Hi Lorenzo, > Thank you for the explanation. This looks promising. > One issue I've noticed, which might be related to flock, is that on occasion, > in one of the concurrent threads, > open( , O_CREAT|O_WRONLY, 0755) will return -1 with errno "Permission > denied". I'm running as root and the file and parent > directory mode are 0755. When using the same test with the ext3 file system I > don't get this error.
Hmmm. Could you do a echo 1 > /proc/sys/pvfs2/debug, run your tests and send the dmesg logs to me off-list if it is too big? How reproducible is this error? Perhaps you could share this program for us. I doubt this is related to locking, I suspect it could be yet another permissions issue with the VFS code :( Thanks, Murali > Lorenzo > > From: Murali Vilayannur <[EMAIL PROTECTED]> > To: Lorenzo Pinto <[EMAIL PROTECTED]> > Cc: [email protected] > Subject: Re: [Pvfs2-users] VFS clients on a single machine appear to > work with flock > Date: Mon, 10 Jul 2006 11:27:54 -0500 (CDT) > > Hi Lorenzo, > > > I realize that flock and other flavors of advisory locking are not > > officially supported by PVFS through VFS. However, with my setup of one > > PVFS client machine, four I/O servers, and one metadata server > > (different from the client machine), it does appear that multiple > > applications and/or threads, on the one client machine, calling flock on > > a pvfs2 file-system file behave correctly. This can be tested using the > > (FC5) flock application. As expected, this does not work with multiple > > client machines. > > A generic flock() mechanism is implemented in the VFS layer > fs/locks.c. Network file systems that allow clients to run on other > physically separate machines require more code than what the VFS layer > does to serialize readers.writers on a single node. > We havent done that yet for PVFS and hence it wont work on multiple client > nodes as you indicate below. > > > Now the question: Is the behavior I'm observing by design, or is it > > some coincidence that should not be relied upon. > > So it should work as long as they are all threads/processes on the same > machine/running on the same kernel. > Thanks, > Murali > > > > > > _______________________________________________ Pvfs2-users mailing list [email protected] http://www.beowulf-underground.org/mailman/listinfo/pvfs2-users
