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Subject: [PATCH 0/3] remove dependence of inode_congested()
From:   NeilBrown <neilb@suse.de>
To:     Andrew Morton <akpm@linux-foundation.org>,
        Jeff Layton <jlayton@kernel.org>,
        Ilya Dryomov <idryomov@gmail.com>,
        Miklos Szeredi <miklos@szeredi.hu>,
        Trond Myklebust <trond.myklebust@hammerspace.com>,
        Anna Schumaker <anna.schumaker@netapp.com>
Cc:     linux-mm@kvack.org, linux-nfs@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, ceph-devel@vger.kernel.org,
        linux-kernel@vger.kernel.org
Date:   Mon, 31 Jan 2022 15:03:53 +1100
Message-ID: <164360127045.4233.2606812444285122570.stgit@noble.brown>
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Miklos pointed out that the filesystems which set the bdi congestion
flags do gain some value from that, and simply removing the code is not
appropriate.

Specifically, readahead and/or writeback are skipped when the congestion
flags are set.

We can mostly move this skipping into the filesystem.
->readahead can do nothing if reads are congested.
->writepage and ->wrtepages can do nothing for WB_SYNC_NONE if writes
  are congested.

Currently only *some* WB_SYNC_NONE writes are skipped due to congestion.
Those from sync_file_range() and those used for page migration are not.
Also, shrink_page_list() will now cause PageActive to be set if
->writepage skips due to congestion.

I don't expect these changes to be a problem, but I have no experience
to base that on.

Review/comments most welcome,

Thanks,
NeilBrown


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NeilBrown (3):
      fuse: remove reliance on bdi congestion
      nfs: remove reliance on bdi congestion
      ceph: remove reliance on bdi congestion


 fs/ceph/addr.c            | 22 +++++++++++++---------
 fs/ceph/super.c           |  1 +
 fs/ceph/super.h           |  1 +
 fs/nfs/write.c            | 12 ++++++++++--
 include/linux/nfs_fs_sb.h |  1 +
 5 files changed, 26 insertions(+), 11 deletions(-)

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