On Thu, Jun 20, 2013 at 05:34:18PM -0400, Ryan Lortie wrote: > > in https://www.kernel.org/doc/Documentation/filesystems/ext4.txt > > which says to me "replace by rename is guaranteed safe in modern ext4, > under default mount options". It's not _guaranteed_ safe. It significantly reduces the chances of data loss in case of a crash, but it's possible for the transaction containing the rename to close before the blocks are written back. So if the transaction is almost full, or there is a fsync() racing with the rename(), such that the file system operation to allocate the delayed allocation blocks ends up in a different transaction than the transaction where the rename took place (race #1), and then you crash before the second transaction completes (race #2), you could lose data. You'll have to make your own decision about how likely this combination is to happen. The failure scenario would probably be something like the user who plays tux racer all the time, and uses crappy proprietary drivers that crash the system every single time an OpenGL application exits. If they think that's normal, and are willing to live with the crap proprietary drivers, and they are also the sort of people who carefully position all of their windows to be precisely just so, and if the !@#!?! desktop libraries are still bogusly rewriting the entire contents of every single registry file, regardless of whether the application changed anything --- then eventually, said user will whine about how the hours she spent obsessively setting up their window layout got lost after Tux Racer creashed their system *again*. (Unfortunately, this example is not entirely hypothetical....) Regards, - 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
