It seems that you are really hung up on whether or not the filesystem metadata is consistent after a power failure, when I'd argue that the problem with using storage devices that don't have good powerfail properties have much bigger problems (such as the potential for silent data corruption, or even if fsck will fix a trashed inode table with ext2, massive data loss). So instead of your suggested patch, it might be better simply to have a file in Documentation/filesystems that states something along the lines of: "There are storage devices that high highly undesirable properties when they are disconnected or suffer power failures while writes are in progress; such devices include flash devices and software RAID 5/6 arrays without journals, as well as hardware RAID 5/6 devices without battery backups. These devices have the property of potentially corrupting blocks being written at the time of the power failure, and worse yet, amplifying the region where blocks are corrupted such that adjacent sectors are also damaged during the power failure. Users who use such storage devices are well advised take countermeasures, such as the use of Uninterruptible Power Supplies, and making sure the flash device is not hot-unplugged while the device is being used. Regular backups when using these devices is also a Very Good Idea. Otherwise, file systems placed on these devices can suffer silent data and file system corruption. An forced use of fsck may detect metadata corruption resulting in file system corruption, but will not suffice to detect data corruption." My big complaint is that you seem to think that ext3 some how let you down, but I'd argue that the real issue is that the storage device let you down. Any journaling filesystem will have the properties that you seem to be complaining about, so the fact that your patch only documents this as assumptions made by ext2 and ext3 is unfair; it also applies to xfs, jfs, reiserfs, reiser4, etc. Further more, most users are even more concerned about possibility of massive data loss and/or silent data corruption. So if your complaint that we don't have documentation warning users about the potential pitfalls of using storage devices with undesirable power fail properties, let's document that as a shortcoming in those storage devices. - 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
