Dear: We are using btrfs in an embedded arm/linux device.
The bootloader (u-boot) has only limited support for btrfs. Occasionally the device lost power supply unexpectedly, leaving an inconsistent file system on eMMC. If I dump the partition image from eMMC and mount it on linux desktop, the file system is perfectly usable. My guess is that the linux kernel can fully handle the journalled update and garbage data. But the u-boot cannot. So I consider to add a minimal ext4 rootfs partition as a fallback. When u-boot cannot read file from btrfs partition, it can switch to a minimal Linux system booting from an ext4 fs. Then I have a chance to use some tool to fix btrfs volume and reboot the system. My question is which tools is recommended for this purpose? According to the following page: https://btrfs.wiki.kernel.org/index.php/Btrfsck btrfsck is said to be deprecated. `btrfs check --repair` seems to be a full volume check and time-consuming. All I need is just a good superblock and a few files could be loaded. Most frequently complaints from u-boot is the superblock issue such as `root_backup not found`. It there a way to just fix the superblock, settle all journalled update, and make sure the required several files is OK? Tianfu Ma
