Re: [PATCH 1/1] exportfs: Stop racing exportfs on clusters

["J. Bruce Fields" <bfields@fieldses.org>]

On Wed, Mar 07, 2012 at 02:56:30PM -0500, Steve Dickson wrote:
> This problem can occur when multiple cluster services fail over
> at the same time, causing missing high-available exports.
> Having a lot of nfs-exports will trigger this issue easier.

Isn't the locking in support/export/xtab.c supposed to take care of
this?

I may be confused--I forget what all these files are for....

--b.

> 
> Signed-off-by: Steve Dickson <steved@redhat.com>
> ---
>  support/include/exportfs.h |    4 ++++
>  utils/exportfs/exportfs.c  |   24 ++++++++++++++++++++++++
>  2 files changed, 28 insertions(+), 0 deletions(-)
> 
> diff --git a/support/include/exportfs.h b/support/include/exportfs.h
> index 01e87dd..99916e5 100644
> --- a/support/include/exportfs.h
> +++ b/support/include/exportfs.h
> @@ -32,6 +32,10 @@ enum {
>  	FSLOC_STUB
>  };
>  
> +#ifndef EXP_LOCKFILE
> +#define EXP_LOCKFILE "/var/lib/nfs/export-lock"
> +#endif
> +
>  typedef struct mclient {
>  	struct mclient *	m_next;
>  	char *			m_hostname;
> diff --git a/utils/exportfs/exportfs.c b/utils/exportfs/exportfs.c
> index 7432a65..769d438 100644
> --- a/utils/exportfs/exportfs.c
> +++ b/utils/exportfs/exportfs.c
> @@ -16,6 +16,7 @@
>  #include <sys/stat.h>
>  #include <sys/vfs.h>
>  #include <sys/stat.h>
> +#include <sys/file.h>
>  #include <unistd.h>
>  #include <stdbool.h>
>  #include <stdlib.h>
> @@ -44,6 +45,23 @@ static void	validate_export(nfs_export *exp);
>  static int	matchhostname(const char *hostname1, const char *hostname2);
>  static void	export_d_read(const char *dname);
>  
> +static const char *lockfile = EXP_LOCKFILE;
> +static int _lockfd = -1;
> +
> +void 
> +grab_lockfile()
> +{
> +	_lockfd = open(lockfile, O_CREAT|O_RDWR, 0666);
> +	if (_lockfd != -1) 
> +		lockf(_lockfd, F_LOCK, 0);
> +}
> +void 
> +release_lockfile()
> +{
> +	if (_lockfd != -1)
> +		lockf(_lockfd, F_ULOCK, 0);
> +}
> +
>  int
>  main(int argc, char **argv)
>  {
> @@ -129,6 +147,12 @@ main(int argc, char **argv)
>  			return 0;
>  		}
>  	}
> +	/*
> +	 * Serialize things as best we can
> +	 */
> +	grab_lockfile();
> +	atexit(release_lockfile);
> +
>  	if (f_export && ! f_ignore) {
>  		export_read(_PATH_EXPORTS);
>  		export_d_read(_PATH_EXPORTS_D);
> -- 
> 1.7.7.6
> 
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