Hi all, I started looking through all the places where XFS has to deal with the rc_refcount attribute of refcount records, and noticed that offline repair doesn't handle the situation where there are more than 2^32 reverse mappings in an AG, or that there are more than 2^32 owners of a particular piece of AG space. I've estimated that it would take several months to produce a filesystem with this many records, but we really ought to do better at handling them than crashing or (worse) not crashing and writing out corrupt btrees due to integer truncation. Once I started using the bmap_inflate debugger command to create extreme reflink scenarios, I noticed that the memory usage of xfs_repair was astronomical. This I observed to be due to the fact that it allocates a single huge block mapping array for all files on the system, even though it only uses that array for data and attr forks that map metadata blocks (e.g. directories, xattrs, symlinks) and does not use it for regular data files. So I got rid of the 2^31-1 limits on the block map array and turned off the block mapping for regular data files. This doesn't answer the question of what to do if there are a lot of extents, but it kicks the can down the road until someone creates a maximally sized xattr tree, which so far nobody's ever stuck to long enough to complain about. 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 xfsprogs git tree: https://git.kernel.org/cgit/linux/kernel/git/djwong/xfsprogs-dev.git/log/?h=repair-support-4bn-records --- db/Makefile | 4 db/bmap_inflate.c | 564 +++++++++++++++++++++++++++++++++++++++++++++++++++++ db/command.c | 1 db/command.h | 1 man/man8/xfs_db.8 | 23 ++ repair/bmap.c | 26 +- repair/bmap.h | 9 - repair/dinode.c | 12 + repair/dir2.c | 2 repair/incore.c | 9 + repair/rmap.c | 26 +- repair/rmap.h | 4 repair/slab.c | 36 ++- repair/slab.h | 36 ++- 14 files changed, 680 insertions(+), 73 deletions(-) create mode 100644 db/bmap_inflate.c
