Hi all, Online repair fixes metadata structures by writing a new copy out to disk and atomically committing the new structure into the filesystem. For this to work, we need to reserve all the space we're going to need ahead of time so that the atomic commit transaction is as small as possible. We also require the reserved space to be freed if the system goes down, or if we decide not to commit the repair, or if we reserve too much space. To keep the atomic commit transaction as small as possible, we would like to allocate some space and simultaneously schedule automatic reaping of the reserved space, even on log recovery. EFIs are the mechanism to get us there, but we need to use them in a novel manner. Once we allocate the space, we want to hold on to the EFI (relogging as necessary) until we can commit or cancel the repair. EFIs for written committed blocks need to go away, but unwritten or uncommitted blocks can be freed like normal. Earlier versions of this patchset directly manipulated the log items, but Dave thought that to be a layering violation. For v27, I've modified the defer ops handling code to be capable of pausing a deferred work item. Log intent items are created as they always have been, but paused items are pushed onto a side list when finishing deferred work items, and pushed back onto the transaction after that. Log intent done item are not created for paused work. The second part adds a "stale" flag to the EFI so that the repair reservation code can dispose of an EFI the normal way, but without the space actually being freed. If you're going to start using this code, I strongly recommend pulling from my git trees, which are linked below. This has been running on the djcloud for months with no problems. 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-auto-reap-space-reservations xfsprogs git tree: https://git.kernel.org/cgit/linux/kernel/git/djwong/xfsprogs-dev.git/log/?h=repair-auto-reap-space-reservations --- fs/xfs/Makefile | 1 fs/xfs/libxfs/xfs_ag.c | 2 fs/xfs/libxfs/xfs_alloc.c | 104 +++++++ fs/xfs/libxfs/xfs_alloc.h | 22 +- fs/xfs/libxfs/xfs_bmap.c | 4 fs/xfs/libxfs/xfs_bmap_btree.c | 2 fs/xfs/libxfs/xfs_btree_staging.h | 7 fs/xfs/libxfs/xfs_defer.c | 229 ++++++++++++++-- fs/xfs/libxfs/xfs_defer.h | 20 + fs/xfs/libxfs/xfs_ialloc.c | 5 fs/xfs/libxfs/xfs_ialloc_btree.c | 2 fs/xfs/libxfs/xfs_refcount.c | 6 fs/xfs/libxfs/xfs_refcount_btree.c | 2 fs/xfs/scrub/agheader_repair.c | 1 fs/xfs/scrub/common.c | 1 fs/xfs/scrub/newbt.c | 510 ++++++++++++++++++++++++++++++++++++ fs/xfs/scrub/newbt.h | 65 +++++ fs/xfs/scrub/reap.c | 7 fs/xfs/scrub/scrub.c | 2 fs/xfs/scrub/trace.h | 37 +++ fs/xfs/xfs_extfree_item.c | 12 - fs/xfs/xfs_reflink.c | 2 fs/xfs/xfs_trace.h | 13 + 23 files changed, 990 insertions(+), 66 deletions(-) create mode 100644 fs/xfs/scrub/newbt.c create mode 100644 fs/xfs/scrub/newbt.h
