On Wed, Apr 30, 2014 at 01:57:05PM -0700, Linus Torvalds wrote: > On Wed, Apr 30, 2014 at 1:38 PM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > > > > We do not (and cannot) call dentry_kill() with rcu_read_lock held - it can > > trigger any amount of IO, for one thing. We can take it around the > > couple of places where do that spin_unlock(&dentry->d_lock) (along with > > setting DCACHE_RCUACCESS) - that's what I'd been refering to. > > Just the last spin_unlock() would be the case that matters, if the > spin_unlock() is done on something that could be freed immediately and > the lock protects and is inside the entity that gets freed. *nod* There are two such spin_unlock (handover from shrink_dentry_list() to dput() and the opposite one), but they are all that needs protection - ->d_flags update is outside the rcu-critical area. I really wonder if we *can* get there without DCACHE_RCUACCESS having been set, though; dentry would have to be * picked into shrink list (i.e. have had zero refcount at some point) * never had been through __d_rehash() shrink_dentry_list() definitely counts on that being impossible, and it probably is, but I'm feeling seriously paranoid about the whole area. I'll finish grepping through the tree and probably drop setting DCACHE_RCUACCESS from the patch - either that, or set it in d_shrink_add() it it turns out that it is possible and shrink_dentry_list() is fucked... Tests seem to be running fine so far... > > BTW, is there any convenient > > way to tell git commit --amend to update the commit date? Something > > like --date=now would be nice, but it isn't accepted... > > --date="$(date)" works. Thanks... -- 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
