linux-kernel - [PATCH 5.16 007/200] btrfs: add back missing dirty page rate limiting to defrag

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Date:   Mon, 31 Jan 2022 11:54:30 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Qu Wenruo <wqu@...e.com>,
        Filipe Manana <fdmanana@...e.com>,
        David Sterba <dsterba@...e.com>
Subject: [PATCH 5.16 007/200] btrfs: add back missing dirty page rate limiting to defrag

From: Filipe Manana <fdmanana@...e.com>

commit 3c9d31c715948aaff0ee6d322a91a2dec07770bf upstream.

A defrag operation can dirty a lot of pages, specially if operating on
the entire file or a large file range. Any task dirtying pages should
periodically call balance_dirty_pages_ratelimited(), as stated in that
function's comments, otherwise they can leave too many dirty pages in
the system. This is what we did before the refactoring in 5.16, and
it should have remained, just like in the buffered write path and
relocation. So restore that behaviour.

Fixes: 7b508037d4cac3 ("btrfs: defrag: use defrag_one_cluster() to implement btrfs_defrag_file()")
CC: stable@...r.kernel.org # 5.16
Reviewed-by: Qu Wenruo <wqu@...e.com>
Signed-off-by: Filipe Manana <fdmanana@...e.com>
Signed-off-by: David Sterba <dsterba@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/btrfs/ioctl.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1553,6 +1553,7 @@ int btrfs_defrag_file(struct inode *inod
 	}
 
 	while (cur < last_byte) {
+		const unsigned long prev_sectors_defragged = sectors_defragged;
 		u64 cluster_end;
 
 		/* The cluster size 256K should always be page aligned */
@@ -1584,6 +1585,10 @@ int btrfs_defrag_file(struct inode *inod
 				cluster_end + 1 - cur, extent_thresh,
 				newer_than, do_compress,
 				&sectors_defragged, max_to_defrag);
+
+		if (sectors_defragged > prev_sectors_defragged)
+			balance_dirty_pages_ratelimited(inode->i_mapping);
+
 		btrfs_inode_unlock(inode, 0);
 		if (ret < 0)
 			break;