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-rw-r--r--fs/btrfs/tree-log.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index de729acee738..3fc8d854d7fb 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -3110,6 +3110,12 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
log->log_transid = root->log_transid;
root->log_start_pid = 0;
/*
+ * Update or create log root item under the root's log_mutex to prevent
+ * races with concurrent log syncs that can lead to failure to update
+ * log root item because it was not created yet.
+ */
+ ret = update_log_root(trans, log);
+ /*
* IO has been started, blocks of the log tree have WRITTEN flag set
* in their headers. new modifications of the log will be written to
* new positions. so it's safe to allow log writers to go in.
@@ -3128,8 +3134,6 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
mutex_unlock(&log_root_tree->log_mutex);
- ret = update_log_root(trans, log);
-
mutex_lock(&log_root_tree->log_mutex);
if (atomic_dec_and_test(&log_root_tree->log_writers)) {
/* atomic_dec_and_test implies a barrier */