On Mon, 2007-02-19 at 23:23 +0000, Jörn Engel wrote: > On Mon, 19 February 2007 17:05:55 -0600, Dave Kleikamp wrote: > > > > It'd be nice if you could drop s_w_mutex when the garbage collector > > calls i_get(). > > Not possible. Garbage collection only happens when space is getting > tight. At that moment all writes must be serialized or this race will > be the least of my problems. :( > > > Otherwise, you may be able to call ilookup5_nowait() in the garbage > > collector, and skip that inode if I_LOCK is set. > > Also not possible. I cannot skip that inode, or again this race will be > a minor problem. The inode exists on the medium and I must get it by > some means. Re-reading it from the medium is fine, writing is not and > waiting for the write to happen brings me back to square one. Okay, I get it now. You've got more constraints than I initially realized. > It is a nasty problem that has been haunting me for about a year now. > For a while I tried ilookup5_nowait() and just used the inode in spite > of the lock. But that will explode spectacularly when racing against > generic_drop_inode(). You've obviously given this a lot more thought that I have, but this sounds like something that has possibilities. You couldn't implement your own drop_inode method that does better locking against the garbage collector? > Double-caching or a common lock seem to be the only solutions. > > Jörn > -- David Kleikamp IBM Linux Technology Center - 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
