On Mon, Jul 20, 2009 at 05:36:20PM -0600, Andreas Dilger wrote: > On Jul 20, 2009 19:04 -0400, Valerie Aurora wrote: > > I think it's extremely accurate and detailed, but too long - people's > > brains turn off after about the 15th line or so. Here's an attempt to > > distill your description down and refer out to another document (which > > one?) for people who want to learn more. > > > > (Sorry for the whitespace damage.) > > > > -VAL > > > > config EXT3_DEFAULTS_TO_ORDERED > > bool "Default to 'data=ordered' in ext3" > > depends on EXT3_FS > > help > > > > If the mount options for an ext3 filesystem do not > > include a journal mode, mount it in "data=ordered" mode. > > I would make this a bit more clear: > > This option sets the default journal mode for ext3 filesystems > which do not explicitly specify it in /etc/fstab or at mount > time. It is always possible to set the journal mode for each > filesystem independently with "data=writeback", "data=ordered", > or "data=journal" mount options. > > > The journal mode options for ext3 have different tradeoffs > > between when data is guaranteed to be on disk and > > performance. Many applications assume "data=ordered" > > semantics and may lose, destroy, or reveal other user's data > > in other journal modes. However, "data=ordered" mode can > > also result in major performance problems, including long > > delays before an fsync() call returns. For details, see: > > I think the "... lose, destroy, ..." part is confusing, as it mentions > "data=ordered" first and it isn't until the end of the sentence that > it is clear that "lose, destroy, ..." does not apply to data=ordered. > Also "data=journal" also does not apply in this case, only "data=writeback" > so we may as well call that out explicitly. > > ... Many applications do not explicitly sync data and assume > "data=ordered" mode. Saying 'N' here will use "data=writeback" > as the default for all ext3 filesystems, and may result in > files with no data, or garbage data from deleted files, > which is a security risk on a multi-user system. However, ... Good points. I think Ted's rewrite addresses most of them, what do you think? -VAL -- 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
