From: Tejun Heo Subject: [PATCH 7/8] writeback: add lockdep annotation to inode_to_wb() Date: Mon, 23 Mar 2015 01:25:43 -0400 Message-ID: <1427088344-17542-8-git-send-email-tj@kernel.org> References: <1427088344-17542-1-git-send-email-tj@kernel.org> Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references; bh=oAA0vczux2BkSbmkopgYUpuZlLP5H4dmLZElsAg2HMA=; b=jM6GJXK++xOfJP+gWYv6eCn2B7VZizi8QsKIa2qegmRuIOOR/qJghtwZCMOLh/pjEE MWmHwAdFfqtfBSI25JfFdy/gULk2x04tYoIkij9wzGlG2wV7LAEbc4L11ccAYRRmOgJp uHyQMBxqUJcDoPjOacgMoLTRbi4Wn52T778hn9ul9Iop6Jx6zVK3B0NeIjxt2qjrvGvX T51q9jJ+DbBcjvG1u/A9oIj83/7UhWrgQxBn0CyraYUwCwePYHB2B8Ird21Y1I+iUCmM 5jbGu0aoU7UcWIY2MNRRgtKn0D6WGe7IhHZCrBfIN6uF3uJf6M1hKG29bjs5765WeQ68 HQOg== In-Reply-To: <1427088344-17542-1-git-send-email-tj@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: axboe@kernel.dk Cc: linux-kernel@vger.kernel.org, jack@suse.cz, hch@infradead.org, hannes@cmpxchg.org, linux-fsdevel@vger.kernel.org, vgoyal@redhat.com, lizefan@huawei.com, cgroups@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.cz, clm@fb.com, fengguang.wu@intel.com, david@fromorbit.com, gthelen@google.com, Tejun Heo With the previous two patches, all operations which acquire wb from inode are either under one of inode->i_lock, mapping->tree_lock or wb->list_lock, or protected by stat transaction, which will be depended upon by foreign inode wb switching. This patch adds lockdep assertion to inode_to_wb() so that usages outside the above list locks can be caught easily. inode_wb_stat_unlocked_begin() is an exception as it's usually protected by combination of !I_WB_SWITCH and rcu_read_lock(). It's updated to dereference inode->i_wb directly. Signed-off-by: Tejun Heo Cc: Jens Axboe Cc: Jan Kara Cc: Wu Fengguang Cc: Greg Thelen --- include/linux/backing-dev.h | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 040be1a..b9937e5 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -326,10 +326,18 @@ wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp) * inode_to_wb - determine the wb of an inode * @inode: inode of interest * - * Returns the wb @inode is currently associated with. + * Returns the wb @inode is currently associated with. The caller must be + * holding either @inode->i_lock, @inode->i_mapping->tree_lock, or the + * associated wb's list_lock. */ static inline struct bdi_writeback *inode_to_wb(struct inode *inode) { +#ifdef CONFIG_LOCKDEP + WARN_ON_ONCE(debug_locks && + (!lockdep_is_held(&inode->i_lock) && + !lockdep_is_held(&inode->i_mapping->tree_lock) && + !lockdep_is_held(&inode->i_wb->list_lock))); +#endif return inode->i_wb; } @@ -360,7 +368,12 @@ inode_wb_stat_unlocked_begin(struct inode *inode, bool *lockedp) if (unlikely(*lockedp)) spin_lock_irq(&inode->i_mapping->tree_lock); - return inode_to_wb(inode); + + /* + * Protected by either !I_WB_SWITCH + rcu_read_lock() or tree_lock. + * inode_to_wb() will bark. Deref directly. + */ + return inode->i_wb; } /** -- 2.1.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org