On Mon, Jun 14, 2010 at 11:20:11AM -0400, Christoph Hellwig wrote: > On Thu, Jun 10, 2010 at 05:19:51PM +1000, Dave Chinner wrote: > > The emergency thaw process uses iterate_super() which holds the > > sb->s_umount lock in read mode. The current thaw_super() code takes > > the sb->s_umount lock in write mode, hence leading to an instant > > deadlock. > > > > Pass the emergency state into the thaw_bdev/thaw_super code to avoid > > taking the s_umount lock in this case. We are running under the bdev > > freeze mutex, so this is still serialised against freeze despite > > only having a read lock on the sb->s_umount. Hence it should be safe > > to execute in this manner, especially given that emergency thaw is a > > rarely executed "get-out-of-jail" feature. > > This is correct as long as no one calls thaw_super directly, which > is not the case currently. Yeah, the idea of the first two patches is that they can be applied to a current tree and backported and prevent the infinite loop or deadlock. The problem of thaw_bdev/thaw_super is what the rest of the patches are supposed to address. 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
