From patchwork Mon Oct 7 15:45:25 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chandra Seetharaman X-Patchwork-Id: 2997511 Return-Path: X-Original-To: patchwork-linux-btrfs@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 3630ABF924 for ; Mon, 7 Oct 2013 15:47:16 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 7625D2017C for ; Mon, 7 Oct 2013 15:47:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5014B2010E for ; Mon, 7 Oct 2013 15:47:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755821Ab3JGPrG (ORCPT ); Mon, 7 Oct 2013 11:47:06 -0400 Received: from e37.co.us.ibm.com ([32.97.110.158]:41008 "EHLO e37.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754897Ab3JGPrD (ORCPT ); Mon, 7 Oct 2013 11:47:03 -0400 Received: from /spool/local by e37.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Mon, 7 Oct 2013 09:47:02 -0600 Received: from d03relay03.boulder.ibm.com (d03relay03.boulder.ibm.com [9.17.195.228]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id 28BE919D8051 for ; Mon, 7 Oct 2013 09:46:59 -0600 (MDT) Received: from d03av06.boulder.ibm.com (d03av06.boulder.ibm.com [9.17.195.245]) by d03relay03.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r97Fl0XF273024 for ; Mon, 7 Oct 2013 09:47:00 -0600 Received: from d03av06.boulder.ibm.com (loopback [127.0.0.1]) by d03av06.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r97Fo8Gn031501 for ; Mon, 7 Oct 2013 09:50:08 -0600 Received: from [9.41.106.170] (chandra-dt.austin.ibm.com [9.41.106.170]) by d03av06.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id r97Fo7vp031456; Mon, 7 Oct 2013 09:50:07 -0600 Subject: [PATCH] Btrfs: Simplify the logic in alloc_extent_buffer() for existing extent buffer case From: Chandra Seetharaman Reply-To: sekharan@us.ibm.com To: Btrfs mailing list Cc: Zach Brown Organization: IBM Date: Mon, 07 Oct 2013 10:45:25 -0500 Message-ID: <1381160725.22521.143.camel@chandra-dt.ibm.com> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 (2.28.3-30.el6) X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13100715-7164-0000-0000-0000023BD6FD Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Spam-Status: No, score=-7.1 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP alloc_extent_buffer() uses radix_tree_lookup() when radix_tree_insert() fails with EEXIST. That part of the code is very similar to the code in find_extent_buffer(). This patch replaces radix_tree_lookup() and surrounding code in alloc_extent_buffer() with find_extent_buffer(). Note that radix_tree_lookup() does not need to be protected by tree->buffer_lock. It is protected by eb->refs. While at it, this patch - changes the other usage of radix_tree_lookup() in alloc_extent_buffer() with find_extent_buffer() to reduce redundancy. - removes the unused argument 'len' to find_extent_buffer(). Signed-Off-by: Chandra Seetharaman Reviewed-by: Zach Brown --- -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 4ae17ed..daa04d2 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1105,8 +1105,7 @@ struct extent_buffer *btrfs_find_tree_block(struct btrfs_root *root, { struct inode *btree_inode = root->fs_info->btree_inode; struct extent_buffer *eb; - eb = find_extent_buffer(&BTRFS_I(btree_inode)->io_tree, - bytenr, blocksize); + eb = find_extent_buffer(&BTRFS_I(btree_inode)->io_tree, bytenr); return eb; } diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index c09a40d..f45b4e8 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -4451,6 +4451,23 @@ static void mark_extent_buffer_accessed(struct extent_buffer *eb) } } +struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree, + u64 start) +{ + struct extent_buffer *eb; + + rcu_read_lock(); + eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT); + if (eb && atomic_inc_not_zero(&eb->refs)) { + rcu_read_unlock(); + mark_extent_buffer_accessed(eb); + return eb; + } + rcu_read_unlock(); + + return NULL; +} + struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree, u64 start, unsigned long len) { @@ -4464,14 +4481,10 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree, int uptodate = 1; int ret; - rcu_read_lock(); - eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT); - if (eb && atomic_inc_not_zero(&eb->refs)) { - rcu_read_unlock(); - mark_extent_buffer_accessed(eb); + + eb = find_extent_buffer(tree, start); + if (eb) return eb; - } - rcu_read_unlock(); eb = __alloc_extent_buffer(tree, start, len, GFP_NOFS); if (!eb) @@ -4530,24 +4543,17 @@ again: spin_lock(&tree->buffer_lock); ret = radix_tree_insert(&tree->buffer, start >> PAGE_CACHE_SHIFT, eb); + spin_unlock(&tree->buffer_lock); + radix_tree_preload_end(); if (ret == -EEXIST) { - exists = radix_tree_lookup(&tree->buffer, - start >> PAGE_CACHE_SHIFT); - if (!atomic_inc_not_zero(&exists->refs)) { - spin_unlock(&tree->buffer_lock); - radix_tree_preload_end(); - exists = NULL; + exists = find_extent_buffer(tree, start); + if (exists) + goto free_eb; + else goto again; - } - spin_unlock(&tree->buffer_lock); - radix_tree_preload_end(); - mark_extent_buffer_accessed(exists); - goto free_eb; } /* add one reference for the tree */ check_buffer_tree_ref(eb); - spin_unlock(&tree->buffer_lock); - radix_tree_preload_end(); /* * there is a race where release page may have @@ -4578,23 +4584,6 @@ free_eb: return exists; } -struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree, - u64 start, unsigned long len) -{ - struct extent_buffer *eb; - - rcu_read_lock(); - eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT); - if (eb && atomic_inc_not_zero(&eb->refs)) { - rcu_read_unlock(); - mark_extent_buffer_accessed(eb); - return eb; - } - rcu_read_unlock(); - - return NULL; -} - static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head) { struct extent_buffer *eb = diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h index 6dbc645..a4b75af 100644 --- a/fs/btrfs/extent_io.h +++ b/fs/btrfs/extent_io.h @@ -271,7 +271,7 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree, struct extent_buffer *alloc_dummy_extent_buffer(u64 start, unsigned long len); struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src); struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree, - u64 start, unsigned long len); + u64 start); void free_extent_buffer(struct extent_buffer *eb); void free_extent_buffer_stale(struct extent_buffer *eb); #define WAIT_NONE 0