On 03/12/2012 01:23 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. > > https://bugzilla.linux-nfs.org/show_bug.cgi?id=224 > > Signed-off-by: Steve Dickson <steved@xxxxxxxxxx> Committed... steved. > --- > support/include/exportfs.h | 4 ++++ > utils/exportfs/exportfs.c | 41 +++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 45 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..7326802 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 +45,39 @@ 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; > + > +/* > + * If we aren't careful, changes made by exportfs can be lost > + * when multiple exports process run at once: > + * > + * exportfs process 1 exportfs process 2 > + * ------------------------------------------ > + * reads etab version A reads etab version A > + * adds new export B adds new export C > + * writes A+B writes A+C > + * > + * The locking in support/export/xtab.c will prevent mountd from > + * seeing a partially written version of etab, and will prevent > + * the two writers above from writing simultaneously and > + * corrupting etab, but to prevent problems like the above we > + * need these additional lockfile() routines. > + */ > +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 +163,13 @@ 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); -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
