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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,
        Johannes Thumshirn <johannes.thumshirn@wdc.com>,
        Filipe Manana <fdmanana@suse.com>,
        David Sterba <dsterba@suse.com>
Subject: [PATCH 5.17 193/225] btrfs: fix leaked plug after failure syncing log on zoned filesystems
Date:   Wed,  4 May 2022 18:47:11 +0200
Message-Id: <20220504153127.459522306@linuxfoundation.org>
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From: Filipe Manana <fdmanana@suse.com>

commit 50ff57888d0b13440e7f4cde05dc339ee8d0f1f8 upstream.

On a zoned filesystem, if we fail to allocate the root node for the log
root tree while syncing the log, we end up returning without finishing
the IO plug we started before, resulting in leaking resources as we
have started writeback for extent buffers of a log tree before. That
allocation failure, which typically is either -ENOMEM or -ENOSPC, is not
fatal and the fsync can safely fallback to a full transaction commit.

So release the IO plug if we fail to allocate the extent buffer for the
root of the log root tree when syncing the log on a zoned filesystem.

Fixes: 3ddebf27fcd3a9 ("btrfs: zoned: reorder log node allocation on zoned filesystem")
CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/btrfs/tree-log.c |    1 +
 1 file changed, 1 insertion(+)

--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -3225,6 +3225,7 @@ int btrfs_sync_log(struct btrfs_trans_ha
 			ret = btrfs_alloc_log_tree_node(trans, log_root_tree);
 			if (ret) {
 				mutex_unlock(&fs_info->tree_root->log_mutex);
+				blk_finish_plug(&plug);
 				goto out;
 			}
 		}