From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qa0-f52.google.com (mail-qa0-f52.google.com [209.85.216.52]) by kanga.kvack.org (Postfix) with ESMTP id B16C46B0175 for ; Tue, 6 Jan 2015 16:27:44 -0500 (EST) Received: by mail-qa0-f52.google.com with SMTP id v10so189138qac.11 for ; Tue, 06 Jan 2015 13:27:44 -0800 (PST) Received: from mail-qc0-x231.google.com (mail-qc0-x231.google.com. [2607:f8b0:400d:c01::231]) by mx.google.com with ESMTPS id q1si65666393qcc.24.2015.01.06.13.27.43 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 06 Jan 2015 13:27:43 -0800 (PST) Received: by mail-qc0-f177.google.com with SMTP id x3so60372qcv.36 for ; Tue, 06 Jan 2015 13:27:43 -0800 (PST) From: Tejun Heo Subject: [PATCH 41/45] writeback: make __writeback_single_inode() cgroup writeback aware Date: Tue, 6 Jan 2015 16:26:18 -0500 Message-Id: <1420579582-8516-42-git-send-email-tj@kernel.org> In-Reply-To: <1420579582-8516-1-git-send-email-tj@kernel.org> References: <1420579582-8516-1-git-send-email-tj@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: 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, Tejun Heo Metadata is always dirtied against the root cgroup and should thus be written out only by the root cgroup writeback. This patch updates __writeback_single_inode() so that it skips writing out metadata if the writeback is for a non-root cgroup. wbc_skip_metadata() is added to decide whether to skip metadata writeback. Signed-off-by: Tejun Heo Cc: Jens Axboe Cc: Jan Kara --- fs/fs-writeback.c | 29 ++++++++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index dbfd0b0..2bb14d5 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -684,6 +684,19 @@ static inline bool iwbl_still_has_dirty_pages(struct inode_wb_link *iwbl, return test_bit(IWBL_DIRTY_PAGES, &iwbl->data); } +/** + * wbc_skip_metadata - determine whether to skip writing out metadata + * @wbc: writeback_control in effect + * + * Called by __writeback_single_inode() to decide whether to skip writing + * out metadata. Metadata is always dirtied against the root cgroup and + * should only be written out by the root. + */ +static inline bool wbc_skip_metadata(struct writeback_control *wbc) +{ + return wbc->iwbl && !iwbl_is_root(wbc->iwbl); +} + #else /* CONFIG_CGROUP_WRITEBACK */ static void init_cgwb_dirty_page_context(struct dirty_context *dctx) @@ -791,6 +804,11 @@ static inline bool iwbl_still_has_dirty_pages(struct inode_wb_link *iwbl, return mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY); } +static inline bool wbc_skip_metadata(struct writeback_control *wbc) +{ + return false; +} + #endif /* CONFIG_CGROUP_WRITEBACK */ /** @@ -1128,6 +1146,7 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) struct address_space *mapping = inode->i_mapping; struct inode_wb_link *iwbl = inode_writeback_iwbl(inode, wbc); long nr_to_write = wbc->nr_to_write; + bool skip_metadata = wbc_skip_metadata(wbc); unsigned dirty; int ret; @@ -1144,7 +1163,7 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) * separate, external IO completion path and ->sync_fs for guaranteeing * inode metadata is written back correctly. */ - if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync) { + if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync && !skip_metadata) { int err = filemap_fdatawait(mapping); if (ret == 0) ret = err; @@ -1157,8 +1176,12 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) */ spin_lock(&inode->i_lock); - dirty = inode->i_state & I_DIRTY; - inode->i_state &= ~I_DIRTY; + if (skip_metadata) + dirty = inode->i_state & I_DIRTY_PAGES; + else + dirty = inode->i_state & I_DIRTY; + + inode->i_state &= ~dirty; /* * Paired with smp_mb() in __mark_inode_dirty_dctx(). This allows -- 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