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Each file actually has a lock count associated with it. This allows nested calls by a task to acquire a file lock; each of those calls must be matched with a call to fs_funlockfile().
Listing 10-4 Example file lock usage
L10-4(1) fs_flockfile() will block the calling task until the file is available. If the task must write to the file only if no other task is currently accessing it, the non-blocking function fs_funlockfile() can be used.