From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-362987-1516223097-2-14678872885155715106 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.25, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='org', MailFrom='org' X-Spam-charsets: X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: linux-usb-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1516223096; b=ixgXTsgxF8RihYE6lLcdFD1vH9sd/drJzkpEEMtCYWqDPnf lVkPTrF95mL+gg/oTfhQxfvDvtyBn6DbDgRvR4+KMxYaVAsGq2IEidDB/q2xfuXC EBCRNuPgJoM5PmN2TsJ/aVSIFAN0pPKgCU9PSuTxbbdbyDQZpEYOsv760WCzKGcS YCbc7i6jeVL7qcvvR32pgi3Cenjn9bJM0QGf3761nOV8V9Fpy1Ow1fYkTRP05STJ Bls5KlcIpmuM3ZaeTfy0L/uqhRo4k0GJ9zpdQQu8PuptakMYeKzUPqB4dmGllOnd Mcf21NOy6uWx0ECZIuXGFmkEUGcNTjAK8AwA4Rg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:sender:list-id; s=arctest; t=1516223096; bh=E91DyQGlWlZap5VGptGVttArcBTcExpVA6/7pp2z9xI=; b=jreeAMux1Xjj ahg/lI274hDdo5xm929rZpafg9Y4nDQahsfswQXPUdDoEaPs0e306dK6KfpykaMt gq+ei89Kssc8CFv7giFVQ4Wnd4fWZJV+il4rPh+M2SUpGCcC1eumAhTkqasr+S24 kLygOCP6+ortmnGR7ijTYV4AN5uQ49c1kfQEfdPU73VFvbc5h0eavZdFABkAqo0n x6Z6YPaaAMb/6srEwy4nsUHEmr4hWHgear42JEbmK68PGin0yjglC8pzSIXWTC2t qyMblL9w/UIBrSgvr/iDgs9cVZd+thRUaHEskih0w6vr1uEubAM/+ZKeouM2ig2C vZXDME6SgA== ARC-Authentication-Results: i=1; mx6.messagingengine.com; arc=none (no signatures found); dkim=fail (message has been altered; 2048-bit rsa key sha256) header.d=infradead.org header.i=@infradead.org header.b=bDNIgNaY x-bits=2048 x-keytype=rsa x-algorithm=sha256 x-selector=bombadil.20170209; dmarc=none (p=none,has-list-id=yes,d=none) header.from=infradead.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-usb-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=infradead.org header.result=pass header_is_org_domain=yes Authentication-Results: mx6.messagingengine.com; arc=none (no signatures found); dkim=fail (message has been altered; 2048-bit rsa key sha256) header.d=infradead.org header.i=@infradead.org header.b=bDNIgNaY x-bits=2048 x-keytype=rsa x-algorithm=sha256 x-selector=bombadil.20170209; dmarc=none (p=none,has-list-id=yes,d=none) header.from=infradead.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-usb-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=infradead.org header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753533AbeAQVEv (ORCPT ); Wed, 17 Jan 2018 16:04:51 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:33101 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753531AbeAQUWe (ORCPT ); Wed, 17 Jan 2018 15:22:34 -0500 From: Matthew Wilcox To: linux-kernel@vger.kernel.org Cc: Matthew Wilcox , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-nilfs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-xfs@vger.kernel.org, linux-usb@vger.kernel.org, Bjorn Andersson , Stefano Stabellini , iommu@lists.linux-foundation.org, linux-remoteproc@vger.kernel.org, linux-s390@vger.kernel.org, intel-gfx@lists.freedesktop.org, cgroups@vger.kernel.org, linux-sh@vger.kernel.org, David Howells Subject: [PATCH v6 22/99] page cache: Convert hole search to XArray Date: Wed, 17 Jan 2018 12:20:46 -0800 Message-Id: <20180117202203.19756-23-willy@infradead.org> X-Mailer: git-send-email 2.14.3 In-Reply-To: <20180117202203.19756-1-willy@infradead.org> References: <20180117202203.19756-1-willy@infradead.org> Sender: linux-usb-owner@vger.kernel.org X-Mailing-List: linux-usb@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: Matthew Wilcox The page cache offers the ability to search for a miss in the previous or next N locations. Rather than teach the XArray about the page cache's definition of a miss, use xas_prev() and xas_next() to search the page array. This should be more efficient as it does not have to start the lookup from the top for each index. Signed-off-by: Matthew Wilcox --- fs/nfs/blocklayout/blocklayout.c | 2 +- include/linux/pagemap.h | 4 +- mm/filemap.c | 110 ++++++++++++++++++--------------------- mm/readahead.c | 4 +- 4 files changed, 55 insertions(+), 65 deletions(-) diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c index 995d707537da..7bd643538cff 100644 --- a/fs/nfs/blocklayout/blocklayout.c +++ b/fs/nfs/blocklayout/blocklayout.c @@ -826,7 +826,7 @@ static u64 pnfs_num_cont_bytes(struct inode *inode, pgoff_t idx) end = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); if (end != inode->i_mapping->nrpages) { rcu_read_lock(); - end = page_cache_next_hole(mapping, idx + 1, ULONG_MAX); + end = page_cache_next_gap(mapping, idx + 1, ULONG_MAX); rcu_read_unlock(); } diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 80a6149152d4..0db127c3ccac 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -241,9 +241,9 @@ static inline gfp_t readahead_gfp_mask(struct address_space *x) typedef int filler_t(void *, struct page *); -pgoff_t page_cache_next_hole(struct address_space *mapping, +pgoff_t page_cache_next_gap(struct address_space *mapping, pgoff_t index, unsigned long max_scan); -pgoff_t page_cache_prev_hole(struct address_space *mapping, +pgoff_t page_cache_prev_gap(struct address_space *mapping, pgoff_t index, unsigned long max_scan); #define FGP_ACCESSED 0x00000001 diff --git a/mm/filemap.c b/mm/filemap.c index 309be963140c..146e8ec16ec0 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1327,86 +1327,76 @@ int __lock_page_or_retry(struct page *page, struct mm_struct *mm, } /** - * page_cache_next_hole - find the next hole (not-present entry) - * @mapping: mapping - * @index: index - * @max_scan: maximum range to search - * - * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the - * lowest indexed hole. - * - * Returns: the index of the hole if found, otherwise returns an index - * outside of the set specified (in which case 'return - index >= - * max_scan' will be true). In rare cases of index wrap-around, 0 will - * be returned. - * - * page_cache_next_hole may be called under rcu_read_lock. However, - * like radix_tree_gang_lookup, this will not atomically search a - * snapshot of the tree at a single point in time. For example, if a - * hole is created at index 5, then subsequently a hole is created at - * index 10, page_cache_next_hole covering both indexes may return 10 - * if called under rcu_read_lock. + * page_cache_next_gap() - Find the next gap in the page cache. + * @mapping: Mapping. + * @index: Index. + * @max_scan: Maximum range to search. + * + * Search the range [index, min(index + max_scan - 1, ULONG_MAX)] for the + * gap with the lowest index. + * + * This function may be called under the rcu_read_lock. However, this will + * not atomically search a snapshot of the cache at a single point in time. + * For example, if a gap is created at index 5, then subsequently a gap is + * created at index 10, page_cache_next_gap covering both indices may + * return 10 if called under the rcu_read_lock. + * + * Return: The index of the gap if found, otherwise an index outside the + * range specified (in which case 'return - index >= max_scan' will be true). + * In the rare case of index wrap-around, 0 will be returned. */ -pgoff_t page_cache_next_hole(struct address_space *mapping, +pgoff_t page_cache_next_gap(struct address_space *mapping, pgoff_t index, unsigned long max_scan) { - unsigned long i; + XA_STATE(xas, &mapping->pages, index); - for (i = 0; i < max_scan; i++) { - struct page *page; - - page = radix_tree_lookup(&mapping->pages, index); - if (!page || xa_is_value(page)) + while (max_scan--) { + void *entry = xas_next(&xas); + if (!entry || xa_is_value(entry)) break; - index++; - if (index == 0) + if (xas.xa_index == 0) break; } - return index; + return xas.xa_index; } -EXPORT_SYMBOL(page_cache_next_hole); +EXPORT_SYMBOL(page_cache_next_gap); /** - * page_cache_prev_hole - find the prev hole (not-present entry) - * @mapping: mapping - * @index: index - * @max_scan: maximum range to search - * - * Search backwards in the range [max(index-max_scan+1, 0), index] for - * the first hole. - * - * Returns: the index of the hole if found, otherwise returns an index - * outside of the set specified (in which case 'index - return >= - * max_scan' will be true). In rare cases of wrap-around, ULONG_MAX - * will be returned. - * - * page_cache_prev_hole may be called under rcu_read_lock. However, - * like radix_tree_gang_lookup, this will not atomically search a - * snapshot of the tree at a single point in time. For example, if a - * hole is created at index 10, then subsequently a hole is created at - * index 5, page_cache_prev_hole covering both indexes may return 5 if - * called under rcu_read_lock. + * page_cache_prev_gap() - Find the next gap in the page cache. + * @mapping: Mapping. + * @index: Index. + * @max_scan: Maximum range to search. + * + * Search the range [max(index - max_scan + 1, 0), index] for the + * gap with the highest index. + * + * This function may be called under the rcu_read_lock. However, this will + * not atomically search a snapshot of the cache at a single point in time. + * For example, if a gap is created at index 10, then subsequently a gap is + * created at index 5, page_cache_prev_gap() covering both indices may + * return 5 if called under the rcu_read_lock. + * + * Return: The index of the gap if found, otherwise an index outside the + * range specified (in which case 'index - return >= max_scan' will be true). + * In the rare case of wrap-around, ULONG_MAX will be returned. */ -pgoff_t page_cache_prev_hole(struct address_space *mapping, +pgoff_t page_cache_prev_gap(struct address_space *mapping, pgoff_t index, unsigned long max_scan) { - unsigned long i; - - for (i = 0; i < max_scan; i++) { - struct page *page; + XA_STATE(xas, &mapping->pages, index); - page = radix_tree_lookup(&mapping->pages, index); - if (!page || xa_is_value(page)) + while (max_scan--) { + void *entry = xas_prev(&xas); + if (!entry || xa_is_value(entry)) break; - index--; - if (index == ULONG_MAX) + if (xas.xa_index == ULONG_MAX) break; } - return index; + return xas.xa_index; } -EXPORT_SYMBOL(page_cache_prev_hole); +EXPORT_SYMBOL(page_cache_prev_gap); /** * find_get_entry - find and get a page cache entry diff --git a/mm/readahead.c b/mm/readahead.c index 4851f002605f..f64b31b3a84a 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -329,7 +329,7 @@ static pgoff_t count_history_pages(struct address_space *mapping, pgoff_t head; rcu_read_lock(); - head = page_cache_prev_hole(mapping, offset - 1, max); + head = page_cache_prev_gap(mapping, offset - 1, max); rcu_read_unlock(); return offset - 1 - head; @@ -417,7 +417,7 @@ ondemand_readahead(struct address_space *mapping, pgoff_t start; rcu_read_lock(); - start = page_cache_next_hole(mapping, offset + 1, max_pages); + start = page_cache_next_gap(mapping, offset + 1, max_pages); rcu_read_unlock(); if (!start || start - offset > max_pages) -- 2.15.1