From patchwork Wed Jan 6 01:01:47 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qu Wenruo X-Patchwork-Id: 12000657 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A416CC433E9 for ; Wed, 6 Jan 2021 01:03:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6417F221E2 for ; Wed, 6 Jan 2021 01:03:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726949AbhAFBDl (ORCPT ); Tue, 5 Jan 2021 20:03:41 -0500 Received: from mx2.suse.de ([195.135.220.15]:45874 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726919AbhAFBDl (ORCPT ); Tue, 5 Jan 2021 20:03:41 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1609894941; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Pc0+aSbQMJpzM8HIr6KMbzCV2pBN7SWQEkhk6SAeqDk=; b=gY4QPBA8EAFD6s/0URRAt/loAQCR+T52aKRJioxxsqRDAEe0bE3WC+JOaN+LIEjl2Vzii0 hg46tydtvyglKMLkFVeFZZSDToZaip3/Gp9rFD2V0Br4vD9cTZQF9arDLxWxnZEZKUr6zc 2eaYau9U7+21XeUD+ugG7fJzD/oPGLo= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 53974AF3E for ; Wed, 6 Jan 2021 01:02:21 +0000 (UTC) From: Qu Wenruo To: linux-btrfs@vger.kernel.org Subject: [PATCH v3 08/22] btrfs: extent_io: make attach_extent_buffer_page() to handle subpage case Date: Wed, 6 Jan 2021 09:01:47 +0800 Message-Id: <20210106010201.37864-9-wqu@suse.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210106010201.37864-1-wqu@suse.com> References: <20210106010201.37864-1-wqu@suse.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org For subpage case, we need to allocate new memory for each metadata page. So we need to: - Allow attach_extent_buffer_page() to return int To indicate allocation failure - Prealloc page->private for alloc_extent_buffer() We don't want to call memory allocation with spinlock hold, so do preallocation before we acquire the spin lock. - Handle subpage and regular case differently in attach_extent_buffer_page() For regular case, just do the usual thing. For subpage case, allocate new memory and update the tree_block bitmap. The bitmap update will be handled by new subpage specific helper, btrfs_subpage_set_tree_block(). Signed-off-by: Qu Wenruo --- fs/btrfs/extent_io.c | 74 ++++++++++++++++++++++++++++++++++---------- fs/btrfs/subpage.h | 50 ++++++++++++++++++++++++++++++ 2 files changed, 108 insertions(+), 16 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index d60f1837f8fb..2eeff925450f 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -24,6 +24,7 @@ #include "rcu-string.h" #include "backref.h" #include "disk-io.h" +#include "subpage.h" static struct kmem_cache *extent_state_cache; static struct kmem_cache *extent_buffer_cache; @@ -3140,22 +3141,41 @@ static int submit_extent_page(unsigned int opf, return ret; } -static void attach_extent_buffer_page(struct extent_buffer *eb, +static int attach_extent_buffer_page(struct extent_buffer *eb, struct page *page) { - /* - * If the page is mapped to btree inode, we should hold the private - * lock to prevent race. - * For cloned or dummy extent buffers, their pages are not mapped and - * will not race with any other ebs. - */ - if (page->mapping) - lockdep_assert_held(&page->mapping->private_lock); + struct btrfs_fs_info *fs_info = eb->fs_info; + int ret; - if (!PagePrivate(page)) - attach_page_private(page, eb); - else - WARN_ON(page->private != (unsigned long)eb); + if (fs_info->sectorsize == PAGE_SIZE) { + /* + * If the page is mapped to btree inode, we should hold the + * private lock to prevent race. + * For cloned or dummy extent buffers, their pages are not + * mapped and will not race with any other ebs. + */ + if (page->mapping) + lockdep_assert_held(&page->mapping->private_lock); + + if (!PagePrivate(page)) + attach_page_private(page, eb); + else + WARN_ON(page->private != (unsigned long)eb); + return 0; + } + + /* Already mapped, just update the existing range */ + if (PagePrivate(page)) + goto update_bitmap; + + /* Do new allocation to attach subpage */ + ret = btrfs_attach_subpage(fs_info, page); + if (ret < 0) + return ret; + +update_bitmap: + btrfs_subpage_set_tree_block(fs_info, page, eb->start, eb->len); + return 0; } void set_page_extent_mapped(struct page *page) @@ -5063,21 +5083,29 @@ struct extent_buffer *btrfs_clone_extent_buffer(const struct extent_buffer *src) if (new == NULL) return NULL; + set_bit(EXTENT_BUFFER_UPTODATE, &new->bflags); + set_bit(EXTENT_BUFFER_UNMAPPED, &new->bflags); + for (i = 0; i < num_pages; i++) { + int ret; + p = alloc_page(GFP_NOFS); if (!p) { btrfs_release_extent_buffer(new); return NULL; } - attach_extent_buffer_page(new, p); + ret = attach_extent_buffer_page(new, p); + if (ret < 0) { + put_page(p); + btrfs_release_extent_buffer(new); + return NULL; + } WARN_ON(PageDirty(p)); SetPageUptodate(p); new->pages[i] = p; copy_page(page_address(p), page_address(src->pages[i])); } - set_bit(EXTENT_BUFFER_UPTODATE, &new->bflags); - set_bit(EXTENT_BUFFER_UNMAPPED, &new->bflags); return new; } @@ -5316,6 +5344,18 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info, goto free_eb; } + /* + * Preallocate page->private for subpage case, so that + * we won't allocate memory with private_lock hold. + */ + ret = btrfs_attach_subpage(fs_info, p); + if (ret < 0) { + unlock_page(p); + put_page(p); + exists = ERR_PTR(-ENOMEM); + goto free_eb; + } + spin_lock(&mapping->private_lock); exists = grab_extent_buffer(p); if (exists) { @@ -5325,8 +5365,10 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info, mark_extent_buffer_accessed(exists, p); goto free_eb; } + /* Should not fail, as we have attached the subpage already */ attach_extent_buffer_page(eb, p); spin_unlock(&mapping->private_lock); + WARN_ON(PageDirty(p)); eb->pages[i] = p; if (!PageUptodate(p)) diff --git a/fs/btrfs/subpage.h b/fs/btrfs/subpage.h index 96f3b226913e..e49d4a7329e1 100644 --- a/fs/btrfs/subpage.h +++ b/fs/btrfs/subpage.h @@ -23,9 +23,59 @@ struct btrfs_subpage { /* Common members for both data and metadata pages */ spinlock_t lock; + union { + /* Structures only used by metadata */ + struct { + u16 tree_block_bitmap; + }; + /* structures only used by data */ + }; }; int btrfs_attach_subpage(struct btrfs_fs_info *fs_info, struct page *page); void btrfs_detach_subpage(struct btrfs_fs_info *fs_info, struct page *page); +/* + * Convert the [start, start + len) range into a u16 bitmap + * + * E.g. if start == page_offset() + 16K, len = 16K, we get 0x00f0. + */ +static inline u16 btrfs_subpage_calc_bitmap(struct btrfs_fs_info *fs_info, + struct page *page, u64 start, u32 len) +{ + int bit_start = offset_in_page(start) >> fs_info->sectorsize_bits; + int nbits = len >> fs_info->sectorsize_bits; + + /* Basic checks */ + ASSERT(PagePrivate(page) && page->private); + ASSERT(IS_ALIGNED(start, fs_info->sectorsize) && + IS_ALIGNED(len, fs_info->sectorsize)); + + /* + * The range check only works for mapped page, we can + * still have unampped page like dummy extent buffer pages. + */ + if (page->mapping) + ASSERT(page_offset(page) <= start && + start + len <= page_offset(page) + PAGE_SIZE); + /* + * Here nbits can be 16, thus can go beyond u16 range. Here we make the + * first left shift to be calculated in unsigned long (u32), then + * truncate the result to u16. + */ + return (u16)(((1UL << nbits) - 1) << bit_start); +} + +static inline void btrfs_subpage_set_tree_block(struct btrfs_fs_info *fs_info, + struct page *page, u64 start, u32 len) +{ + struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private; + unsigned long flags; + u16 tmp = btrfs_subpage_calc_bitmap(fs_info, page, start, len); + + spin_lock_irqsave(&subpage->lock, flags); + subpage->tree_block_bitmap |= tmp; + spin_unlock_irqrestore(&subpage->lock, flags); +} + #endif /* BTRFS_SUBPAGE_H */