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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Filipe Manana <fdmanana@suse.com>,
        Josef Bacik <josef@toxicpanda.com>,
        David Sterba <dsterba@suse.com>
Subject: [PATCH 4.19 348/361] btrfs: reset max_extent_size properly
Date:   Sun, 11 Nov 2018 14:21:35 -0800
Message-Id: <20181111221701.304788779@linuxfoundation.org>
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References: <20181111221619.915519183@linuxfoundation.org>
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4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Josef Bacik <josef@toxicpanda.com>

commit 21a94f7acf0f748599ea552af5d9ee7d7e41c72f upstream.

If we use up our block group before allocating a new one we'll easily
get a max_extent_size that's set really really low, which will result in
a lot of fragmentation.  We need to make sure we're resetting the
max_extent_size when we add a new chunk or add new space.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/btrfs/extent-tree.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4530,6 +4530,7 @@ static int do_chunk_alloc(struct btrfs_t
 			goto out;
 	} else {
 		ret = 1;
+		space_info->max_extent_size = 0;
 	}
 
 	space_info->force_alloc = CHUNK_ALLOC_NO_FORCE;
@@ -6431,6 +6432,7 @@ static int btrfs_free_reserved_bytes(str
 		space_info->bytes_readonly += num_bytes;
 	cache->reserved -= num_bytes;
 	space_info->bytes_reserved -= num_bytes;
+	space_info->max_extent_size = 0;
 
 	if (delalloc)
 		cache->delalloc_bytes -= num_bytes;