dll: FspFileSystemOpEnter, FspFileSystemOpLeave

inc/winfsp/winfsp.h

@@ -577,6 +577,11 @@ typedef struct _FSP_FILE_SYSTEM_INTERFACE
         PWSTR Pattern,
         PULONG PBytesTransferred);
 } FSP_FILE_SYSTEM_INTERFACE;
+typedef enum
+{
+    FSP_FILE_SYSTEM_OPERATION_GUARD_STRATEGY_FINE = 0,
+    FSP_FILE_SYSTEM_OPERATION_GUARD_STRATEGY_COARSE,
+} FSP_FILE_SYSTEM_OPERATION_GUARD_STRATEGY;
 typedef struct _FSP_FILE_SYSTEM
 {
     UINT16 Version;
@@ -592,6 +597,8 @@ typedef struct _FSP_FILE_SYSTEM
     PWSTR MountPoint;
     LIST_ENTRY MountEntry;
     UINT32 DebugLog;
+    FSP_FILE_SYSTEM_OPERATION_GUARD_STRATEGY OpGuardStrategy;
+    SRWLOCK OpGuardLock;
 } FSP_FILE_SYSTEM;
 /**
  * Create a file system object.
@@ -716,6 +723,12 @@ VOID FspFileSystemSetOperationGuard(FSP_FILE_SYSTEM *FileSystem,
     FileSystem->LeaveOperation = LeaveOperation;
 }
 static inline
+VOID FspFileSystemSetOperationGuardStrategy(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FILE_SYSTEM_OPERATION_GUARD_STRATEGY GuardStrategy)
+{
+    FileSystem->OpGuardStrategy = GuardStrategy;
+}
+static inline
 VOID FspFileSystemSetOperation(FSP_FILE_SYSTEM *FileSystem,
     ULONG Index,
     FSP_FILE_SYSTEM_OPERATION *Operation)
@@ -748,6 +761,10 @@ VOID FspFileSystemSetDebugLog(FSP_FILE_SYSTEM *FileSystem,
 /*
  * Operations
  */
+FSP_API VOID FspFileSystemOpEnter(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, FSP_FSCTL_TRANSACT_RSP *Response);
+FSP_API VOID FspFileSystemOpLeave(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, FSP_FSCTL_TRANSACT_RSP *Response);
 FSP_API NTSTATUS FspFileSystemOpCreate(FSP_FILE_SYSTEM *FileSystem,
     FSP_FSCTL_TRANSACT_REQ *Request, FSP_FSCTL_TRANSACT_RSP *Response);
 FSP_API NTSTATUS FspFileSystemOpOverwrite(FSP_FILE_SYSTEM *FileSystem,

src/dll/fs.c

@@ -125,6 +125,11 @@ FSP_API NTSTATUS FspFileSystemCreate(PWSTR DevicePath,
     FileSystem->Operations[FspFsctlTransactSetSecurityKind] = FspFileSystemOpSetSecurity;
     FileSystem->Interface = Interface;
 
+    FileSystem->OpGuardStrategy = FSP_FILE_SYSTEM_OPERATION_GUARD_STRATEGY_FINE;
+    InitializeSRWLock(&FileSystem->OpGuardLock);
+    FileSystem->EnterOperation = FspFileSystemOpEnter;
+    FileSystem->LeaveOperation = FspFileSystemOpLeave;
+
     *PFileSystem = FileSystem;
 
     return STATUS_SUCCESS;

src/dll/fsop.c

@@ -17,6 +17,92 @@
 
 #include <dll/library.h>
 
+/*
+ * The FspFileSystemOpEnter/FspFileSystemOpLeave functions guard against
+ * concurrent accesses. Two concurrency models are provided:
+ *
+ * 1. A fine-grained concurrency model where file system NAMESPACE accesses
+ * are guarded using an exclusive-shared (read-write) lock. File I/O is not
+ * guarded and concurrent reads/writes/etc. are possible. [Note that the FSD
+ * will still apply an exclusive-shared lock PER INDIVIDUAL FILE, but it will
+ * not limit I/O operations for different files.]
+ *
+ * The fine-grained concurrency model applies the exclusive-shared lock as
+ * follows:
+ *     - EXCL: SetVolumeLabel, Create, Cleanup(Delete), SetInformation(Rename)
+ *     - SHRD: GetVolumeInfo, Open, SetInformation(Disposition), ReadDirectory
+ *     - NONE: all other operations
+ *
+ * 2. A coarse-grained concurrency model where all file system accesses are
+ * guarded by a mutually exclusive lock.
+ */
+
+FSP_API VOID FspFileSystemOpEnter(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, FSP_FSCTL_TRANSACT_RSP *Response)
+{
+    switch (FileSystem->OpGuardStrategy)
+    {
+    case FSP_FILE_SYSTEM_OPERATION_GUARD_STRATEGY_FINE:
+        if ((FspFsctlTransactCreateKind == Request->Kind &&
+                FILE_OPEN != ((Request->Req.Create.CreateOptions >> 24) & 0xff)) ||
+            (FspFsctlTransactCleanupKind == Request->Kind &&
+                Request->Req.Cleanup.Delete) ||
+            (FspFsctlTransactSetInformationKind == Request->Kind &&
+                10/*FileRenameInformation*/ == Request->Req.SetInformation.FileInformationClass) ||
+            FspFsctlTransactSetVolumeInformationKind == Request->Kind)
+        {
+            AcquireSRWLockExclusive(&FileSystem->OpGuardLock);
+        }
+        else
+        if (FspFsctlTransactCreateKind == Request->Kind ||
+            (FspFsctlTransactSetInformationKind == Request->Kind &&
+                13/*FileDispositionInformation*/ == Request->Req.SetInformation.FileInformationClass) ||
+            FspFsctlTransactQueryDirectoryKind == Request->Kind ||
+            FspFsctlTransactQueryVolumeInformationKind == Request->Kind)
+        {
+            AcquireSRWLockShared(&FileSystem->OpGuardLock);
+        }
+        break;
+
+    case FSP_FILE_SYSTEM_OPERATION_GUARD_STRATEGY_COARSE:
+        AcquireSRWLockExclusive(&FileSystem->OpGuardLock);
+        break;
+    }
+}
+
+FSP_API VOID FspFileSystemOpLeave(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, FSP_FSCTL_TRANSACT_RSP *Response)
+{
+    switch (FileSystem->OpGuardStrategy)
+    {
+    case FSP_FILE_SYSTEM_OPERATION_GUARD_STRATEGY_FINE:
+        if ((FspFsctlTransactCreateKind == Request->Kind &&
+                FILE_OPEN != ((Request->Req.Create.CreateOptions >> 24) & 0xff)) ||
+            (FspFsctlTransactCleanupKind == Request->Kind &&
+                Request->Req.Cleanup.Delete) ||
+            (FspFsctlTransactSetInformationKind == Request->Kind &&
+                10/*FileRenameInformation*/ == Request->Req.SetInformation.FileInformationClass) ||
+            FspFsctlTransactSetVolumeInformationKind == Request->Kind)
+        {
+            ReleaseSRWLockExclusive(&FileSystem->OpGuardLock);
+        }
+        else
+        if (FspFsctlTransactCreateKind == Request->Kind ||
+            (FspFsctlTransactSetInformationKind == Request->Kind &&
+                13/*FileDispositionInformation*/ == Request->Req.SetInformation.FileInformationClass) ||
+            FspFsctlTransactQueryDirectoryKind == Request->Kind ||
+            FspFsctlTransactQueryVolumeInformationKind == Request->Kind)
+        {
+            ReleaseSRWLockShared(&FileSystem->OpGuardLock);
+        }
+        break;
+
+    case FSP_FILE_SYSTEM_OPERATION_GUARD_STRATEGY_COARSE:
+        ReleaseSRWLockExclusive(&FileSystem->OpGuardLock);
+        break;
+    }
+}
+
 static inline
 NTSTATUS FspFileSystemCreateCheck(FSP_FILE_SYSTEM *FileSystem,
     FSP_FSCTL_TRANSACT_REQ *Request,

src/dll/fuse/fuse.c

@@ -587,12 +587,14 @@ FSP_FUSE_API void fsp_fuse_destroy(struct fsp_fuse_env *env,
     MemFree(f);
 }
 
-FSP_FUSE_API int fsp_fuse_loop(struct fsp_fuse_env *env,
+static int fsp_fuse_loop_internal(struct fsp_fuse_env *env,
-    struct fuse *f)
+    struct fuse *f, FSP_FILE_SYSTEM_OPERATION_GUARD_STRATEGY GuardStrategy)
 {
     NTSTATUS Result;
     ULONG ExitCode;
 
+    FspFileSystemSetOperationGuardStrategy(f->FileSystem, GuardStrategy);
+
     Result = FspServiceLoop(f->Service);
     ExitCode = FspServiceGetExitCode(f->Service);
 
@@ -612,10 +614,18 @@ fail:
     return -1;
 }
 
+FSP_FUSE_API int fsp_fuse_loop(struct fsp_fuse_env *env,
+    struct fuse *f)
+{
+    return fsp_fuse_loop_internal(env, f,
+        FSP_FILE_SYSTEM_OPERATION_GUARD_STRATEGY_COARSE);
+}
+
 FSP_FUSE_API int fsp_fuse_loop_mt(struct fsp_fuse_env *env,
     struct fuse *f)
 {
-    return fsp_fuse_loop(env, f);
+    return fsp_fuse_loop_internal(env, f,
+        FSP_FILE_SYSTEM_OPERATION_GUARD_STRATEGY_FINE);
 }
 
 FSP_FUSE_API void fsp_fuse_exit(struct fsp_fuse_env *env,

tst/memfs/memfs.cpp

@@ -79,7 +79,6 @@ typedef struct _MEMFS
     ULONG MaxFileSize;
     UINT16 VolumeLabelLength;
     WCHAR VolumeLabel[32];
-    CRITICAL_SECTION Lock;
 } MEMFS;
 
 static inline
@@ -962,20 +961,6 @@ static FSP_FILE_SYSTEM_INTERFACE MemfsInterface =
     ReadDirectory,
 };
 
-static VOID MemfsEnterOperation(FSP_FILE_SYSTEM *FileSystem,
-    FSP_FSCTL_TRANSACT_REQ *Request, FSP_FSCTL_TRANSACT_RSP *Response)
-{
-    MEMFS *Memfs = (MEMFS *)FileSystem->UserContext;
-    EnterCriticalSection(&Memfs->Lock);
-}
-
-static VOID MemfsLeaveOperation(FSP_FILE_SYSTEM *FileSystem,
-    FSP_FSCTL_TRANSACT_REQ *Request, FSP_FSCTL_TRANSACT_RSP *Response)
-{
-    MEMFS *Memfs = (MEMFS *)FileSystem->UserContext;
-    LeaveCriticalSection(&Memfs->Lock);
-}
-
 NTSTATUS MemfsCreate(
     ULONG Flags,
     ULONG FileInfoTimeout,
@@ -1050,11 +1035,10 @@ NTSTATUS MemfsCreate(
     Memfs->VolumeLabelLength = sizeof L"MEMFS" - sizeof(WCHAR);
     memcpy(Memfs->VolumeLabel, L"MEMFS", Memfs->VolumeLabelLength);
 
-    InitializeCriticalSection(&Memfs->Lock);
+#if 0
-
+    FspFileSystemSetOperationGuardStrategy(Memfs->FileSystem,
-    FspFileSystemSetOperationGuard(Memfs->FileSystem,
+        FSP_FILE_SYSTEM_OPERATION_GUARD_STRATEGY_COARSE);
-        MemfsEnterOperation,
+#endif
-        MemfsLeaveOperation);
 
     /*
      * Create root directory.
@@ -1099,8 +1083,6 @@ NTSTATUS MemfsCreate(
 
 VOID MemfsDelete(MEMFS *Memfs)
 {
-    DeleteCriticalSection(&Memfs->Lock);
-
     FspFileSystemDelete(Memfs->FileSystem);
 
     MemfsFileNodeMapDelete(Memfs->FileNodeMap);