On Wed, Apr 06, 2011 at 09:44:28AM -0400, Christoph Hellwig wrote: > On Wed, Apr 06, 2011 at 09:21:35PM +1000, Dave Chinner wrote: > > Sure, but the question must be asked - why is ext3/4 even starting a > > transaction on a clean filesystem during sync? A frozen filesystem, > > by definition, is a clean filesytem, and therefore sync calls of any > > kind should not be trying to write to the FS or start transactions. > > XFS does this just fine, so I'd consider such behaviour on a frozen > > filesystem a bug in ext3/4... > > XFS does have one special case for this. When writing the dummy log > record at the end of the freeze process we use _xfs_alloc_trans to > bypass the frozen filesystem check as we have to write out this record > when the filesystem already is frozen. But that's after the main > sync with its normal transactions. Right, that is a special case in the _freeze process_ (i.e. before we've declared the FS frozen), not a normal operation on a frozen filesystem. If you want to list exceptions (i.e. where we explicitly avoid writes to frozen fs), look for xfs_fs_writeable(), which stops various write operations from proceeding when the fs is either frozen, read-only or shut down. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
