1
0
Fork 0
mirror of https://github.com/restic/restic.git synced 2024-12-23 00:07:25 +00:00
restic/internal/fuse/inode.go
greatroar 189e0fe5a9 fuse: Better inode generation
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)
2022-11-16 08:35:01 +01:00

44 lines
1.2 KiB
Go

//go:build darwin || freebsd || linux
// +build darwin freebsd linux
package fuse
import (
"encoding/binary"
"github.com/cespare/xxhash/v2"
"github.com/restic/restic/internal/restic"
)
// inodeFromName generates an inode number for a file in a meta dir.
func inodeFromName(parent uint64, name string) uint64 {
inode := parent ^ xxhash.Sum64String(cleanupNodeName(name))
// Inode 0 is invalid and 1 is the root. Remap those.
if inode < 2 {
inode += 2
}
return inode
}
// inodeFromNode generates an inode number for a file within a snapshot.
func inodeFromNode(parent uint64, node *restic.Node) (inode uint64) {
if node.Links > 1 && node.Type != "dir" {
// If node has hard links, give them all the same inode,
// irrespective of the parent.
var buf [16]byte
binary.LittleEndian.PutUint64(buf[:8], node.DeviceID)
binary.LittleEndian.PutUint64(buf[8:], node.Inode)
inode = xxhash.Sum64(buf[:])
} else {
// Else, use the name and the parent inode.
// node.{DeviceID,Inode} may not even be reliable.
inode = parent ^ xxhash.Sum64String(cleanupNodeName(node.Name))
}
// Inode 0 is invalid and 1 is the root. Remap those.
if inode < 2 {
inode += 2
}
return inode
}