On Sat, 2008-03-22 at 04:11 +0000, Al Viro wrote: > On Sat, Mar 22, 2008 at 03:49:50AM +0000, Al Viro wrote: > > > Shifting increment from mnt_set_mountpoint() and commit_tree() > > to theirs callers and collapsing where possible, we get the > following: > > * decrement in release_mounts() when resetting ->mnt_parent > > * increment in propagate_mnt() after call of > mnt_set_mountpoint() > > * decrement in attach_recursive_mnt() in the loop calling > > commit_tree() for clones (on mountpoint of each clone). > > * increment in umount_tree() at the point where we update > d_mounted. > > ... except that it'd give a leak in case of mount to shared mountpoint > failing halfway through - we'll get double increments since > umount_tree() > would hit the mountpoints of cloned trees with extra increment, even > though > reference from root of cloned to its mountpoint is _already_ a ghost. > OTOH, we probably don't want to bother with counting those anyway - > i.e. > it's simply a bad definition and the right one would be along the > lines of > "number of vfsmounts that are doomed to be eaten by release_mounts() > and > that have ->mnt_parent pointing to us". IOW, dropping the 2nd and 3rd > in the above would do the right thing - anything chewed by > umount_tree() > *will* go to release_mounts() and ones in flight are what we are > interested > in... By not accounting for the ghost reference created in propagate_mnt(), i.e case 2 and 3; the race is still on with shrink_mounts. But I think, you are right. We don't want the shrink_mounts and friends to think that the mounts are available to be purged, by accounting them into mnt_ghosts. RP -- 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
