Rejiggered the ReadFile and ReadDir API.
The new API lends itself toward reading directly into the output buffer, saving a memmove and allowing for easy reuse of output buffers.geesefs-0-30-9
Aaron Jacobs
commit
4fd46371a2
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@ -252,7 +252,7 @@ func convertInMessage(
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Inode: fuseops.InodeID(m.Header().Nodeid),
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Handle: fuseops.HandleID(in.Fh),
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Offset: int64(in.Offset),
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Size: int(in.Size),
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Dst: make([]byte, in.Size),
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}
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case fusekernel.OpReaddir:
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@ -266,7 +266,7 @@ func convertInMessage(
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Inode: fuseops.InodeID(m.Header().Nodeid),
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Handle: fuseops.HandleID(in.Fh),
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Offset: fuseops.DirOffset(in.Offset),
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Size: int(in.Size),
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Dst: make([]byte, in.Size),
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}
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case fusekernel.OpRelease:
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@ -486,7 +486,7 @@ func (c *Connection) kernelResponseForOp(
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case *fuseops.ReadDirOp:
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m = c.getOutMessage()
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m.Append(o.Data)
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m.Append(o.Dst[:o.BytesRead])
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case *fuseops.ReleaseDirHandleOp:
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m = c.getOutMessage()
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@ -498,7 +498,7 @@ func (c *Connection) kernelResponseForOp(
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case *fuseops.ReadFileOp:
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m = c.getOutMessage()
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m.Append(o.Data)
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m.Append(o.Dst[:o.BytesRead])
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case *fuseops.WriteFileOp:
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m = c.getOutMessage()
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@ -384,25 +384,29 @@ type ReadDirOp struct {
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// offset, and return array offsets into that cached listing.
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Offset DirOffset
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// The maximum number of bytes to return in ReadDirResponse.Data. A smaller
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// number is acceptable.
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Size int
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// Set by the file system: a buffer consisting of a sequence of FUSE
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// directory entries in the format generated by fuse_add_direntry
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// (http://goo.gl/qCcHCV), which is consumed by parse_dirfile
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// (http://goo.gl/2WUmD2). Use fuseutil.AppendDirent to generate this data.
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// The destination buffer, whose length gives the size of the read.
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//
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// The buffer must not exceed the length specified in ReadDirRequest.Size. It
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// is okay for the final entry to be truncated; parse_dirfile copes with this
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// by ignoring the partial record.
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// The output data should consist of a sequence of FUSE directory entries in
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// the format generated by fuse_add_direntry (http://goo.gl/qCcHCV), which is
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// consumed by parse_dirfile (http://goo.gl/2WUmD2). Use fuseutil.WriteDirent
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// to generate this data.
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//
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// Each entry returned exposes a directory offset to the user that may later
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// show up in ReadDirRequest.Offset. See notes on that field for more
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// information.
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Dst []byte
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// Set by the file system: the number of bytes read into Dst.
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//
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// An empty buffer indicates the end of the directory has been reached.
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Data []byte
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// It is okay for this to be less than len(Dst) if there are not enough
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// entries available or the final entry would not fit.
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//
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// Zero means that the end of the directory has been reached. This is
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// unambiguous because NAME_MAX (https://goo.gl/ZxzKaE) plus the size of
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// fuse_dirent (https://goo.gl/WO8s3F) plus the 8-byte alignment of
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// FUSE_DIRENT_ALIGN (http://goo.gl/UziWvH) is less than the read size of
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// PAGE_SIZE used by fuse_readdir (cf. https://goo.gl/VajtS2).
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BytesRead int
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}
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// Release a previously-minted directory handle. The kernel sends this when
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@ -455,20 +459,21 @@ type ReadFileOp struct {
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Inode InodeID
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Handle HandleID
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// The range of the file to read.
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// The offset within the file at which to read.
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Offset int64
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// The destination buffer, whose length gives the size of the read.
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Dst []byte
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// Set by the file system: the number of bytes read.
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//
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// The FUSE documentation requires that exactly the number of bytes be
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// returned, except in the case of EOF or error (http://goo.gl/ZgfBkF). This
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// appears to be because it uses file mmapping machinery
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// The FUSE documentation requires that exactly the requested number of bytes
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// be returned, except in the case of EOF or error (http://goo.gl/ZgfBkF).
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// This appears to be because it uses file mmapping machinery
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// (http://goo.gl/SGxnaN) to read a page at a time. It appears to understand
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// where EOF is by checking the inode size (http://goo.gl/0BkqKD), returned
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// by a previous call to LookUpInode, GetInodeAttributes, etc.
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Offset int64
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Size int
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// Set by the file system: the data read. If this is less than the requested
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// size, it indicates EOF. An error should not be returned in this case.
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Data []byte
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BytesRead int
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}
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// Write data to a file previously opened with CreateFile or OpenFile.
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@ -35,7 +35,7 @@ const (
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)
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// A struct representing an entry within a directory file, describing a child.
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// See notes on fuseops.ReadDirOp and on AppendDirent for details.
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// See notes on fuseops.ReadDirOp and on WriteDirent for details.
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type Dirent struct {
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// The (opaque) offset within the directory file of the entry following this
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// one. See notes on fuseops.ReadDirOp.Offset for details.
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@ -50,10 +50,11 @@ type Dirent struct {
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Type DirentType
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}
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// Append the supplied directory entry to the given buffer in the format
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// expected in fuseops.ReadFileOp.Data, returning the resulting buffer.
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func AppendDirent(input []byte, d Dirent) (output []byte) {
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// We want to append bytes with the layout of fuse_dirent
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// Write the supplied directory entry intto the given buffer in the format
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// expected in fuseops.ReadFileOp.Data, returning the number of bytes written.
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// Return zero if the entry would not fit.
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func WriteDirent(buf []byte, d Dirent) (n int) {
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// We want to write bytes with the layout of fuse_dirent
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// (http://goo.gl/BmFxob) in host order. The struct must be aligned according
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// to FUSE_DIRENT_ALIGN (http://goo.gl/UziWvH), which dictates 8-byte
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// alignment.
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@ -65,10 +66,23 @@ func AppendDirent(input []byte, d Dirent) (output []byte) {
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name [0]byte
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}
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const alignment = 8
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const nameOffset = 8 + 8 + 4 + 4
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const direntAlignment = 8
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const direntSize = 8 + 8 + 4 + 4
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// Write the header into the buffer.
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// Compute the number of bytes of padding we'll need to maintain alignment
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// for the next entry.
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var padLen int
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if len(d.Name)%direntAlignment != 0 {
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padLen = direntAlignment - (len(d.Name) % direntAlignment)
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}
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// Do we have enough room?
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totalLen := direntSize + len(d.Name) + padLen
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if totalLen > len(buf) {
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return
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}
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// Write the header.
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de := fuse_dirent{
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ino: uint64(d.Inode),
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off: uint64(d.Offset),
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@ -76,17 +90,15 @@ func AppendDirent(input []byte, d Dirent) (output []byte) {
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type_: uint32(d.Type),
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}
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output = append(input, (*[nameOffset]byte)(unsafe.Pointer(&de))[:]...)
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n += copy(buf[n:], (*[direntSize]byte)(unsafe.Pointer(&de))[:])
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// Write the name afterward.
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output = append(output, d.Name...)
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n += copy(buf[n:], d.Name)
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// Add any necessary padding.
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if len(d.Name)%alignment != 0 {
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padLen := alignment - (len(d.Name) % alignment)
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var padding [alignment]byte
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output = append(output, padding[:padLen]...)
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if padLen != 0 {
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var padding [direntAlignment]byte
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n += copy(buf[n:], padding[:padLen])
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}
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return
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@ -180,8 +180,7 @@ func (fs *flushFS) ReadFile(
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}
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// Read what we can.
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op.Data = make([]byte, op.Size)
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copy(op.Data, fs.fooContents[op.Offset:])
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op.BytesRead = copy(op.Dst, fs.fooContents[op.Offset:])
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return
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}
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@ -298,13 +297,15 @@ func (fs *flushFS) ReadDir(
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// Fill in the listing.
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for _, de := range dirents {
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op.Data = fuseutil.AppendDirent(op.Data, de)
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}
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n := fuseutil.WriteDirent(op.Dst[op.BytesRead:], de)
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// We don't support doing this in anything more than one shot.
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if len(op.Data) > op.Size {
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err = fmt.Errorf("Couldn't fit listing in %v bytes", op.Size)
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return
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// We don't support doing this in anything more than one shot.
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if n == 0 {
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err = fmt.Errorf("Couldn't fit listing in %v bytes", len(op.Dst))
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return
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}
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op.BytesRead += n
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}
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return
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@ -228,11 +228,12 @@ func (fs *helloFS) ReadDir(
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// Resume at the specified offset into the array.
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for _, e := range entries {
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op.Data = fuseutil.AppendDirent(op.Data, e)
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if len(op.Data) > op.Size {
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op.Data = op.Data[:op.Size]
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n := fuseutil.WriteDirent(op.Dst[op.BytesRead:], e)
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if n == 0 {
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break
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}
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op.BytesRead += n
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}
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return
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@ -251,9 +252,7 @@ func (fs *helloFS) ReadFile(
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// Let io.ReaderAt deal with the semantics.
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reader := strings.NewReader("Hello, world!")
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op.Data = make([]byte, op.Size)
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n, err := reader.ReadAt(op.Data, op.Offset)
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op.Data = op.Data[:n]
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op.BytesRead, err = reader.ReadAt(op.Dst, op.Offset)
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// Special case: FUSE doesn't expect us to return io.EOF.
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if err == io.EOF {
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@ -278,7 +278,7 @@ func (in *inode) RemoveChild(name string) {
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// Serve a ReadDir request.
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//
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// REQUIRES: in.isDir()
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func (in *inode) ReadDir(offset int, size int) (data []byte) {
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func (in *inode) ReadDir(p []byte, offset int) (n int) {
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if !in.isDir() {
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panic("ReadDir called on non-directory.")
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}
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@ -291,13 +291,12 @@ func (in *inode) ReadDir(offset int, size int) (data []byte) {
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continue
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}
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data = fuseutil.AppendDirent(data, in.entries[i])
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// Trim and stop early if we've exceeded the requested size.
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if len(data) > size {
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data = data[:size]
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tmp := fuseutil.WriteDirent(p[n:], in.entries[i])
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if tmp == 0 {
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break
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}
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n += tmp
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}
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return
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@ -428,7 +428,9 @@ func (fs *memFS) Rename(
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existingID, _, ok := newParent.LookUpChild(op.NewName)
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if ok {
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existing := fs.getInodeOrDie(existingID)
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if existing.isDir() && len(existing.ReadDir(0, 1024)) > 0 {
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var buf [4096]byte
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if existing.isDir() && existing.ReadDir(buf[:], 0) > 0 {
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err = fuse.ENOTEMPTY
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return
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}
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@ -538,7 +540,7 @@ func (fs *memFS) ReadDir(
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inode := fs.getInodeOrDie(op.Inode)
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// Serve the request.
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op.Data = inode.ReadDir(int(op.Offset), op.Size)
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op.BytesRead = inode.ReadDir(op.Dst, int(op.Offset))
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return
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}
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@ -571,9 +573,7 @@ func (fs *memFS) ReadFile(
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inode := fs.getInodeOrDie(op.Inode)
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// Serve the request.
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op.Data = make([]byte, op.Size)
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n, err := inode.ReadAt(op.Data, op.Offset)
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op.Data = op.Data[:n]
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op.BytesRead, err = inode.ReadAt(op.Dst, op.Offset)
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// Don't return EOF errors; we just indicate EOF to fuse using a short read.
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if err == io.EOF {
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