mount: fix weed inode nlookup do not equel kernel inode nlookup (#7682)

* mount: fix weed inode nlookup do not equel kernel inode nlookup

* mount: add underflow protection for nlookup decrement in Forget

* mount: use consistent == 0 check for uint64 nlookup

* Update weed/mount/inode_to_path.go

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

* mount: snapshot data before unlock in Forget to avoid using deleted InodeEntry

---------

Co-authored-by: chrislu <chris.lu@gmail.com>
Co-authored-by: Chris Lu <chrislusf@users.noreply.github.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

weed/mount/inode_to_path.go

@@ -1,11 +1,12 @@
 package mount
 
 import (
+	"sync"
+	"time"
+
 	"github.com/hanwen/go-fuse/v2/fuse"
 	"github.com/seaweedfs/seaweedfs/weed/glog"
 	"github.com/seaweedfs/seaweedfs/weed/util"
-	"sync"
-	"time"
 )
 
 type InodeToPath struct {
@@ -41,7 +42,6 @@ func (ie *InodeEntry) removeOnePath(p util.FullPath) bool {
 		ie.paths[x] = ie.paths[x+1]
 	}
 	ie.paths = ie.paths[0 : len(ie.paths)-1]
-	ie.nlookup--
 	return true
 }
 
@@ -230,9 +230,6 @@ func (i *InodeToPath) removePathFromInode2Path(inode uint64, path util.FullPath)
 	if !ie.removeOnePath(path) {
 		return
 	}
-	if len(ie.paths) == 0 {
-		delete(i.inode2path, inode)
-	}
 }
 
 func (i *InodeToPath) MovePath(sourcePath, targetPath util.FullPath) (sourceInode, targetInode uint64) {
@@ -259,9 +256,6 @@ func (i *InodeToPath) MovePath(sourcePath, targetPath util.FullPath) (sourceInod
 			}
 		}
 		entry.isChildrenCached = false
-		if !targetFound {
-			entry.nlookup++
-		}
 	} else {
 		glog.Errorf("MovePath %s to %s: sourceInode %d not found", sourcePath, targetPath, sourceInode)
 	}
@@ -269,24 +263,39 @@ func (i *InodeToPath) MovePath(sourcePath, targetPath util.FullPath) (sourceInod
 }
 
 func (i *InodeToPath) Forget(inode, nlookup uint64, onForgetDir func(dir util.FullPath)) {
+	var dirPaths []util.FullPath
+	callOnForgetDir := false
+
 	i.Lock()
 	path, found := i.inode2path[inode]
 	if found {
-		path.nlookup -= nlookup
-		if path.nlookup <= 0 {
+		if nlookup > path.nlookup {
+			glog.Errorf("kernel forget over-decrement: inode %d paths %v current %d forget %d", inode, path.paths, path.nlookup, nlookup)
+			path.nlookup = 0
+		} else {
+			path.nlookup -= nlookup
+		}
+		glog.V(4).Infof("kernel forget: inode %d paths %v nlookup %d", inode, path.paths, path.nlookup)
+		if path.nlookup == 0 {
+			if path.isDirectory && onForgetDir != nil {
+				dirPaths = append([]util.FullPath(nil), path.paths...)
+				callOnForgetDir = true
+			}
 			for _, p := range path.paths {
 				delete(i.path2inode, p)
 			}
 			delete(i.inode2path, inode)
+		} else {
+			glog.V(4).Infof("kernel forget but nlookup not zero: inode %d paths %v nlookup %d", inode, path.paths, path.nlookup)
 		}
+	} else {
+		glog.Warningf("kernel forget but inode not found: inode %d", inode)
 	}
 	i.Unlock()
-	if found {
-		if path.isDirectory && path.nlookup <= 0 && onForgetDir != nil {
-			path.isChildrenCached = false
-			for _, p := range path.paths {
-				onForgetDir(p)
-			}
+
+	if callOnForgetDir {
+		for _, p := range dirPaths {
+			onForgetDir(p)
 		}
 	}
 }

weed/mount/weedfs_dir_read.go

@@ -169,7 +169,7 @@ func (wfs *WFS) doReadDirectory(input *fuse.ReadIn, out *fuse.DirEntryList, isPl
 	processEachEntryFn := func(entry *filer.Entry) bool {
 		dirEntry.Name = entry.Name()
 		dirEntry.Mode = toSyscallMode(entry.Mode)
-		inode := wfs.inodeToPath.Lookup(dirPath.Child(dirEntry.Name), entry.Crtime.Unix(), entry.IsDirectory(), len(entry.HardLinkId) > 0, entry.Inode, isPlusMode)
+		inode := wfs.inodeToPath.Lookup(dirPath.Child(dirEntry.Name), entry.Crtime.Unix(), entry.IsDirectory(), len(entry.HardLinkId) > 0, entry.Inode, false)
 		dirEntry.Ino = inode
 		if !isPlusMode {
 			if !out.AddDirEntry(dirEntry) {
@@ -187,6 +187,7 @@ func (wfs *WFS) doReadDirectory(input *fuse.ReadIn, out *fuse.DirEntryList, isPl
 				entry = filer.FromPbEntry(string(dirPath), fh.GetEntry().GetEntry())
 			}
 			wfs.outputFilerEntry(entryOut, inode, entry)
+			wfs.inodeToPath.Lookup(dirPath.Child(dirEntry.Name), entry.Crtime.Unix(), entry.IsDirectory(), len(entry.HardLinkId) > 0, entry.Inode, true)
 		}
 		return true
 	}