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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, Nikolay Borisov <nborisov@suse.com>,
        David Sterba <dsterba@suse.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 31/71] btrfs: Remove extraneous extent_buffer_get from tree_mod_log_rewind
Date:   Fri, 11 Sep 2020 14:46:15 +0200
Message-Id: <20200911122506.483895838@linuxfoundation.org>
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From: Nikolay Borisov <nborisov@suse.com>

[ Upstream commit 24cee18a1c1d7c731ea5987e0c99daea22ae7f4a ]

When a rewound buffer is created it already has a ref count of 1 and the
dummy flag set. Then another ref is taken bumping the count to 2.
Finally when this buffer is released from btrfs_release_path the extra
reference is decremented by the special handling code in
free_extent_buffer.

However, this special code is in fact redundant sinca ref count of 1 is
still correct since the buffer is only accessed via btrfs_path struct.
This paves the way forward of removing the special handling in
free_extent_buffer.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/btrfs/ctree.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 78d4c8c22b4ac..406ae49baa076 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1360,7 +1360,6 @@ tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
 	btrfs_tree_read_unlock_blocking(eb);
 	free_extent_buffer(eb);
 
-	extent_buffer_get(eb_rewin);
 	btrfs_tree_read_lock(eb_rewin);
 	__tree_mod_log_rewind(fs_info, eb_rewin, time_seq, tm);
 	WARN_ON(btrfs_header_nritems(eb_rewin) >
-- 
2.25.1