Hi all, This is the first part of the nineteenth revision of a patchset that adds to XFS kernel support for online metadata scrubbing and repair. There aren't any on-disk format changes. New for this version is a rebase against 5.3-rc2, integration with the health reporting subsystem, and the explicit revalidation of all metadata structures that were rebuilt. Patch 1 lays the groundwork for scrub types specifying a revalidation function that will check everything that the repair function might have rebuilt. This will be necessary for the free space and inode btree repair functions, which rebuild both btrees at once. Patch 2 ensures that the health reporting query code doesn't get in the way of post-repair revalidation of all rebuilt metadata structures. Patch 3 creates a new data structure that provides an abstraction of a big memory array by using linked lists. This is where we store records for btree reconstruction. This first implementation is memory inefficient and consumes a /lot/ of kernel memory, but lays the groundwork for the last patch in the set to convert the implementation to use a (memfd) swap file, which enables us to use pageable memory without pounding the slab cache. Patches 4-10 implement reconstruction of the free space btrees, inode btrees, reference count btrees, inode records, inode forks, inode block maps, and symbolic links. Patch 11 implements a new data structure for storing arbitrary key/value pairs, which we're going to need to reconstruct extended attribute forks. Patches 12-14 clean up the block unmapping code so that we will be able to perform a mass reset of an inode's fork. This is a key component for salvaging extended attributes, freeing all the attr fork blocks, and reconstructing the extended attribute data. Patch 15 implements extended attribute salvage operations. There is no redundant or secondary xattr metadata, so the best we can do is trawl through the attr leaves looking for intact entities. Patch 16 augments scrub to rebuild extended attributes when any of the attr blocks are fragmented. Patch 17 implements reconstruction of quota blocks. Patch 18 converts both in-memory array implementations from the clunky linked list implementation to something resembling C arrays. The array data are backed by a (memfd) file, which means that idle data can be paged out to disk instead of pinning kernel memory. If you're going to start using this mess, you probably ought to just pull from my git trees, which are linked below. This is an extraordinary way to destroy everything. Enjoy! Comments and questions are, as always, welcome. --D kernel git tree: https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=repair-part-one xfsprogs git tree: https://git.kernel.org/cgit/linux/kernel/git/djwong/xfsprogs-dev.git/log/?h=repair-part-one fstests git tree: https://git.kernel.org/cgit/linux/kernel/git/djwong/xfstests-dev.git/log/?h=repair-part-one
