Hi Folks, These two patches change the XFS directory locking to shut up lockdep. Ever since we changed the locking to serialise readdir via the ILOCK for CXFS, lockdep has been producing false positive warnings because filldir can trigger page faults and lockdep can't be easily told that you can't take page faults on directory inodes so it warns about all sorts of stuff that just can't deadlock. To fix this, we need to change the directory locking (again!) to use a different structure that separates the page fault path out from underneath the ILOCK. TO do this, we have to treat the directory data the same way we treat file data: The IOLOCK serialises access to the data sections of the inode, the ILOCK serialises access to the metadata sections of the inode. This means that we need to take the IOLOCK in operations that modify the directory data, which means we need nested PARENT lockdep annotations because we need to lock two inodes at a time, so the inode subclass lockdep annotations need a complete rework to support this. This annotation rework is the first patch in the series. THe second patch in the series is the directory locking rework. It's all relatively straight forward - on modification the IOLOCK is taken EXCL before we start transactions, the transaction join is modified to understand the IOLOCK is also held, and the transaction commit releases the IOLOCK. On readdir, we hold the IOLOCK in SHARED mode across the readdir operation, and only hold the ILOCK when doing operations that walk the extent tree and map directory buffers. Oleg and Jan, this patchset should fix the lockdep issues that have been seen with the freeze rework. Oleg, can you you try it with your current patchset and testing and let me know if there are any issues that you see? Cheers, Dave. _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
