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restic/internal/fuse/snapshots_dir.go
Michael Eischer 51173c5003 fuse: forget fs.Node instances on request by the kernel
Forget fs.Node instances once the kernel frees the corresponding nodeId.
This ensures that restic does not run out of memory on large snapshots.
2024-09-14 18:11:44 +02:00

176 lines
4.3 KiB
Go

//go:build darwin || freebsd || linux
// +build darwin freebsd linux
package fuse
import (
"context"
"os"
"syscall"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/restic"
"github.com/anacrolix/fuse"
"github.com/anacrolix/fuse/fs"
)
// SnapshotsDir is a actual fuse directory generated from SnapshotsDirStructure
// It uses the saved prefix to select the corresponding MetaDirData.
type SnapshotsDir struct {
root *Root
forget forgetFn
inode uint64
parentInode uint64
dirStruct *SnapshotsDirStructure
prefix string
cache treeCache
}
// ensure that *SnapshotsDir implements these interfaces
var _ = fs.HandleReadDirAller(&SnapshotsDir{})
var _ = fs.NodeForgetter(&SnapshotsDir{})
var _ = fs.NodeStringLookuper(&SnapshotsDir{})
// NewSnapshotsDir returns a new directory structure containing snapshots and "latest" links
func NewSnapshotsDir(root *Root, forget forgetFn, inode, parentInode uint64, dirStruct *SnapshotsDirStructure, prefix string) *SnapshotsDir {
debug.Log("create snapshots dir, inode %d", inode)
return &SnapshotsDir{
root: root,
forget: forget,
inode: inode,
parentInode: parentInode,
dirStruct: dirStruct,
prefix: prefix,
cache: *newTreeCache(),
}
}
// Attr returns the attributes for any dir in the snapshots directory structure
func (d *SnapshotsDir) Attr(_ context.Context, attr *fuse.Attr) error {
attr.Inode = d.inode
attr.Mode = os.ModeDir | 0555
attr.Uid = d.root.uid
attr.Gid = d.root.gid
debug.Log("attr: %v", attr)
return nil
}
// ReadDirAll returns all entries of the SnapshotsDir.
func (d *SnapshotsDir) ReadDirAll(ctx context.Context) ([]fuse.Dirent, error) {
debug.Log("ReadDirAll()")
// update snapshots
meta, err := d.dirStruct.UpdatePrefix(ctx, d.prefix)
if err != nil {
return nil, unwrapCtxCanceled(err)
} else if meta == nil {
return nil, syscall.ENOENT
}
items := []fuse.Dirent{
{
Inode: d.inode,
Name: ".",
Type: fuse.DT_Dir,
},
{
Inode: d.parentInode,
Name: "..",
Type: fuse.DT_Dir,
},
}
for name, entry := range meta.names {
if ctx.Err() != nil {
return nil, ctx.Err()
}
d := fuse.Dirent{
Inode: inodeFromName(d.inode, name),
Name: name,
Type: fuse.DT_Dir,
}
if entry.linkTarget != "" {
d.Type = fuse.DT_Link
}
items = append(items, d)
}
return items, nil
}
// Lookup returns a specific entry from the SnapshotsDir.
func (d *SnapshotsDir) Lookup(ctx context.Context, name string) (fs.Node, error) {
debug.Log("Lookup(%s)", name)
meta, err := d.dirStruct.UpdatePrefix(ctx, d.prefix)
if err != nil {
return nil, unwrapCtxCanceled(err)
} else if meta == nil {
return nil, syscall.ENOENT
}
return d.cache.lookupOrCreate(name, func(forget forgetFn) (fs.Node, error) {
entry := meta.names[name]
if entry == nil {
return nil, syscall.ENOENT
}
inode := inodeFromName(d.inode, name)
if entry.linkTarget != "" {
return newSnapshotLink(d.root, forget, inode, entry.linkTarget, entry.snapshot)
} else if entry.snapshot != nil {
return newDirFromSnapshot(d.root, forget, inode, entry.snapshot)
}
return NewSnapshotsDir(d.root, forget, inode, d.inode, d.dirStruct, d.prefix+"/"+name), nil
})
}
func (d *SnapshotsDir) Forget() {
d.forget()
}
// SnapshotLink
type snapshotLink struct {
root *Root
forget forgetFn
inode uint64
target string
snapshot *restic.Snapshot
}
var _ = fs.NodeForgetter(&snapshotLink{})
var _ = fs.NodeReadlinker(&snapshotLink{})
// newSnapshotLink
func newSnapshotLink(root *Root, forget forgetFn, inode uint64, target string, snapshot *restic.Snapshot) (*snapshotLink, error) {
return &snapshotLink{root: root, forget: forget, inode: inode, target: target, snapshot: snapshot}, nil
}
// Readlink
func (l *snapshotLink) Readlink(_ context.Context, _ *fuse.ReadlinkRequest) (string, error) {
return l.target, nil
}
// Attr
func (l *snapshotLink) Attr(_ context.Context, a *fuse.Attr) error {
a.Inode = l.inode
a.Mode = os.ModeSymlink | 0777
a.Size = uint64(len(l.target))
a.Blocks = (a.Size + blockSize - 1) / blockSize
a.Uid = l.root.uid
a.Gid = l.root.gid
a.Atime = l.snapshot.Time
a.Ctime = l.snapshot.Time
a.Mtime = l.snapshot.Time
a.Nlink = 1
return nil
}
func (l *snapshotLink) Forget() {
l.forget()
}