From b9c96ea703dcc84fcd8e3c051617c25579c4e4e1 Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@lukeshu.com>
Date: Sat, 8 Oct 2022 16:25:54 -0600
Subject: mount: Allow ignoring file checksum errors

---
 lib/btrfs/io4_fs.go                  | 40 +++++++++++++++++++-----------------
 lib/btrfsprogs/btrfsinspect/mount.go | 12 ++++++-----
 2 files changed, 28 insertions(+), 24 deletions(-)

(limited to 'lib')

diff --git a/lib/btrfs/io4_fs.go b/lib/btrfs/io4_fs.go
index 9391820..ea81bc2 100644
--- a/lib/btrfs/io4_fs.go
+++ b/lib/btrfs/io4_fs.go
@@ -66,7 +66,8 @@ type Subvolume struct {
 		Superblock() (*btrfstree.Superblock, error)
 		ReadAt(p []byte, off btrfsvol.LogicalAddr) (int, error)
 	}
-	TreeID btrfsprim.ObjID
+	TreeID      btrfsprim.ObjID
+	NoChecksums bool
 
 	rootOnce sync.Once
 	rootVal  btrfsitem.Root
@@ -414,26 +415,27 @@ func (file *File) maybeShortReadAt(dat []byte, off int64) (int, error) {
 			if err != nil {
 				return 0, err
 			}
+			if !file.SV.NoChecksums {
+				sumRun, err := LookupCSum(file.SV.FS, sb.ChecksumType, blockBeg)
+				if err != nil {
+					return 0, fmt.Errorf("checksum@%v: %w", blockBeg, err)
+				}
+				_expSum, ok := sumRun.SumForAddr(blockBeg)
+				if !ok {
+					panic(fmt.Errorf("run from LookupCSum(fs, typ, %v) did not contain %v: %#v",
+						blockBeg, blockBeg, sumRun))
+				}
+				expSum := _expSum.ToFullSum()
 
-			sumRun, err := LookupCSum(file.SV.FS, sb.ChecksumType, blockBeg)
-			if err != nil {
-				return 0, fmt.Errorf("checksum@%v: %w", blockBeg, err)
-			}
-			_expSum, ok := sumRun.SumForAddr(blockBeg)
-			if !ok {
-				panic(fmt.Errorf("run from LookupCSum(fs, typ, %v) did not contain %v: %#v",
-					blockBeg, blockBeg, sumRun))
-			}
-			expSum := _expSum.ToFullSum()
-
-			actSum, err := sb.ChecksumType.Sum(block[:])
-			if err != nil {
-				return 0, fmt.Errorf("checksum@%v: %w", blockBeg, err)
-			}
+				actSum, err := sb.ChecksumType.Sum(block[:])
+				if err != nil {
+					return 0, fmt.Errorf("checksum@%v: %w", blockBeg, err)
+				}
 
-			if actSum != expSum {
-				return 0, fmt.Errorf("checksum@%v: actual sum %v != expected sum %v",
-					blockBeg, actSum, expSum)
+				if actSum != expSum {
+					return 0, fmt.Errorf("checksum@%v: actual sum %v != expected sum %v",
+						blockBeg, actSum, expSum)
+				}
 			}
 			return n, nil
 		}
diff --git a/lib/btrfsprogs/btrfsinspect/mount.go b/lib/btrfsprogs/btrfsinspect/mount.go
index 6cf6317..2a0b232 100644
--- a/lib/btrfsprogs/btrfsinspect/mount.go
+++ b/lib/btrfsprogs/btrfsinspect/mount.go
@@ -30,7 +30,7 @@ import (
 	"git.lukeshu.com/btrfs-progs-ng/lib/slices"
 )
 
-func MountRO(ctx context.Context, fs *btrfs.FS, mountpoint string) error {
+func MountRO(ctx context.Context, fs *btrfs.FS, mountpoint string, noChecksums bool) error {
 	pvs := fs.LV.PhysicalVolumes()
 	if len(pvs) < 1 {
 		return errors.New("no devices")
@@ -43,8 +43,9 @@ func MountRO(ctx context.Context, fs *btrfs.FS, mountpoint string) error {
 
 	rootSubvol := &subvolume{
 		Subvolume: btrfs.Subvolume{
-			FS:     btrfsutil.NewBrokenTrees(ctx, fs),
-			TreeID: btrfsprim.FS_TREE_OBJECTID,
+			FS:          btrfsutil.NewBrokenTrees(ctx, fs),
+			TreeID:      btrfsprim.FS_TREE_OBJECTID,
+			NoChecksums: noChecksums,
 		},
 		DeviceName: deviceName,
 		Mountpoint: mountpoint,
@@ -185,8 +186,9 @@ func (sv *subvolume) LoadDir(inode btrfsprim.ObjID) (val *btrfs.Dir, err error)
 					sv.grp.Go(workerName, func(ctx context.Context) error {
 						subSv := &subvolume{
 							Subvolume: btrfs.Subvolume{
-								FS:     sv.FS,
-								TreeID: entry.Location.ObjectID,
+								FS:          sv.FS,
+								TreeID:      entry.Location.ObjectID,
+								NoChecksums: sv.NoChecksums,
 							},
 							DeviceName: sv.DeviceName,
 							Mountpoint: filepath.Join(sv.Mountpoint, subMountpoint[1:]),
-- 
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