On 26-06-2007 04:16, David Chinner wrote: > On Mon, Jun 25, 2007 at 11:01:11PM +0200, Ingo Molnar wrote: >> * Satyam Sharma <[EMAIL PROTECTED]> wrote: >> >>> [ Ok, so we know that XFS wants to lock inodes in ascending inode >>> number order and not strictly the parent-first-child-second order that >>> rest of the fs/ code does, so that makes it difficult to teach lockdep >>> about this kind of lock ordering ... ] > > It does both - parent-first/child-second and ascending inode # order, > which is where the problem is. standing alone, these seem fine, but > they don't appear to work when the child has a lower inode number > than the parent. ...
>From xfs_inode.h: /* * Flags for lockdep annotations. * * XFS_I[O]LOCK_PARENT - for operations that require locking two inodes * (ie directory operations that require locking a directory inode and * an entry inode). The first inode gets locked with this flag so it * gets a lockdep subclass of 1 and the second lock will have a lockdep * subclass of 0. * * XFS_I[O]LOCK_INUMORDER - for locking several inodes at the some time * with xfs_lock_inodes(). This flag is used as the starting subclass * and each subsequent lock acquired will increment the subclass by one. * So the first lock acquired will have a lockdep subclass of 2, the * second lock will have a lockdep subclass of 3, and so on. */ I don't know xfs code, and probably miss something, but it seems there could be some inconsistency: lockdep warning shows mr_lock/1 taken both before and after mr_lock (i.e. /0). According to the above comment there should be always 1 before 0... Cheers, Jarek P. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
