From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: [PATCH 1/3] writeback: do foreign inode detection iff cgroup writeback is enabled Date: Tue, 16 Jun 2015 18:48:30 -0400 Message-ID: <1434494912-31043-2-git-send-email-tj@kernel.org> References: <1434494912-31043-1-git-send-email-tj@kernel.org> Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, lizefan@huawei.com, cgroups@vger.kernel.org, hannes@cmpxchg.org, kernel-team@fb.com, Tejun Heo To: axboe@kernel.dk Return-path: In-Reply-To: <1434494912-31043-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Currently, even when a filesystem doesn't set the FS_CGROUP_WRITEBACK flag, if the filesystem uses wbc_init_bio() and wbc_account_io(), the foreign inode detection and migration logic still ends up activating cgroup writeback which is unexpected. This patch ensures that the foreign inode detection logic stays disabled when inode_cgwb_enabled() is false by not associating writeback_control's with bdi_writeback's. This also avoids unnecessary operations in wbc_init_bio(), wbc_account_io() and wbc_detach_inode() for filesystems which don't support cgroup writeback. Signed-off-by: Tejun Heo --- fs/fs-writeback.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index f60de54..f0520bc 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -513,6 +513,11 @@ static void inode_switch_wbs(struct inode *inode, int new_wb_id) void wbc_attach_and_unlock_inode(struct writeback_control *wbc, struct inode *inode) { + if (!inode_cgwb_enabled(inode)) { + spin_unlock(&inode->i_lock); + return; + } + wbc->wb = inode_to_wb(inode); wbc->inode = inode; @@ -575,11 +580,16 @@ void wbc_detach_inode(struct writeback_control *wbc) { struct bdi_writeback *wb = wbc->wb; struct inode *inode = wbc->inode; - u16 history = inode->i_wb_frn_history; - unsigned long avg_time = inode->i_wb_frn_avg_time; - unsigned long max_bytes, max_time; + unsigned long avg_time, max_bytes, max_time; + u16 history; int max_id; + if (!wb) + return; + + history = inode->i_wb_frn_history; + avg_time = inode->i_wb_frn_avg_time; + /* pick the winner of this round */ if (wbc->wb_bytes >= wbc->wb_lcand_bytes && wbc->wb_bytes >= wbc->wb_tcand_bytes) { -- 2.4.3