Messages in this thread | | | Date | Wed, 20 Jun 2007 14:23:30 +0530 | From | "Bharata B Rao" <> | Subject | Re: [RFC PATCH 2/4] Mount changes to support union mount. |
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(replying from a different ID as you didn't copy me on reply)
On 6/20/07, Jan Blunck <jblunck@suse.de> wrote: > On Wed, 20 Jun 2007 11:22:41 +0530, Bharata B Rao wrote: > > > +/* > > + * When propagating mount events to peer group, this is called under > > + * vfsmount_lock. Hence using GFP_ATOMIC for kmalloc here. > > + * TODO: Can we use a separate kmem cache for union_mount ? > > + */ > > +struct union_mount *alloc_union_mount(struct vfsmount *src_mnt, > > + struct dentry *src_dentry, struct vfsmount *dst_mnt, > > + struct dentry *dst_dentry) > > +{ > > + struct union_mount *u; > > + u = kmalloc(sizeof(struct union_mount), GFP_ATOMIC); > > + if (!u) > > + return u; > > + u->dst_mnt = mntget(dst_mnt); > > + u->dst_dentry = dget(dst_dentry); > > + u->src_mnt = src_mnt; > > + u->src_dentry = dget(src_dentry); > > + INIT_LIST_HEAD(&u->hash); > > + INIT_LIST_HEAD(&u->list); > > + return u; > > +} > > Hmm, you pin the dentries in memory until umount. This isn't good. Besides > that this doesn't work with file systems that do invalidate their > dentries. The file system must have a chance to replace the dentry in the > union structure.
Yes, both top level and next level dentries are pinned until umount of the upper layer. I was thinking if we could prune these from prune_dcache(). What do you think ?
Ok, I haven't thought about filesystem invalidating the dentries. Yet to understand the dentry invalidation, but would filesystem invalidate an inuse dentry ?
Regards, Bharata. -- "Men come and go but mountains remain" -- Ruskin Bond. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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