On Wed, 9 Jul 2008 21:49:58 +1000 Dave Chinner <david@xxxxxxxxxxxxx> wrote: > > (e) none of the above. The kernel compilation will appear to pause > until the filesystem is unfrozen. No other visible effect should > occur. It will get blocked in a write or filesystem transaction > because the fs is frozen. > > Look at vfs_check_frozen() - any call to that will block if the > filesystem is frozen or being frozen. The generic hook is in > __generic_file_aio_write_nolock() and various other filesystems have > calls in their specific write paths (fuse, ntfs, ocfs2, xfs, xip) to > do this. yeah and mmap doesn't happen > > For all other modifications, filesystem specific methods of > blocking transactions are used. XFS uses vfs_check_frozen() in > xfs_trans_alloc(), ext3 (and probably ocfs2) do it via > their ->write_super_lockfs method calling journal_lock_updates(), > ext4 via jbd2_lock_updates() and so on.... and what if it's the process that you need to unfreeze the fs later? Good luck. -- If you want to reach me at my work email, use arjan@xxxxxxxxxxxxxxx For development, discussion and tips for power savings, visit http://www.lesswatts.org -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
