>> The test below creates a sparse file and then fills a hole with >> O_DIRECT. As far as I can tell from reading generic_osync_inode, the >> filesystem metadata is only forced to disk if i_size changes during the >> file write. I've tested ext3, xfs and reiserfs and they all skip the >> commit when filling holes. >> >> I would argue that filling holes via O_DIRECT is supposed to commit the >> metadata required to find those file blocks later. At least on ext3, >> O_SYNC does force a commit on fill holes (haven't tested others). >> >I don't think it's a bug. Sure, O_DIRECT is synchronous, but that's >because it is, err, direct. Not because it provides extra data-integrity >guarantees. If you want those guarantees, use O_SYNC as well. That makes sense, but how do you explain the committing of the size change without O_SYNC? That seems wrong to me. This does need to be documented carefully, because a person could easily believe, even subconsciously, that O_DIRECT makes the entire file write direct, and sloppy documentation might actually use words to that effect. -- Bryan Henderson IBM Almaden Research Center San Jose CA Filesystems - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
