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-rw-r--r--internal/fusefrontend/file.go86
-rw-r--r--internal/fusefrontend/file_allocate_truncate.go6
-rw-r--r--internal/openfiletable/open_file_table.go18
3 files changed, 45 insertions, 65 deletions
diff --git a/internal/fusefrontend/file.go b/internal/fusefrontend/file.go
index ffc41c6..32f615b 100644
--- a/internal/fusefrontend/file.go
+++ b/internal/fusefrontend/file.go
@@ -145,39 +145,34 @@ func (f *File) createHeader() (fileID []byte, err error) {
//
// Called by Read() for normal reading,
// by Write() and Truncate() via doWrite() for Read-Modify-Write.
-//
-// doWrite() uses nolock=true because it makes sure the ID is in the cache and
-// HeaderLock is locked before calling doRead.
-func (f *File) doRead(dst []byte, off uint64, length uint64, nolock bool) ([]byte, fuse.Status) {
- if !nolock {
- // Make sure we have the file ID.
- f.fileTableEntry.HeaderLock.RLock()
- if f.fileTableEntry.ID == nil {
- f.fileTableEntry.HeaderLock.RUnlock()
- // Yes, somebody else may take the lock before we can. This will get
- // the header read twice, but causes no harm otherwise.
- f.fileTableEntry.HeaderLock.Lock()
- tmpID, err := f.readFileID()
+func (f *File) doRead(dst []byte, off uint64, length uint64) ([]byte, fuse.Status) {
+ // Get the file ID, either from the open file table, or from disk.
+ var fileID []byte
+ f.fileTableEntry.IDLock.Lock()
+ if f.fileTableEntry.ID != nil {
+ // Use the cached value in the file table
+ fileID = f.fileTableEntry.ID
+ } else {
+ // Not cached, we have to read it from disk.
+ var err error
+ fileID, err = f.readFileID()
+ if err != nil {
+ f.fileTableEntry.IDLock.Unlock()
if err == io.EOF {
- f.fileTableEntry.HeaderLock.Unlock()
+ // Empty file
return nil, fuse.OK
}
if err != nil {
- f.fileTableEntry.HeaderLock.Unlock()
tlog.Warn.Printf("doRead %d: corrupt header: %v", f.qIno.Ino, err)
return nil, fuse.EIO
}
- f.fileTableEntry.ID = tmpID
- // Downgrade the lock.
- f.fileTableEntry.HeaderLock.Unlock()
- // The file ID may change in here. This does no harm because we
- // re-read it after the RLock().
- f.fileTableEntry.HeaderLock.RLock()
}
+ // Save into the file table
+ f.fileTableEntry.ID = fileID
}
- fileID := f.fileTableEntry.ID
+ f.fileTableEntry.IDLock.Unlock()
if fileID == nil {
- log.Panicf("filedID=%v, nolock=%v", fileID, nolock)
+ log.Panicf("fileID=%v", fileID)
}
// Read the backing ciphertext in one go
blocks := f.contentEnc.ExplodePlainRange(off, length)
@@ -189,10 +184,6 @@ func (f *File) doRead(dst []byte, off uint64, length uint64, nolock bool) ([]byt
ciphertext := f.fs.contentEnc.CReqPool.Get()
ciphertext = ciphertext[:int(alignedLength)]
n, err := f.fd.ReadAt(ciphertext, int64(alignedOffset))
- // We don't care if the file ID changes after we have read the data. Drop the lock.
- if !nolock {
- f.fileTableEntry.HeaderLock.RUnlock()
- }
if err != nil && err != io.EOF {
tlog.Warn.Printf("read: ReadAt: %s", err.Error())
return nil, fuse.ToStatus(err)
@@ -251,11 +242,14 @@ func (f *File) Read(buf []byte, off int64) (resultData fuse.ReadResult, code fus
f.fdLock.RLock()
defer f.fdLock.RUnlock()
+ f.fileTableEntry.ContentLock.RLock()
+ defer f.fileTableEntry.ContentLock.RUnlock()
+
tlog.Debug.Printf("ino%d: FUSE Read: offset=%d length=%d", f.qIno.Ino, len(buf), off)
if f.fs.args.SerializeReads {
serialize_reads.Wait(off, len(buf))
}
- out, status := f.doRead(buf[:0], uint64(off), uint64(len(buf)), false)
+ out, status := f.doRead(buf[:0], uint64(off), uint64(len(buf)))
if f.fs.args.SerializeReads {
serialize_reads.Done()
}
@@ -277,31 +271,25 @@ func (f *File) Read(buf []byte, off int64) (resultData fuse.ReadResult, code fus
// Empty writes do nothing and are allowed.
func (f *File) doWrite(data []byte, off int64) (uint32, fuse.Status) {
fileWasEmpty := false
- // If the file ID is not cached, read it from disk
- if f.fileTableEntry.ID == nil {
- // Block other readers while we mess with the file header. Other writers
- // are blocked by ContentLock already.
- f.fileTableEntry.HeaderLock.Lock()
- tmpID, err := f.readFileID()
+ // Get the file ID, create a new one if it does not exist yet.
+ var fileID []byte
+ // The caller has exclusively locked ContentLock, which blocks all other
+ // readers and writers. No need to take IDLock.
+ if f.fileTableEntry.ID != nil {
+ fileID = f.fileTableEntry.ID
+ } else {
+ // If the file ID is not cached, read it from disk
+ var err error
+ fileID, err = f.readFileID()
// Write a new file header if the file is empty
if err == io.EOF {
- tmpID, err = f.createHeader()
+ fileID, err = f.createHeader()
fileWasEmpty = true
}
if err != nil {
- f.fileTableEntry.HeaderLock.Unlock()
return 0, fuse.ToStatus(err)
}
- f.fileTableEntry.ID = tmpID
- if fileWasEmpty {
- // The file was empty and we wrote a new file header. Keep the lock
- // as we might have to kill the file header again if the data write
- // fails.
- defer f.fileTableEntry.HeaderLock.Unlock()
- } else {
- // We won't touch the header again, drop the lock immediately.
- f.fileTableEntry.HeaderLock.Unlock()
- }
+ f.fileTableEntry.ID = fileID
}
// Handle payload data
dataBuf := bytes.NewBuffer(data)
@@ -312,7 +300,7 @@ func (f *File) doWrite(data []byte, off int64) (uint32, fuse.Status) {
// Incomplete block -> Read-Modify-Write
if b.IsPartial() {
// Read
- oldData, status := f.doRead(nil, b.BlockPlainOff(), f.contentEnc.PlainBS(), true)
+ oldData, status := f.doRead(nil, b.BlockPlainOff(), f.contentEnc.PlainBS())
if status != fuse.OK {
tlog.Warn.Printf("ino%d fh%d: RMW read failed: %s", f.qIno.Ino, f.intFd(), status.String())
return 0, status
@@ -382,9 +370,7 @@ func (f *File) Write(data []byte, off int64) (uint32, fuse.Status) {
f.fdLock.RLock()
defer f.fdLock.RUnlock()
if f.released {
- // The file descriptor has been closed concurrently, which also means
- // the wlock has been freed. Exit here so we don't crash trying to access
- // it.
+ // The file descriptor has been closed concurrently
tlog.Warn.Printf("ino%d fh%d: Write on released file", f.qIno.Ino, f.intFd())
return 0, fuse.EBADF
}
diff --git a/internal/fusefrontend/file_allocate_truncate.go b/internal/fusefrontend/file_allocate_truncate.go
index 81ac8d3..34fe2c0 100644
--- a/internal/fusefrontend/file_allocate_truncate.go
+++ b/internal/fusefrontend/file_allocate_truncate.go
@@ -111,9 +111,7 @@ func (f *File) Truncate(newSize uint64) fuse.Status {
return fuse.ToStatus(err)
}
// Truncate to zero kills the file header
- f.fileTableEntry.HeaderLock.Lock()
f.fileTableEntry.ID = nil
- f.fileTableEntry.HeaderLock.Unlock()
return fuse.OK
}
// We need the old file size to determine if we are growing or shrinking
@@ -144,7 +142,7 @@ func (f *File) Truncate(newSize uint64) fuse.Status {
var data []byte
if lastBlockLen > 0 {
var status fuse.Status
- data, status = f.doRead(nil, plainOff, lastBlockLen, false)
+ data, status = f.doRead(nil, plainOff, lastBlockLen)
if status != fuse.OK {
tlog.Warn.Printf("Truncate: shrink doRead returned error: %v", err)
return status
@@ -206,8 +204,6 @@ func (f *File) truncateGrowFile(oldPlainSz uint64, newPlainSz uint64) fuse.Statu
if newPlainSz%f.contentEnc.PlainBS() == 0 {
// The file was empty, so it did not have a header. Create one.
if oldPlainSz == 0 {
- f.fileTableEntry.HeaderLock.Lock()
- defer f.fileTableEntry.HeaderLock.Unlock()
id, err := f.createHeader()
if err != nil {
return fuse.ToStatus(err)
diff --git a/internal/openfiletable/open_file_table.go b/internal/openfiletable/open_file_table.go
index d70bcfa..e21c96d 100644
--- a/internal/openfiletable/open_file_table.go
+++ b/internal/openfiletable/open_file_table.go
@@ -57,18 +57,16 @@ type table struct {
// Entry is an entry in the open file table
type Entry struct {
- // Reference count
+ // Reference count. Protected by the table lock.
refCount int
- // ContentLock guards the file content from concurrent writes. Every writer
+ // ContentLock protects on-disk content from concurrent writes. Every writer
// must take this lock before modifying the file content.
ContentLock countingMutex
- // HeaderLock guards the file ID (in this struct) and the file header (on
- // disk). Take HeaderLock.RLock() to make sure the file ID does not change
- // behind your back. If you modify the file ID, you must take
- // HeaderLock.Lock().
- HeaderLock sync.RWMutex
// ID is the file ID in the file header.
ID []byte
+ // IDLock must be taken before reading or writing the ID field in this struct,
+ // unless you have an exclusive lock on ContentLock.
+ IDLock sync.Mutex
}
// Register creates an open file table entry for "qi" (or incrementes the
@@ -101,15 +99,15 @@ func Unregister(qi QIno) {
// countingMutex incrementes t.writeLockCount on each Lock() call.
type countingMutex struct {
- sync.Mutex
+ sync.RWMutex
}
func (c *countingMutex) Lock() {
- c.Mutex.Lock()
+ c.RWMutex.Lock()
atomic.AddUint64(&t.writeOpCount, 1)
}
-// WriteOpCount returns the write lock counter value. This value is encremented
+// WriteOpCount returns the write lock counter value. This value is incremented
// each time writeLock.Lock() on a file table entry is called.
func WriteOpCount() uint64 {
return atomic.LoadUint64(&t.writeOpCount)
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-08 16:15:59 +0000