[sheepdog] [PATCH v5] sheep: implement a correct mutex of a base directory

[MORITA Kazutaka]

At Tue, 30 Apr 2013 09:14:19 +0900,
Hitoshi Mitake wrote:
> 
> Current lockf() usage in lock_base_dir() is invalid bacause sheep
> calls daemon(3) after the lockf(). daemon(3) forks internally and a
> parent process exits immediately. In a case of sheep, daemon() must be
> called after locking base dir so the lock owner, parent process, exits
> and the lock will be released even though the child process is
> running. This is the reason current lock_base_dir() doesn't work
> well. And it causes writing logs to sheep.log from multiple
> sheeps. This phenomenon is very confusing and should be avoided.
> 
> This patch implement custom function for daemonizing,
> lock_and_daemon(). And mutex of base directory is done in
> it. lock_and_daemon() does mutex between fork() and closing fd 0, 1,
> and 2, so it can report the failure of mutexing base directory to
> stderr.
> 
> Signed-off-by: Hitoshi Mitake <mitake.hitoshi at lab.ntt.co.jp>
> ---
> v5: update the commit log
> 
> v4: also lock file when sheep runs in foreground
> 
> v3: implement custom function for daemonizing and do mutex in it
> 
> v2: call exit_handler() from crash_handler() too
> 
>  sheep/sheep.c      |   61 +++++++++++++++++++++++++++++++++++++++++++++++++++-
>  sheep/sheep_priv.h |    1 +
>  sheep/store.c      |    4 ++--
>  3 files changed, 63 insertions(+), 3 deletions(-)

Applied, thanks!

Kazutaka