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From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Song Liu <song@kernel.org>, Hans de Goede <hdegoede@redhat.com>,
	Richard Weinberger <richard@nod.at>,
	Minchan Kim <minchan@kernel.org>,
	Johannes Thumshirn <Johannes.Thumshirn@wdc.com>,
	linux-mtd@lists.infradead.org, dm-devel@redhat.com,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	drbd-dev@lists.linbit.com, linux-raid@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	cgroups@vger.kernel.org,
	Johannes Thumshirn <johannes.thumshirn@wdc.com>
Subject: [PATCH 07/12] bdi: remove BDI_CAP_CGROUP_WRITEBACK
Date: Tue, 15 Sep 2020 17:18:24 +0200	[thread overview]
Message-ID: <20200915151829.1767176-8-hch@lst.de> (raw)
In-Reply-To: <20200915151829.1767176-1-hch@lst.de>

Just checking SB_I_CGROUPWB for cgroup writeback support is enough.
Either the file system allocates its own bdi (e.g. btrfs), in which case
it is known to support cgroup writeback, or the bdi comes from the block
layer, which always supports cgroup writeback.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 block/blk-core.c            | 1 -
 fs/btrfs/disk-io.c          | 1 -
 include/linux/backing-dev.h | 8 +++-----
 3 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 865d39e5be2b28..1cc4fa6bc7fe1f 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -538,7 +538,6 @@ struct request_queue *blk_alloc_queue(int node_id)
 	if (!q->stats)
 		goto fail_stats;
 
-	q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK;
 	q->node = node_id;
 
 	atomic_set(&q->nr_active_requests_shared_sbitmap, 0);
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 047934cea25efa..e24927bddd5829 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3091,7 +3091,6 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 		goto fail_sb_buffer;
 	}
 
-	sb->s_bdi->capabilities |= BDI_CAP_CGROUP_WRITEBACK;
 	sb->s_bdi->ra_pages *= btrfs_super_num_devices(disk_super);
 	sb->s_bdi->ra_pages = max(sb->s_bdi->ra_pages, SZ_4M / PAGE_SIZE);
 
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 0b06b2d26c9aa3..52583b6f2ea05d 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -123,7 +123,6 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
  * BDI_CAP_NO_ACCT_WB:     Don't automatically account writeback pages
  * BDI_CAP_STRICTLIMIT:    Keep number of dirty pages below bdi threshold.
  *
- * BDI_CAP_CGROUP_WRITEBACK: Supports cgroup-aware writeback.
  * BDI_CAP_SYNCHRONOUS_IO: Device is so fast that asynchronous IO would be
  *			   inefficient.
  */
@@ -233,9 +232,9 @@ int inode_congested(struct inode *inode, int cong_bits);
  * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
  * @inode: inode of interest
  *
- * cgroup writeback requires support from both the bdi and filesystem.
- * Also, both memcg and iocg have to be on the default hierarchy.  Test
- * whether all conditions are met.
+ * Cgroup writeback requires support from the filesystem.  Also, both memcg and
+ * iocg have to be on the default hierarchy.  Test whether all conditions are
+ * met.
  *
  * Note that the test result may change dynamically on the same inode
  * depending on how memcg and iocg are configured.
@@ -247,7 +246,6 @@ static inline bool inode_cgwb_enabled(struct inode *inode)
 	return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
 		cgroup_subsys_on_dfl(io_cgrp_subsys) &&
 		bdi_cap_account_dirty(bdi) &&
-		(bdi->capabilities & BDI_CAP_CGROUP_WRITEBACK) &&
 		(inode->i_sb->s_iflags & SB_I_CGROUPWB);
 }
 
-- 
2.28.0


  parent reply	other threads:[~2020-09-15 22:40 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-15 15:18 bdi cleanups v5 Christoph Hellwig
2020-09-15 15:18 ` [PATCH 01/12] fs: remove the unused SB_I_MULTIROOT flag Christoph Hellwig
2020-09-15 15:18 ` [PATCH 02/12] drbd: remove dead code in device_to_statistics Christoph Hellwig
2020-09-15 15:18 ` [PATCH 03/12] drbd: remove RB_CONGESTED_REMOTE Christoph Hellwig
2020-09-15 15:18 ` [PATCH 04/12] bdi: initialize ->ra_pages and ->io_pages in bdi_init Christoph Hellwig
2020-09-15 15:18 ` [PATCH 05/12] md: update the optimal I/O size on reshape Christoph Hellwig
2020-09-15 15:18 ` [PATCH 06/12] block: lift setting the readahead size into the block layer Christoph Hellwig
2020-09-15 15:18 ` Christoph Hellwig [this message]
2020-09-15 15:18 ` [PATCH 08/12] bdi: remove BDI_CAP_SYNCHRONOUS_IO Christoph Hellwig
2020-09-15 15:18 ` [PATCH 09/12] mm: use SWP_SYNCHRONOUS_IO more intelligently Christoph Hellwig
2020-09-15 15:18 ` [PATCH 10/12] bdi: replace BDI_CAP_STABLE_WRITES with a queue and a sb flag Christoph Hellwig
2020-09-15 15:18 ` [PATCH 11/12] bdi: invert BDI_CAP_NO_ACCT_WB Christoph Hellwig
2020-09-15 15:18 ` [PATCH 12/12] bdi: replace BDI_CAP_NO_{WRITEBACK,ACCT_DIRTY} with a single flag Christoph Hellwig
  -- strict thread matches above, loose matches on Subject: below --
2020-09-10 14:48 bdi cleanups v4 Christoph Hellwig
2020-09-10 14:48 ` [PATCH 07/12] bdi: remove BDI_CAP_CGROUP_WRITEBACK Christoph Hellwig
2020-09-16  9:28   ` David Sterba
2020-09-17  9:36   ` Jan Kara

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