On Sat, Nov 27, 2010 at 08:56:03PM +1100, Nick Piggin wrote: > This reverts commit 3825bdb7ed920845961f32f364454bee5f469abb. > > Patch is broken, you can't dget() without holding any locks! I believe you can - for the same reasons we can take a reference to an inode without holding the inode_lock. That is, as long as the caller already holds an active reference to the dentry, dget() can be used to take another reference without needing the dcache_lock. Such usage appears to be described in the comment above dget() and there's a BUG_ON() in dget() to catch callers that don't already have an active reference. An example of a valid unlocked dget(): d_alloc() does an unlocked dget() to take a reference to the parent dentry which we already are guaranteed to have a reference to. As to d_validate() - it depends on the caller behaviour as to whether the unlocked dget() is valid or not. From a cursory check of the NCP and SMB readdir caches, both appear to hold an active reference to the dentry it is passing to d_validate(). If that is the case then there is nothing wrong with the way d_validate uses dget(). Can someone with more SMB/NCP expertise than me validate the use of cached dentries? Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- 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
