Return-Path: linux-nfs-owner@vger.kernel.org Received: from mx1.redhat.com ([209.132.183.28]:28815 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753277Ab3GIOby (ORCPT ); Tue, 9 Jul 2013 10:31:54 -0400 Date: Tue, 9 Jul 2013 10:31:53 -0400 From: Jeff Layton To: "J. Bruce Fields" Cc: Al Viro , linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 03/12] vfs: rename I_MUTEX_QUOTA now that it's not used for quotas Message-ID: <20130709103153.06e5e502@tlielax.poochiereds.net> In-Reply-To: <20130709142652.GA32574@pad.fieldses.org> References: <1372882356-14168-1-git-send-email-bfields@redhat.com> <1372882356-14168-4-git-send-email-bfields@redhat.com> <20130709065400.5a55a655@tlielax.poochiereds.net> <20130709142652.GA32574@pad.fieldses.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-nfs-owner@vger.kernel.org List-ID: On Tue, 9 Jul 2013 10:26:52 -0400 "J. Bruce Fields" wrote: > On Tue, Jul 09, 2013 at 06:54:00AM -0400, Jeff Layton wrote: > > On Wed, 3 Jul 2013 16:12:27 -0400 > > "J. Bruce Fields" wrote: > > > > > From: "J. Bruce Fields" > > > > > > I_MUTEX_QUOTA is now just being used whenever we want to lock two > > > non-directories. So the name isn't right. I_MUTEX_NONDIR2 isn't > > > especially elegant but it's the best I could think of. > > > > > > Also fix some outdated documentation. > > > > > > Signed-off-by: J. Bruce Fields > > > --- > > > fs/inode.c | 4 ++-- > > > include/linux/fs.h | 9 ++++++--- > > > 2 files changed, 8 insertions(+), 5 deletions(-) > > > > > > diff --git a/fs/inode.c b/fs/inode.c > > > index 942451b..304db4c 100644 > > > --- a/fs/inode.c > > > +++ b/fs/inode.c > > > @@ -988,10 +988,10 @@ void lock_two_nondirectories(struct inode *inode1, struct inode *inode2) > > > { > > > if (inode1 < inode2) { > > > mutex_lock(&inode1->i_mutex); > > > - mutex_lock_nested(&inode2->i_mutex, I_MUTEX_QUOTA); > > > + mutex_lock_nested(&inode2->i_mutex, I_MUTEX_NONDIR2); > > > } else { > > > mutex_lock(&inode2->i_mutex); > > > - mutex_lock_nested(&inode1->i_mutex, I_MUTEX_QUOTA); > > > + mutex_lock_nested(&inode1->i_mutex, I_MUTEX_NONDIR2); > > > } > > > } > > > EXPORT_SYMBOL(lock_two_nondirectories); > > > diff --git a/include/linux/fs.h b/include/linux/fs.h > > > index 3258761..ec88235 100644 > > > --- a/include/linux/fs.h > > > +++ b/include/linux/fs.h > > > @@ -620,10 +620,13 @@ static inline int inode_unhashed(struct inode *inode) > > > * 0: the object of the current VFS operation > > > * 1: parent > > > * 2: child/target > > > - * 3: quota file > > > + * 3: xattr > > > + * 4: second non-directory > > > + * The last is for certain operations (such as rename) which lock two > > > + * non-directories at once. > > > * > > > * The locking order between these classes is > > > - * parent -> child -> normal -> xattr -> quota > > > + * parent -> child -> normal -> xattr -> second non-directory > > > */ > > > enum inode_i_mutex_lock_class > > > { > > > @@ -631,7 +634,7 @@ enum inode_i_mutex_lock_class > > > I_MUTEX_PARENT, > > > I_MUTEX_CHILD, > > > I_MUTEX_XATTR, > > > - I_MUTEX_QUOTA > > > + I_MUTEX_NONDIR2 > > > }; > > > > > > void lock_two_nondirectories(struct inode *, struct inode*); > > > > Ugly name, but I'm not sure what to call it either. Wonder if it would > > make sense to do some sort of SOURCE/TARGET lock class and rearrange > > the code to take that into account? > > You need to order the locks globally somehow (e.g. by ancestor order in > the case of the parent directories)--you can't always take them in the > order source and target, for example, because a rename from A/ into B/ > could then deadlock with a simultaneous rename from B/ into A/. So I > don't think SOURCE and TARGET would work for names. The current names > have a certain logic, but there's probably something more elegant. > > Currently: after these patches a rename of regular a regular file onto > another regular file will take locks on the source and target parents, > and source and target (victim) files. The first two will take PARENT > and CHILD, the second NORMAL and NONDIR2. > Fair enough -- makes sense... > > But, that's just bikeshedding, so... > > > > Acked-by: Jeff Layton -- Jeff Layton