On Mon, Mar 30, 2009 at 7:29 PM, Jeff Layton <jlayton@xxxxxxxxxx> wrote: > On Mon, 30 Mar 2009 15:07:23 -0500 > Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx> wrote: > >> On Mon, Mar 30, 2009 at 12:45 PM, Jeff Layton <jlayton@xxxxxxxxxx> wrote: >> > On Mon, 30 Mar 2009 10:57:32 -0500 >> > Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx> wrote: >> >> >> >> Jeff, >> >> >> >> Thanks. Looking into it. I am trying to figure out the need/necessity >> >> for cifs_lookup to call lookup_instanitate_flip. >> >> lookup_instantiate_filp does call dentry_open and if cifs_lookup does >> >> not call lookup_instantiate_flip, >> >> nameidata_to_filp will call dentry_open. >> >> So I am not sure what we loose if dentry_open does not get called >> >> between lookup_hash and nameidata_to_flip >> >> because of an error between those two calls, specifically how will the >> >> cause of open file getting closed on the >> >> server will be served if there was an in-betwen error by calling >> >> lookup_instantiate_filp. >> >> >> > >> > I'm not certain since I haven't tested your patch, but you may end up >> > with an inode refcount leak (aka Busy inodes after umount...). You're >> > doing an open on the file in the lookup and I think that increases the >> > refcount of the inode (i_count). Eventually, that inode gets "put" when >> > you close the file. In the error situation described above though, that >> > put will never occur. As far as the VFS is concerned, the file was >> > never actually opened, so it doesn't need to issue a fput(). >> >> We would still be in do_flip_open and so if there is an error, while exiting >> release_open_intent would get called which would so the cleanup i.e. >> call fput(). > > release_open_intent only calls fput if there is a filp set in the > open_intent info. With your patch, you won't have one. > > Well...you'll have an empty filp, but I'm not sure it'll have all of > the fields that are needed to actually make release_open_intent call > fput(). In particular, I don't think f_path.dentry will be set. > >> Let me introduce an error in between to verify whether the data structures >> are cleaned up, such as i_count of an inode. >> >> > >> > Properly cleaning up the references is the main reason to make sure >> > that you pass the filp back to the caller here. Closing the open file >> > on the server is also a nice side benefit since that could block the >> > granting of oplocks and such. >> > >> >> I think caller is oblivious to the speed-up mechanism that cifs is attempting >> by taking advantage of lookup intents to reduce network traffic. >> > > Right -- and that's a problem since it won't clean up the references > unless it knows this. > > -- > Jeff Layton <jlayton@xxxxxxxxxx> > OK, let me make those changes and I will re-post the patch on a different thread with appropriate subject line. Regards, Shirish -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
