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// Copyright (C) 2022 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package rebuildnodes
import (
"context"
"errors"
iofs "io/fs"
"strings"
"github.com/datawire/dlib/dlog"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfstree"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfsprogs/btrfsinspect"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfsprogs/btrfsutil"
"git.lukeshu.com/btrfs-progs-ng/lib/diskio"
)
// lostAndFoundNodes returns the set of nodes don't have another node
// claiming it as a child.
func lostAndFoundNodes(ctx context.Context, fs _FS, nodeScanResults btrfsinspect.ScanDevicesResult) (map[btrfsvol.LogicalAddr]struct{}, error) {
dlog.Info(ctx, "Identifying lost+found nodes...")
lastPct := -1
total := countNodes(nodeScanResults)
progress := func(done int) {
pct := int(100 * float64(done) / float64(total))
if pct != lastPct || done == total {
dlog.Infof(ctx, "... %v%% (%v/%v)",
pct, done, total)
lastPct = pct
}
}
visitedNodes := make(map[btrfsvol.LogicalAddr]struct{})
btrfsutil.WalkAllTrees(ctx, fs, btrfsutil.WalkAllTreesHandler{
TreeWalkHandler: btrfstree.TreeWalkHandler{
// Don't use `PreNode` because we don't want to run this on bad nodes.
Node: func(path btrfstree.TreePath, _ *diskio.Ref[btrfsvol.LogicalAddr, btrfstree.Node]) error {
addr := path.Node(-1).ToNodeAddr
if _, alreadyVisited := visitedNodes[addr]; alreadyVisited {
// Can happen because of COW subvolumes;
// this is really a DAG not a tree.
return iofs.SkipDir
}
visitedNodes[addr] = struct{}{}
progress(len(visitedNodes))
return nil
},
},
Err: func(err *btrfsutil.WalkError) {
// do nothing
if !errors.Is(err, btrfstree.ErrNotANode) && !strings.Contains(err.Error(), "read: could not map logical address") {
dlog.Errorf(ctx, "dbg walk err: %v", err)
}
},
})
orphanedNodes := make(map[btrfsvol.LogicalAddr]int)
for _, devResults := range nodeScanResults {
for laddr := range devResults.FoundNodes {
if _, attached := visitedNodes[laddr]; !attached {
orphanedNodes[laddr] = 0
}
}
}
if len(visitedNodes)+len(orphanedNodes) != total {
panic("should not happen")
}
dlog.Infof(ctx,
"... (finished processing %v attached nodes, proceeding to process %v lost nodes, for a total of %v)",
len(visitedNodes), len(orphanedNodes), len(visitedNodes)+len(orphanedNodes))
// 'orphanedRoots' is a subset of 'orphanedNodes'; start with
// it as the complete orphanedNodes, and then remove entries.
orphanedRoots := make(map[btrfsvol.LogicalAddr]struct{}, len(orphanedNodes))
for node := range orphanedNodes {
orphanedRoots[node] = struct{}{}
}
for potentialRoot := range orphanedNodes {
if orphanedNodes[potentialRoot] > 1 {
continue
}
walkFromNode(ctx, fs, potentialRoot,
func(err *btrfstree.TreeError) {
// do nothing
},
btrfstree.TreeWalkHandler{
// Don't use `PreNode` because we don't want to run this on bad
// nodes (it'd screw up `len(visitedNodes)`).
Node: func(path btrfstree.TreePath, _ *diskio.Ref[btrfsvol.LogicalAddr, btrfstree.Node]) error {
addr := path.Node(-1).ToNodeAddr
if addr != potentialRoot {
delete(orphanedRoots, addr)
}
if _, alreadyVisited := visitedNodes[addr]; alreadyVisited {
return iofs.SkipDir
}
visitedNodes[addr] = struct{}{}
progress(len(visitedNodes))
return nil
},
},
)
}
if len(visitedNodes) != total {
panic("should not happen")
}
dlog.Infof(ctx, "... identified %d lost+found nodes", len(orphanedRoots))
return orphanedRoots, nil
}
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