On Sun, Apr 26, 2009 at 03:07:14AM -0400, Christoph Hellwig wrote: > On Sat, Apr 25, 2009 at 11:49:23PM -0400, Theodore Ts'o wrote: > > The function ext4_mark_recovery_complete() is called from two call > > paths: either (a) while mounting the filesystem, in which case there's > > no danger of any other CPU calling write_super() until the mount is > > completed, and (b) while remounting the filesystem read-write, in > > which case the fs core has already locked the superblock, and in any > > case write_super() wouldn't be called until the filesystem is > > successfully changed from being mounted read-only to read-write. > > Currently ext4_remount releases/reqacquires lock_super around > ext4_mark_recovery_complete, and unfortunately currently ->write_super > can be called on a r/o filesystem (that's why we have the MS_RDONLY > checks in all instance, I plan to clean that mess up). That's true, but the patch also takes out the release/reacquire in in ext4_remount (which was particularly ugly, belch). So even if write_super gets called on an r/o filesystem (why?!?), we should be safe because remount will hold lock_super() throughout the entire remount operation. We could delay this cleanup until you clean the mess with write_super, but I don't think it would be harmful in removing the lock_super()/unlock_super() pair in ext4_mark_recovery_complete(), and the unlock_super()/lock_super() pair in ext4_remount before then. Am I missing something? - Ted -- 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
