -631,12 +631,6 @@ PAGEFLAG_FALSE(VmemmapSelfHosted, vmemmap_self_hosted) #define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE) #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE) -/* - * Different with flags above, this flag is used only for fsdax mode. It - * indicates that this page->mapping is now under reflink case. - */ -#define PAGE_MAPPING_DAX_SHARED ((void *)0x1) - static __always_inline bool folio_mapping_flags(struct folio *folio) { return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) != 0;