From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f178.google.com ([209.85.216.178]:52636 "EHLO mail-qt0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751901AbdJLRGe (ORCPT ); Thu, 12 Oct 2017 13:06:34 -0400 Date: Thu, 12 Oct 2017 10:06:28 -0700 From: Tejun Heo To: dsterba@suse.cz, jack@suse.cz, axboe@kernel.dk, clm@fb.com, jbacik@fb.com, kernel-team@fb.com, linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org Subject: [PATCH v3 5/5] btrfs: ensure that metadata and flush are issued from the root cgroup Message-ID: <20171012170628.GS3301751@devbig577.frc2.facebook.com> References: <20171010155441.753966-1-tj@kernel.org> <20171010155441.753966-6-tj@kernel.org> <20171010164325.GN3301751@devbig577.frc2.facebook.com> <20171011170723.GX3521@twin.jikos.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20171011170723.GX3521@twin.jikos.cz> Sender: linux-btrfs-owner@vger.kernel.org List-ID: Issuing metdata or otherwise shared IOs from !root cgroup can lead to priority inversion. This patch ensures that those IOs are always issued from the root cgroup. v3: Dropped unnecessary btree_inode handling as suggested by David Sterba. v2: Fixed missing @bh in submit_bh_blkcg_css() call. Signed-off-by: Tejun Heo Reviewed-by: Liu Bo Cc: David Sterba Cc: Chris Mason Cc: Josef Bacik --- fs/btrfs/check-integrity.c | 2 +- fs/btrfs/disk-io.c | 4 ++++ fs/btrfs/ioctl.c | 4 ++++ 3 files changed, 9 insertions(+), 1 deletion(-) --- a/fs/btrfs/check-integrity.c +++ b/fs/btrfs/check-integrity.c @@ -2741,7 +2741,7 @@ int btrfsic_submit_bh(int op, int op_fla struct btrfsic_dev_state *dev_state; if (!btrfsic_is_initialized) - return submit_bh(op, op_flags, bh); + return submit_bh_blkcg_css(op, op_flags, bh, blkcg_root_css); mutex_lock(&btrfsic_mutex); /* since btrfsic_submit_bh() might also be called before --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1025,6 +1025,8 @@ static blk_status_t btree_submit_bio_hoo int async = check_async_write(bio_flags); blk_status_t ret; + bio_associate_blkcg(bio, blkcg_root_css); + if (bio_op(bio) != REQ_OP_WRITE) { /* * called for a read, do the setup so that checksum validation @@ -3512,6 +3514,8 @@ static void write_dev_flush(struct btrfs return; bio_reset(bio); + bio_associate_blkcg(bio, blkcg_root_css); + bio->bi_end_io = btrfs_end_empty_barrier; bio_set_dev(bio, device->bdev); bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_PREFLUSH; --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -150,6 +150,10 @@ void btrfs_update_iflags(struct inode *i new_fl |= S_NOATIME; if (ip->flags & BTRFS_INODE_DIRSYNC) new_fl |= S_DIRSYNC; + /* + * The btree_inode will be always in the root cgroup. The cgroup + * writeback can be enabled on regular inodes selectively. + */ new_fl |= S_CGROUPWB; set_mask_bits(&inode->i_flags,