Hi all, This is the second revision of a patchset that adds to XFS userland tools support for online metadata scrubbing and repair. There aren't any on-disk format changes. Online scrub/repair support consists of four major pieces -- first, an ioctl that maps physical extents to their owners; second, various in-kernel metadata scrubbing ioctls to examine metadata records and cross-reference them with other filesystem metadata; third, an in-kernel mechanism for rebuilding damaged metadata objects and btrees; and fourth, a userspace component to initiate kernel scrubbing, walk all inodes and the directory tree, scrub data extents, and ask the kernel to repair anything that is broken. This new utility, xfs_scrub, is separate from the existing offline xfs_repair tool. Scrub has three main modes of operation -- in its most powerful mode, it iterates all XFS metadata and asks the kernel to check the metadata and repair it if necessary. The second most powerful mode can use certain VFS methods and XFS ioctls (BULKSTAT, GETBMAP, and GETFSMAP) to check as much metadata as it reasonably can from userspace. It cannot repair anything. The least powerful mode uses only VFS functions to access as much of the directory/file/xattr graph as possible. It has no mechanism to check internal metadata and also cannot repair anything. This is good enough for scrubbing non-XFS filesystems, but it is intended for the first mode to be used. Most of the patches in this series are direct imports of the libxfs changes that the kernel scrubber needed to operate. The changes to userspace programs are limited to wiring up ioctl support in xfs_io, support for per-field fuzzing in xfs_db, and the last patch, which creates the xfs_scrub program. The final patch in the series provides the xfs_scrub utility. If you're going to start using this mess, you probably ought to just pull from my github trees for kernel[1], xfsprogs[2], and xfstests[3]. The kernel patches in the git trees should apply to 4.9-rc3; xfsprogs patches to for-next; and xfstest to master. The patches have survived all auto group xfstests both with scrub-only mode and also a special debugging mode to xfs_scrub that forces it to rebuild the metadata structures even if they're not damaged. Note that I haven't thoroughly run the new tests in [3] that try to fuzz every field in every data structure on disk. This is an extraordinary way to eat your data. Enjoy! Comments and questions are, as always, welcome. --D [1] https://github.com/djwong/linux/tree/djwong-devel [2] https://github.com/djwong/xfsprogs/tree/djwong-devel [3] https://github.com/djwong/xfstests/tree/djwong-devel -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
