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

[Steve Dickson <SteveD@redhat.com>]

On 03/07/2012 03:07 PM, Chuck Lever wrote:
> 
> On Mar 7, 2012, at 2:56 PM, 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.
> 
> Does this address https://bugzilla.linux-nfs.org/show_bug.cgi?id=224 ?
Yes, I believe so. It also addresses 
    https://bugzilla.redhat.com/show_bug.cgi?id=800335

I guess I make this fix back in the RHEL4 days and the
patch never made into upstream. 

steved.

> 
>> 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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>