From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: [PATCH v6 23/99] page cache: Add page_cache_range_empty function Date: Wed, 17 Jan 2018 12:20:47 -0800 Message-ID: <20180117202203.19756-24-willy@infradead.org> References: <20180117202203.19756-1-willy@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; h=References:In-Reply-To:Message-Id:Date:Subject:Cc: To:From:Sender:Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=WmXvZpBeEv3qtPchMWQI6SbRbU4BFsdbZY1NmyUCjzA=; b=Me4VLcMCkCsGh5xBWvCkhEsPMi INPMcqr1VMQGDU/Ainvr8Hls4Q4bMS11LI1+8BkXWlTYIf8B7MWyujPz3kpMH6mHX2Q9oQDZRB2/P iZA+Do7SuyYzUt+nx2UjjQc3fFqk18bqtvhj3Cd4WcRsseJUmesGMdDa9XmUy7UjzjJk=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x ; h=References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To :MIME-Version:Content-Type:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=WmXvZpBeEv3qtPchMWQI6SbRbU4BFsdbZY1NmyUCjzA=; b=X7lFFa3leh0ycldr+Fme0ZDHqp l9/JQJf1lXmYFzlQO6e2zGH2r8l9X1vwVIYXsPsGN0E6yapLe/nz3mk8RFZXOKBsOwywiMk2hsELc iQUq0zAZpedXxKm/SVkuYKBNogxQ81JYLuWmRYa0GHce1TStBFeOKal6faPJinyXGndY=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=References:In-Reply-To:Message-Id: Date:Subject:Cc:To:From:Sender:Reply-To:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=WmXvZpBeEv3qtPchMWQI6SbRbU4BFsdbZY1NmyUCjzA=; b=fBRusbgXml36No4xMHUBJwOhM j5GTTwVT6Ob5cGko5KxsFYyPM13/e9cBfgi/nCFevIeIrsh38jORN24XOTdC/E9jbk/Zo3jz8XEJu rkRzT/RGt57RF6S8J7COrTOwJxPpgCkhi6jsaIaqcen30Jbcv88B7VcvY6J71wykpW6+f/Nb0lE88 X4bzOUKWtc8ops93tkaI6MplaqZzdV7zy+dKE6BqMV0bnT+OeAlHSioj7JjfH2nHzVhPVui21q5Hd ee97upY9aj3iuGzeJrOvN1VKF1JGJWsyJgelDW4eVtSe08Yv/CfHBJzrJh1Fd8jo3Vzxk5MFdpl16 Y6AoGezrA==; In-Reply-To: <20180117202203.19756-1-willy@infradead.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net To: linux-kernel@vger.kernel.org Cc: linux-s390@vger.kernel.org, David Howells , linux-nilfs@vger.kernel.org, Matthew Wilcox , linux-sh@vger.kernel.org, intel-gfx@lists.freedesktop.org, linux-usb@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Stefano Stabellini , linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org, Bjorn Andersson , linux-btrfs@vger.kernel.org From: Matthew Wilcox btrfs has its own custom function for determining whether the page cache has any pages in a particular range. Move this functionality to the page cache, and call it from btrfs. Signed-off-by: Matthew Wilcox --- fs/btrfs/btrfs_inode.h | 7 ++++- fs/btrfs/inode.c | 70 ------------------------------------------------- include/linux/pagemap.h | 2 ++ mm/filemap.c | 26 ++++++++++++++++++ 4 files changed, 34 insertions(+), 71 deletions(-) diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h index 63f0ccc92a71..a48bd6e0a0bb 100644 --- a/fs/btrfs/btrfs_inode.h +++ b/fs/btrfs/btrfs_inode.h @@ -365,6 +365,11 @@ static inline void btrfs_print_data_csum_error(struct btrfs_inode *inode, logical_start, csum, csum_expected, mirror_num); } -bool btrfs_page_exists_in_range(struct inode *inode, loff_t start, loff_t end); +static inline bool btrfs_page_exists_in_range(struct inode *inode, + loff_t start, loff_t end) +{ + return page_cache_range_empty(inode->i_mapping, start >> PAGE_SHIFT, + end >> PAGE_SHIFT); +} #endif diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index dbdb5bf6bca1..d7d2c556d5a2 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -7541,76 +7541,6 @@ noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len, return ret; } -bool btrfs_page_exists_in_range(struct inode *inode, loff_t start, loff_t end) -{ - struct radix_tree_root *root = &inode->i_mapping->pages; - bool found = false; - void **pagep = NULL; - struct page *page = NULL; - unsigned long start_idx; - unsigned long end_idx; - - start_idx = start >> PAGE_SHIFT; - - /* - * end is the last byte in the last page. end == start is legal - */ - end_idx = end >> PAGE_SHIFT; - - rcu_read_lock(); - - /* Most of the code in this while loop is lifted from - * find_get_page. It's been modified to begin searching from a - * page and return just the first page found in that range. If the - * found idx is less than or equal to the end idx then we know that - * a page exists. If no pages are found or if those pages are - * outside of the range then we're fine (yay!) */ - while (page == NULL && - radix_tree_gang_lookup_slot(root, &pagep, NULL, start_idx, 1)) { - page = radix_tree_deref_slot(pagep); - if (unlikely(!page)) - break; - - if (radix_tree_exception(page)) { - if (radix_tree_deref_retry(page)) { - page = NULL; - continue; - } - /* - * Otherwise, shmem/tmpfs must be storing a swap entry - * here so return it without attempting to raise page - * count. - */ - page = NULL; - break; /* TODO: Is this relevant for this use case? */ - } - - if (!page_cache_get_speculative(page)) { - page = NULL; - continue; - } - - /* - * Has the page moved? - * This is part of the lockless pagecache protocol. See - * include/linux/pagemap.h for details. - */ - if (unlikely(page != *pagep)) { - put_page(page); - page = NULL; - } - } - - if (page) { - if (page->index <= end_idx) - found = true; - put_page(page); - } - - rcu_read_unlock(); - return found; -} - static int lock_extent_direct(struct inode *inode, u64 lockstart, u64 lockend, struct extent_state **cached_state, int writing) { diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 0db127c3ccac..34d4fa3ad1c5 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -245,6 +245,8 @@ pgoff_t page_cache_next_gap(struct address_space *mapping, pgoff_t index, unsigned long max_scan); pgoff_t page_cache_prev_gap(struct address_space *mapping, pgoff_t index, unsigned long max_scan); +bool page_cache_range_empty(struct address_space *mapping, + pgoff_t index, pgoff_t max); #define FGP_ACCESSED 0x00000001 #define FGP_LOCK 0x00000002 diff --git a/mm/filemap.c b/mm/filemap.c index 146e8ec16ec0..f1b4480723dd 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1398,6 +1398,32 @@ pgoff_t page_cache_prev_gap(struct address_space *mapping, } EXPORT_SYMBOL(page_cache_prev_gap); +bool page_cache_range_empty(struct address_space *mapping, pgoff_t index, + pgoff_t max) +{ + struct page *page; + XA_STATE(xas, &mapping->pages, index); + + rcu_read_lock(); + do { + page = xas_find(&xas, max); + if (xas_retry(&xas, page)) + continue; + /* Shadow entries don't count */ + if (xa_is_value(page)) + continue; + /* + * We don't need to try to pin this page; we're about to + * release the RCU lock anyway. It is enough to know that + * there was a page here recently. + */ + } while (0); + rcu_read_unlock(); + + return page != NULL; +} +EXPORT_SYMBOL_GPL(page_cache_range_empty); + /** * find_get_entry - find and get a page cache entry * @mapping: the address_space to search -- 2.15.1 ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot