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Subject: [PATCH 5/9] cephfs: don't set/clear bdi_congestion
From:   NeilBrown <neilb@suse.de>
To:     Andrew Morton <akpm@linux-foundation.org>,
        Jaegeuk Kim <jaegeuk@kernel.org>, Chao Yu <chao@kernel.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>,
        Ryusuke Konishi <konishi.ryusuke@gmail.com>,
        "Darrick J. Wong" <djwong@kernel.org>,
        Philipp Reisner <philipp.reisner@linbit.com>,
        Lars Ellenberg <lars.ellenberg@linbit.com>,
        Paolo Valente <paolo.valente@linaro.org>,
        Jens Axboe <axboe@kernel.dk>
Cc:     linux-mm@kvack.org, linux-nilfs@vger.kernel.org,
        linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net, linux-ext4@vger.kernel.org,
        ceph-devel@vger.kernel.org, drbd-dev@lists.linbit.com,
        linux-kernel@vger.kernel.org, linux-block@vger.kernel.org
Date:   Thu, 27 Jan 2022 13:46:29 +1100
Message-ID: <164325158958.29787.8840004338500709466.stgit@noble.brown>
In-Reply-To: <164325106958.29787.4865219843242892726.stgit@noble.brown>
References: <164325106958.29787.4865219843242892726.stgit@noble.brown>
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Precedence: bulk

The bdi congestion framework is no-longer used - writeback uses other
mechanisms to manage throughput.

So remove calls to set_bdi_congested() and clear_bdi_congested(), and
remove the writeback_count which is used only to guide the setting and
clearing.

The congestion_kb mount option is no longer meaningful, but as it is
visible to user-space, removing it needs more consideration.

Signed-off-by: NeilBrown <neilb@suse.de>
---
 fs/ceph/addr.c  |   27 ---------------------------
 fs/ceph/super.c |    2 --
 fs/ceph/super.h |    2 --
 3 files changed, 31 deletions(-)

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index c98e5238a1b6..9147667f8cd5 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -57,11 +57,6 @@
  * accounting is preserved.
  */
 
-#define CONGESTION_ON_THRESH(congestion_kb) (congestion_kb >> (PAGE_SHIFT-10))
-#define CONGESTION_OFF_THRESH(congestion_kb)				\
-	(CONGESTION_ON_THRESH(congestion_kb) -				\
-	 (CONGESTION_ON_THRESH(congestion_kb) >> 2))
-
 static int ceph_netfs_check_write_begin(struct file *file, loff_t pos, unsigned int len,
 					struct folio *folio, void **_fsdata);
 
@@ -561,10 +556,6 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
 	dout("writepage %p page %p index %lu on %llu~%llu snapc %p seq %lld\n",
 	     inode, page, page->index, page_off, len, snapc, snapc->seq);
 
-	if (atomic_long_inc_return(&fsc->writeback_count) >
-	    CONGESTION_ON_THRESH(fsc->mount_options->congestion_kb))
-		set_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
-
 	req = ceph_osdc_new_request(osdc, &ci->i_layout, ceph_vino(inode), page_off, &len, 0, 1,
 				    CEPH_OSD_OP_WRITE, CEPH_OSD_FLAG_WRITE, snapc,
 				    ceph_wbc.truncate_seq, ceph_wbc.truncate_size,
@@ -621,10 +612,6 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
 	ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
 	ceph_put_snap_context(snapc);  /* page's reference */
 
-	if (atomic_long_dec_return(&fsc->writeback_count) <
-	    CONGESTION_OFF_THRESH(fsc->mount_options->congestion_kb))
-		clear_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
-
 	return err;
 }
 
@@ -704,12 +691,6 @@ static void writepages_finish(struct ceph_osd_request *req)
 			BUG_ON(!page);
 			WARN_ON(!PageUptodate(page));
 
-			if (atomic_long_dec_return(&fsc->writeback_count) <
-			     CONGESTION_OFF_THRESH(
-					fsc->mount_options->congestion_kb))
-				clear_bdi_congested(inode_to_bdi(inode),
-						    BLK_RW_ASYNC);
-
 			ceph_put_snap_context(detach_page_private(page));
 			end_page_writeback(page);
 			dout("unlocking %p\n", page);
@@ -952,14 +933,6 @@ static int ceph_writepages_start(struct address_space *mapping,
 			dout("%p will write page %p idx %lu\n",
 			     inode, page, page->index);
 
-			if (atomic_long_inc_return(&fsc->writeback_count) >
-			    CONGESTION_ON_THRESH(
-				    fsc->mount_options->congestion_kb)) {
-				set_bdi_congested(inode_to_bdi(inode),
-						  BLK_RW_ASYNC);
-			}
-
-
 			pages[locked_pages++] = page;
 			pvec.pages[i] = NULL;
 
diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index bf79f369aec6..b2f38af9fca8 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -801,8 +801,6 @@ static struct ceph_fs_client *create_fs_client(struct ceph_mount_options *fsopt,
 	fsc->filp_gen = 1;
 	fsc->have_copy_from2 = true;
 
-	atomic_long_set(&fsc->writeback_count, 0);
-
 	err = -ENOMEM;
 	/*
 	 * The number of concurrent works can be high but they don't need
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 67f145e1ae7a..fc58adf1d36a 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -120,8 +120,6 @@ struct ceph_fs_client {
 
 	struct ceph_mds_client *mdsc;
 
-	atomic_long_t writeback_count;
-
 	struct workqueue_struct *inode_wq;
 	struct workqueue_struct *cap_wq;