hi Ted, Thanks for the quick reply. On Thu, Jun 20, 2013, at 20:59, Theodore Ts'o wrote: > 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. I think you need to update the documentation. Specifically, this: "avoids the "zero-length" problem that can happen when a system crashes before the delayed allocation blocks are forced to disk" makes it sound like the replace-by-rename-without-fsync problem has been solved. This is the statement that caused me to remove the extra fsync() we had in GLib. Probably "avoids" should be replaced with "significantly reduces the chances of", as you write in your mail here. Note that "significantly reduces the chances of" is not good enough to prevent about a dozen reports of lost data that I alone have heard about in the past few days... https://bugzilla.gnome.org/show_bug.cgi?id=701560#c30 https://plus.google.com/113426423446646532879/posts/Mqepf8STJEK?cfem=1 https://bugzilla.redhat.com/show_bug.cgi?id=975521 https://bugzilla.gnome.org/show_bug.cgi?id=702574 https://bugzilla.gnome.org/show_bug.cgi?id=702394 and many "me too" cases from IRC, including reports from two Debian users. So I think that the "significantly reduces the chances of" statement itself is even suspect... It would be great if the docs would just said "If you want safety with ext4, it's going to be slow. Please always call fsync()." instead of making it sound like I'll probably be mostly OKish if I don't. > 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*. Dude.... Thanks again. -- 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
