On Jul 9, 2009, at 8:34 AM, Hans Kramer wrote:
Hi,
For some silly reason I have an application that needs to poll for the
existence of a certain file on a NFS share.
(This is done from Sybase ASE ;-)
Now I run into the issue of attribute caching. Turning of the
attribute
cache with the mount option of -o noac easily solves all the issues.
However, it would be nice if we could still use attribute caching and
force to invalidate on-demand the attribute cache.
Since you are only concerned with the existence of a file (and not its
mtime, say). have you considered the new directory cache mount option:
lookupcache=?
I see it's not mentioned in nfs(8) so you should probably look in
recent archives of this mailing list for information.
After a lot of trying, the following solution seems to work for me
now:
(pathname is the test file)
#define _GNU_SOURCE
char *copy = strdup(pathname);
char *path = dirname(copy);
int fd = open(path, O_DIRECTORY);
if (fd >= 0)
close(fd);
free(copy);
return access(pathname, F_OK);
Just opening the parent directory with O_DIRECTORY seems to do the
trick.
My questions: Is this hack going to work under every circumstance or
could it fail in the future with some update. Is there a ioctl call
that
could the the same thing? That is invalidate the parent directory
cache.
Or do I miss something completely ?-)
Thanks in advance
Hans
--
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
--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com
--
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
