-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Ram wrote: > On Tue, 2005-02-01 at 15:21, J. Bruce Fields wrote: > >>On Tue, Jan 25, 2005 at 01:07:12PM -0800, Ram wrote: >> >>>If there exists a private subtree in a larger shared subtree, what >>>happens when the larger shared subtree is rbound to some other place? >>>Is a new private subtree created in the new larger shared subtree? or >>>will that be pruned out in the new larger subtree? >> >>"mount --rbind" will always do at least all the mounts that it did >>before the introduction of shared subtrees--so certainly it will copy >>private subtrees along with shared ones. (Since subtrees are private by >>default, anything else would make --rbind do nothing by default.) My >>understanding of Viro's RFC is that the new subtree will have no >>connection with the preexisting private subtree (we want private >>subtrees to stay private), but that the new copy will end up with >>whatever propagation the target of the "mount --rbind" had. (So the >>addition of the copy of the private subtree to the target vfsmount will >>be replicated on any vfsmount that the target vfsmount propogates to, >>and those copies will propagate among themselves in the same way that >>the copies of the target vfsmount propagate to each other.) > > > ok. that makes sense. As you said the private subtree shall get copied > to the new location, however propogations wont be set in either > directions. However I have a rather unusual requirement which forces > multiple rbind of a shared subtree within the same shared subtree. > > I did the calculation and found that the tree simply explodes with > vfsstructs. If I mark a subtree within the larger shared tree as > private, then the number of vfsstructs grows linearly O(n). However if > there was a way of marking a subtree within the larger shared tree as > unclonable than the increase in number of vfsstruct is constant. > > What I am essentially driving at is, can we add another feature which > allows me to mark a subtree as unclonable? > > > Read below to see how the tree explodes: > > to run you through an example: > > (In case the tree pictures below gets garbled, it can also be seen at > http://www.sudhaa.com/~ram/readahead/sharedsubtree/subtree ) > > step 1: > lets say the root tree has just two directories with one vfsstruct. > root > / \ > tmp usr > All I want is to be able to see the entire root tree > (but not anything under /root/tmp) to be viewable under /root/tmp/m* > > step2: > mount --make-shared /root > > mkdir -p /tmp/m1 > > mount --rbind /root /tmp/m1 > > the new tree now looks like this: > > root > / \ > tmp usr > / > m1 > / \ > tmp usr > / > m1 > > it has two vfsstructs > > step3: > mkdir -p /tmp/m2 > mount --rbind /root /tmp/m2
At this step, you probably shouldn't be using --rbind, but --bind instead to only bind a copy of the root vfsmount, so it now looks like: > root > / \ > tmp usr > / \ > m1 m2 > / \ / \ > tmp usr tmp usr > / \ / \ > m1 m2 m1 m2 - -- Mike Waychison Sun Microsystems, Inc. 1 (650) 352-5299 voice 1 (416) 202-8336 voice ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NOTICE: The opinions expressed in this email are held by me, and may not represent the views of Sun Microsystems, Inc. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.5 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFCAS3ndQs4kOxk3/MRAm/qAJ0awCE49/g+HhMdX0MBZnFLSp2IjACgj5EQ El+YLq25hQeDAt9Y92nqoAU= =so+d -----END PGP SIGNATURE----- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
