Since 0.15 (#4020), inodes are generated as hashes of names, xor'd with
the parent inode. That means that the inode of a/b/b is
h(a/b/b) = h(a) ^ h(b) ^ h(b) = h(a).
I.e., the grandchild has the same inode as the grandparent. GNU find
trips over this because it thinks it has encountered a loop in the
filesystem, and fails to search a/b/b. This happens more generally when
the same name occurs an even number of times.
Fix this by multiplying the parent by a large prime, so the combining
operation is not longer symmetric in its arguments. This is what the FNV
hash does, which we used prior to 0.15. The hash is now
h(a/b/b) = h(b) ^ p*(h(b) ^ p*h(a))
Note that we already ensure that h(x) is never zero.
Collisions can still occur, but they should be much less likely to occur
within a single path.
Fixes#4253.
TestRepository and its variants always returned no-op cleanup functions.
If they ever do need to do cleanup, using testing.T.Cleanup is easier
than passing these functions around.
Hard links to the same file now get the same inode within the FUSE
mount. Also, inode generation is faster and, more importantly, no longer
allocates.
Benchmarked on Linux/amd64. Old means the benchmark with
sink = fs.GenerateDynamicInode(1, sub.node.Name)
instead of calling inodeFromNode. Results:
name old time/op new time/op delta
Inode/no_hard_links-8 137ns ± 4% 34ns ± 1% -75.20% (p=0.000 n=10+10)
Inode/hard_link-8 33.6ns ± 1% 9.5ns ± 0% -71.82% (p=0.000 n=9+8)
name old alloc/op new alloc/op delta
Inode/no_hard_links-8 48.0B ± 0% 0.0B -100.00% (p=0.000 n=10+10)
Inode/hard_link-8 0.00B 0.00B ~ (all equal)
name old allocs/op new allocs/op delta
Inode/no_hard_links-8 1.00 ± 0% 0.00 -100.00% (p=0.000 n=10+10)
Inode/hard_link-8 0.00 0.00 ~ (all equal)
In #2584 this was changed to use the uid/gid of the root node. This
would be okay for the top-level directory of a snapshot, however, this
change also applied to normal directories within a snapshot. This
change reverts the problematic part and adds a test that directory
attributes are represented correctly.
- Add Open() functionality to dir
- only access index for blobs when file is read
- Implement NodeOpener and put one-time file stuff there
- Add comment about locking as suggested by bazil.org/fuse
=> Thanks at Michael Eischer for suggesting the last two improvements
This command can only be built on Darwin, FreeBSD and Linux
(and if we upgrade bazil.org/fuse, only FreeBSD and Linux:
https://github.com/bazil/fuse/issues/224).
Listing the few supported operating systems explicitly here makes
porting restic to new platforms easier.
Michael Eischer