12876: Merge branch 'master' into 12876-arvados-client
[arvados.git] / sdk / go / arvados / collection_fs.go
index 367f6d003c3c15db529fa9328caf1f154a369ad3..d8ee2a2b1c5175697bf39369274ff6c0a42e7310 100644 (file)
@@ -34,6 +34,8 @@ var (
        maxBlockSize = 1 << 26
 )
 
+// A File is an *os.File-like interface for reading and writing files
+// in a CollectionFileSystem.
 type File interface {
        io.Reader
        io.Writer
@@ -118,6 +120,11 @@ type CollectionFileSystem interface {
        Remove(name string) error
        RemoveAll(name string) error
        Rename(oldname, newname string) error
+
+       // Flush all file data to Keep and return a snapshot of the
+       // filesystem suitable for saving as (Collection)ManifestText.
+       // Prefix (normally ".") is a top level directory, effectively
+       // prepended to all paths in the returned manifest.
        MarshalManifest(prefix string) (string, error)
 }
 
@@ -126,24 +133,25 @@ type fileSystem struct {
 }
 
 func (fs *fileSystem) OpenFile(name string, flag int, perm os.FileMode) (File, error) {
-       return fs.dirnode.OpenFile(path.Clean(name), flag, perm)
+       return fs.dirnode.OpenFile(name, flag, perm)
 }
 
 func (fs *fileSystem) Open(name string) (http.File, error) {
-       return fs.dirnode.OpenFile(path.Clean(name), os.O_RDONLY, 0)
+       return fs.dirnode.OpenFile(name, os.O_RDONLY, 0)
 }
 
 func (fs *fileSystem) Create(name string) (File, error) {
-       return fs.dirnode.OpenFile(path.Clean(name), os.O_CREATE|os.O_RDWR|os.O_TRUNC, 0)
+       return fs.dirnode.OpenFile(name, os.O_CREATE|os.O_RDWR|os.O_TRUNC, 0)
 }
 
-func (fs *fileSystem) Stat(name string) (os.FileInfo, error) {
-       f, err := fs.OpenFile(name, os.O_RDONLY, 0)
-       if err != nil {
-               return nil, err
+func (fs *fileSystem) Stat(name string) (fi os.FileInfo, err error) {
+       node := fs.dirnode.lookupPath(name)
+       if node == nil {
+               err = os.ErrNotExist
+       } else {
+               fi = node.Stat()
        }
-       defer f.Close()
-       return f.Stat()
+       return
 }
 
 type inode interface {
@@ -163,54 +171,57 @@ type inode interface {
 type filenode struct {
        fileinfo fileinfo
        parent   *dirnode
-       extents  []extent
-       repacked int64 // number of times anything in []extents has changed len
-       memsize  int64 // bytes in memExtents
+       segments []segment
+       // number of times `segments` has changed in a
+       // way that might invalidate a filenodePtr
+       repacked int64
+       memsize  int64 // bytes in memSegments
        sync.RWMutex
 }
 
 // filenodePtr is an offset into a file that is (usually) efficient to
 // seek to. Specifically, if filenode.repacked==filenodePtr.repacked
-// then filenode.extents[filenodePtr.extentIdx][filenodePtr.extentOff]
+// then
+// filenode.segments[filenodePtr.segmentIdx][filenodePtr.segmentOff]
 // corresponds to file offset filenodePtr.off. Otherwise, it is
-// necessary to reexamine len(filenode.extents[0]) etc. to find the
-// correct extent and offset.
+// necessary to reexamine len(filenode.segments[0]) etc. to find the
+// correct segment and offset.
 type filenodePtr struct {
-       off       int64
-       extentIdx int
-       extentOff int
-       repacked  int64
+       off        int64
+       segmentIdx int
+       segmentOff int
+       repacked   int64
 }
 
 // seek returns a ptr that is consistent with both startPtr.off and
 // the current state of fn. The caller must already hold fn.RLock() or
 // fn.Lock().
 //
-// If startPtr points beyond the end of the file, ptr will point to
-// exactly the end of the file.
+// If startPtr is beyond EOF, ptr.segment* will indicate precisely
+// EOF.
 //
 // After seeking:
 //
-//     ptr.extentIdx == len(filenode.extents) // i.e., at EOF
+//     ptr.segmentIdx == len(filenode.segments) // i.e., at EOF
 //     ||
-//     filenode.extents[ptr.extentIdx].Len() >= ptr.extentOff
+//     filenode.segments[ptr.segmentIdx].Len() > ptr.segmentOff
 func (fn *filenode) seek(startPtr filenodePtr) (ptr filenodePtr) {
        ptr = startPtr
        if ptr.off < 0 {
                // meaningless anyway
                return
        } else if ptr.off >= fn.fileinfo.size {
-               ptr.off = fn.fileinfo.size
-               ptr.extentIdx = len(fn.extents)
-               ptr.extentOff = 0
+               ptr.segmentIdx = len(fn.segments)
+               ptr.segmentOff = 0
                ptr.repacked = fn.repacked
                return
        } else if ptr.repacked == fn.repacked {
-               // extentIdx and extentOff accurately reflect ptr.off,
-               // but might have fallen off the end of an extent
-               if ptr.extentOff >= fn.extents[ptr.extentIdx].Len() {
-                       ptr.extentIdx++
-                       ptr.extentOff = 0
+               // segmentIdx and segmentOff accurately reflect
+               // ptr.off, but might have fallen off the end of a
+               // segment
+               if ptr.segmentOff >= fn.segments[ptr.segmentIdx].Len() {
+                       ptr.segmentIdx++
+                       ptr.segmentOff = 0
                }
                return
        }
@@ -218,37 +229,38 @@ func (fn *filenode) seek(startPtr filenodePtr) (ptr filenodePtr) {
                ptr.repacked = fn.repacked
        }()
        if ptr.off >= fn.fileinfo.size {
-               ptr.extentIdx, ptr.extentOff = len(fn.extents), 0
+               ptr.segmentIdx, ptr.segmentOff = len(fn.segments), 0
                return
        }
-       // Recompute extentIdx and extentOff.  We have already
+       // Recompute segmentIdx and segmentOff.  We have already
        // established fn.fileinfo.size > ptr.off >= 0, so we don't
        // have to deal with edge cases here.
        var off int64
-       for ptr.extentIdx, ptr.extentOff = 0, 0; off < ptr.off; ptr.extentIdx++ {
+       for ptr.segmentIdx, ptr.segmentOff = 0, 0; off < ptr.off; ptr.segmentIdx++ {
                // This would panic (index out of range) if
                // fn.fileinfo.size were larger than
-               // sum(fn.extents[i].Len()) -- but that can't happen
+               // sum(fn.segments[i].Len()) -- but that can't happen
                // because we have ensured fn.fileinfo.size is always
                // accurate.
-               extLen := int64(fn.extents[ptr.extentIdx].Len())
-               if off+extLen > ptr.off {
-                       ptr.extentOff = int(ptr.off - off)
+               segLen := int64(fn.segments[ptr.segmentIdx].Len())
+               if off+segLen > ptr.off {
+                       ptr.segmentOff = int(ptr.off - off)
                        break
                }
-               off += extLen
+               off += segLen
        }
        return
 }
 
-func (fn *filenode) appendExtent(e extent) {
-       fn.Lock()
-       defer fn.Unlock()
-       fn.extents = append(fn.extents, e)
+// caller must have lock
+func (fn *filenode) appendSegment(e segment) {
+       fn.segments = append(fn.segments, e)
        fn.fileinfo.size += int64(e.Len())
 }
 
 func (fn *filenode) Parent() inode {
+       fn.RLock()
+       defer fn.RUnlock()
        return fn.parent
 }
 
@@ -256,24 +268,27 @@ func (fn *filenode) Readdir() []os.FileInfo {
        return nil
 }
 
+// Read reads file data from a single segment, starting at startPtr,
+// into p. startPtr is assumed not to be up-to-date. Caller must have
+// RLock or Lock.
 func (fn *filenode) Read(p []byte, startPtr filenodePtr) (n int, ptr filenodePtr, err error) {
        ptr = fn.seek(startPtr)
        if ptr.off < 0 {
                err = ErrNegativeOffset
                return
        }
-       if ptr.extentIdx >= len(fn.extents) {
+       if ptr.segmentIdx >= len(fn.segments) {
                err = io.EOF
                return
        }
-       n, err = fn.extents[ptr.extentIdx].ReadAt(p, int64(ptr.extentOff))
+       n, err = fn.segments[ptr.segmentIdx].ReadAt(p, int64(ptr.segmentOff))
        if n > 0 {
                ptr.off += int64(n)
-               ptr.extentOff += n
-               if ptr.extentOff == fn.extents[ptr.extentIdx].Len() {
-                       ptr.extentIdx++
-                       ptr.extentOff = 0
-                       if ptr.extentIdx < len(fn.extents) && err == io.EOF {
+               ptr.segmentOff += n
+               if ptr.segmentOff == fn.segments[ptr.segmentIdx].Len() {
+                       ptr.segmentIdx++
+                       ptr.segmentOff = 0
+                       if ptr.segmentIdx < len(fn.segments) && err == io.EOF {
                                err = nil
                        }
                }
@@ -296,53 +311,65 @@ func (fn *filenode) Stat() os.FileInfo {
 func (fn *filenode) Truncate(size int64) error {
        fn.Lock()
        defer fn.Unlock()
+       return fn.truncate(size)
+}
+
+func (fn *filenode) truncate(size int64) error {
+       if size == fn.fileinfo.size {
+               return nil
+       }
+       fn.repacked++
        if size < fn.fileinfo.size {
-               ptr := fn.seek(filenodePtr{off: size, repacked: fn.repacked - 1})
-               for i := ptr.extentIdx; i < len(fn.extents); i++ {
-                       if ext, ok := fn.extents[i].(*memExtent); ok {
-                               fn.memsize -= int64(ext.Len())
+               ptr := fn.seek(filenodePtr{off: size})
+               for i := ptr.segmentIdx; i < len(fn.segments); i++ {
+                       if seg, ok := fn.segments[i].(*memSegment); ok {
+                               fn.memsize -= int64(seg.Len())
                        }
                }
-               if ptr.extentOff == 0 {
-                       fn.extents = fn.extents[:ptr.extentIdx]
+               if ptr.segmentOff == 0 {
+                       fn.segments = fn.segments[:ptr.segmentIdx]
                } else {
-                       fn.extents = fn.extents[:ptr.extentIdx+1]
-                       switch ext := fn.extents[ptr.extentIdx].(type) {
-                       case *memExtent:
-                               ext.Truncate(ptr.extentOff)
-                               fn.memsize += int64(ext.Len())
+                       fn.segments = fn.segments[:ptr.segmentIdx+1]
+                       switch seg := fn.segments[ptr.segmentIdx].(type) {
+                       case *memSegment:
+                               seg.Truncate(ptr.segmentOff)
+                               fn.memsize += int64(seg.Len())
                        default:
-                               fn.extents[ptr.extentIdx] = ext.Slice(0, ptr.extentOff)
+                               fn.segments[ptr.segmentIdx] = seg.Slice(0, ptr.segmentOff)
                        }
                }
                fn.fileinfo.size = size
-               fn.repacked++
                return nil
        }
        for size > fn.fileinfo.size {
                grow := size - fn.fileinfo.size
-               var e writableExtent
+               var seg *memSegment
                var ok bool
-               if len(fn.extents) == 0 {
-                       e = &memExtent{}
-                       fn.extents = append(fn.extents, e)
-               } else if e, ok = fn.extents[len(fn.extents)-1].(writableExtent); !ok || e.Len() >= maxBlockSize {
-                       e = &memExtent{}
-                       fn.extents = append(fn.extents, e)
-               } else {
-                       fn.repacked++
+               if len(fn.segments) == 0 {
+                       seg = &memSegment{}
+                       fn.segments = append(fn.segments, seg)
+               } else if seg, ok = fn.segments[len(fn.segments)-1].(*memSegment); !ok || seg.Len() >= maxBlockSize {
+                       seg = &memSegment{}
+                       fn.segments = append(fn.segments, seg)
                }
-               if maxgrow := int64(maxBlockSize - e.Len()); maxgrow < grow {
+               if maxgrow := int64(maxBlockSize - seg.Len()); maxgrow < grow {
                        grow = maxgrow
                }
-               e.Truncate(e.Len() + int(grow))
+               seg.Truncate(seg.Len() + int(grow))
                fn.fileinfo.size += grow
                fn.memsize += grow
        }
        return nil
 }
 
+// Write writes data from p to the file, starting at startPtr,
+// extending the file size if necessary. Caller must have Lock.
 func (fn *filenode) Write(p []byte, startPtr filenodePtr) (n int, ptr filenodePtr, err error) {
+       if startPtr.off > fn.fileinfo.size {
+               if err = fn.truncate(startPtr.off); err != nil {
+                       return 0, startPtr, err
+               }
+       }
        ptr = fn.seek(startPtr)
        if ptr.off < 0 {
                err = ErrNegativeOffset
@@ -353,160 +380,175 @@ func (fn *filenode) Write(p []byte, startPtr filenodePtr) (n int, ptr filenodePt
                if len(cando) > maxBlockSize {
                        cando = cando[:maxBlockSize]
                }
-               // Rearrange/grow fn.extents (and shrink cando if
+               // Rearrange/grow fn.segments (and shrink cando if
                // needed) such that cando can be copied to
-               // fn.extents[ptr.extentIdx] at offset ptr.extentOff.
-               cur := ptr.extentIdx
-               prev := ptr.extentIdx - 1
+               // fn.segments[ptr.segmentIdx] at offset
+               // ptr.segmentOff.
+               cur := ptr.segmentIdx
+               prev := ptr.segmentIdx - 1
                var curWritable bool
-               if cur < len(fn.extents) {
-                       _, curWritable = fn.extents[cur].(writableExtent)
+               if cur < len(fn.segments) {
+                       _, curWritable = fn.segments[cur].(*memSegment)
                }
                var prevAppendable bool
-               if prev >= 0 && fn.extents[prev].Len() < maxBlockSize {
-                       _, prevAppendable = fn.extents[prev].(writableExtent)
+               if prev >= 0 && fn.segments[prev].Len() < maxBlockSize {
+                       _, prevAppendable = fn.segments[prev].(*memSegment)
                }
-               if ptr.extentOff > 0 && !curWritable {
+               if ptr.segmentOff > 0 && !curWritable {
                        // Split a non-writable block.
-                       if max := fn.extents[cur].Len() - ptr.extentOff; max <= len(cando) {
+                       if max := fn.segments[cur].Len() - ptr.segmentOff; max <= len(cando) {
                                // Truncate cur, and insert a new
-                               // extent after it.
+                               // segment after it.
                                cando = cando[:max]
-                               fn.extents = append(fn.extents, nil)
-                               copy(fn.extents[cur+1:], fn.extents[cur:])
+                               fn.segments = append(fn.segments, nil)
+                               copy(fn.segments[cur+1:], fn.segments[cur:])
                        } else {
                                // Split cur into two copies, truncate
                                // the one on the left, shift the one
                                // on the right, and insert a new
-                               // extent between them.
-                               fn.extents = append(fn.extents, nil, nil)
-                               copy(fn.extents[cur+2:], fn.extents[cur:])
-                               fn.extents[cur+2] = fn.extents[cur+2].Slice(ptr.extentOff+len(cando), -1)
+                               // segment between them.
+                               fn.segments = append(fn.segments, nil, nil)
+                               copy(fn.segments[cur+2:], fn.segments[cur:])
+                               fn.segments[cur+2] = fn.segments[cur+2].Slice(ptr.segmentOff+len(cando), -1)
                        }
                        cur++
                        prev++
-                       e := &memExtent{}
-                       e.Truncate(len(cando))
+                       seg := &memSegment{}
+                       seg.Truncate(len(cando))
                        fn.memsize += int64(len(cando))
-                       fn.extents[cur] = e
-                       fn.extents[prev] = fn.extents[prev].Slice(0, ptr.extentOff)
-                       ptr.extentIdx++
-                       ptr.extentOff = 0
+                       fn.segments[cur] = seg
+                       fn.segments[prev] = fn.segments[prev].Slice(0, ptr.segmentOff)
+                       ptr.segmentIdx++
+                       ptr.segmentOff = 0
                        fn.repacked++
                        ptr.repacked++
                } else if curWritable {
-                       if fit := int(fn.extents[cur].Len()) - ptr.extentOff; fit < len(cando) {
+                       if fit := int(fn.segments[cur].Len()) - ptr.segmentOff; fit < len(cando) {
                                cando = cando[:fit]
                        }
                } else {
                        if prevAppendable {
-                               // Shrink cando if needed to fit in prev extent.
-                               if cangrow := maxBlockSize - fn.extents[prev].Len(); cangrow < len(cando) {
+                               // Shrink cando if needed to fit in
+                               // prev segment.
+                               if cangrow := maxBlockSize - fn.segments[prev].Len(); cangrow < len(cando) {
                                        cando = cando[:cangrow]
                                }
                        }
 
-                       if cur == len(fn.extents) {
+                       if cur == len(fn.segments) {
                                // ptr is at EOF, filesize is changing.
                                fn.fileinfo.size += int64(len(cando))
-                       } else if el := fn.extents[cur].Len(); el <= len(cando) {
+                       } else if el := fn.segments[cur].Len(); el <= len(cando) {
                                // cando is long enough that we won't
                                // need cur any more. shrink cando to
                                // be exactly as long as cur
                                // (otherwise we'd accidentally shift
                                // the effective position of all
-                               // extents after cur).
+                               // segments after cur).
                                cando = cando[:el]
-                               copy(fn.extents[cur:], fn.extents[cur+1:])
-                               fn.extents = fn.extents[:len(fn.extents)-1]
+                               copy(fn.segments[cur:], fn.segments[cur+1:])
+                               fn.segments = fn.segments[:len(fn.segments)-1]
                        } else {
                                // shrink cur by the same #bytes we're growing prev
-                               fn.extents[cur] = fn.extents[cur].Slice(len(cando), -1)
+                               fn.segments[cur] = fn.segments[cur].Slice(len(cando), -1)
                        }
 
                        if prevAppendable {
                                // Grow prev.
-                               ptr.extentIdx--
-                               ptr.extentOff = fn.extents[prev].Len()
-                               fn.extents[prev].(writableExtent).Truncate(ptr.extentOff + len(cando))
+                               ptr.segmentIdx--
+                               ptr.segmentOff = fn.segments[prev].Len()
+                               fn.segments[prev].(*memSegment).Truncate(ptr.segmentOff + len(cando))
                                fn.memsize += int64(len(cando))
                                ptr.repacked++
                                fn.repacked++
                        } else {
-                               // Insert an extent between prev and cur, and advance prev/cur.
-                               fn.extents = append(fn.extents, nil)
-                               if cur < len(fn.extents) {
-                                       copy(fn.extents[cur+1:], fn.extents[cur:])
+                               // Insert a segment between prev and
+                               // cur, and advance prev/cur.
+                               fn.segments = append(fn.segments, nil)
+                               if cur < len(fn.segments) {
+                                       copy(fn.segments[cur+1:], fn.segments[cur:])
                                        ptr.repacked++
                                        fn.repacked++
                                } else {
-                                       // appending a new extent does
+                                       // appending a new segment does
                                        // not invalidate any ptrs
                                }
-                               e := &memExtent{}
-                               e.Truncate(len(cando))
+                               seg := &memSegment{}
+                               seg.Truncate(len(cando))
                                fn.memsize += int64(len(cando))
-                               fn.extents[cur] = e
+                               fn.segments[cur] = seg
                                cur++
                                prev++
                        }
                }
 
-               // Finally we can copy bytes from cando to the current extent.
-               fn.extents[ptr.extentIdx].(writableExtent).WriteAt(cando, ptr.extentOff)
+               // Finally we can copy bytes from cando to the current segment.
+               fn.segments[ptr.segmentIdx].(*memSegment).WriteAt(cando, ptr.segmentOff)
                n += len(cando)
                p = p[len(cando):]
 
                ptr.off += int64(len(cando))
-               ptr.extentOff += len(cando)
-               if ptr.extentOff >= maxBlockSize {
-                       fn.pruneMemExtents()
+               ptr.segmentOff += len(cando)
+               if ptr.segmentOff >= maxBlockSize {
+                       fn.pruneMemSegments()
                }
-               if fn.extents[ptr.extentIdx].Len() == ptr.extentOff {
-                       ptr.extentOff = 0
-                       ptr.extentIdx++
+               if fn.segments[ptr.segmentIdx].Len() == ptr.segmentOff {
+                       ptr.segmentOff = 0
+                       ptr.segmentIdx++
                }
+
+               fn.fileinfo.modTime = time.Now()
        }
        return
 }
 
 // Write some data out to disk to reduce memory use. Caller must have
 // write lock.
-func (fn *filenode) pruneMemExtents() {
+func (fn *filenode) pruneMemSegments() {
        // TODO: async (don't hold Lock() while waiting for Keep)
        // TODO: share code with (*dirnode)sync()
        // TODO: pack/flush small blocks too, when fragmented
-       for idx, ext := range fn.extents {
-               ext, ok := ext.(*memExtent)
-               if !ok || ext.Len() < maxBlockSize {
+       for idx, seg := range fn.segments {
+               seg, ok := seg.(*memSegment)
+               if !ok || seg.Len() < maxBlockSize {
                        continue
                }
-               locator, _, err := fn.parent.kc.PutB(ext.buf)
+               locator, _, err := fn.parent.kc.PutB(seg.buf)
                if err != nil {
                        // TODO: stall (or return errors from)
                        // subsequent writes until flushing
                        // starts to succeed
                        continue
                }
-               fn.memsize -= int64(ext.Len())
-               fn.extents[idx] = storedExtent{
+               fn.memsize -= int64(seg.Len())
+               fn.segments[idx] = storedSegment{
                        kc:      fn.parent.kc,
                        locator: locator,
-                       size:    ext.Len(),
+                       size:    seg.Len(),
                        offset:  0,
-                       length:  ext.Len(),
+                       length:  seg.Len(),
                }
        }
 }
 
 // FileSystem returns a CollectionFileSystem for the collection.
 func (c *Collection) FileSystem(client *Client, kc keepClient) (CollectionFileSystem, error) {
+       var modTime time.Time
+       if c.ModifiedAt == nil {
+               modTime = time.Now()
+       } else {
+               modTime = *c.ModifiedAt
+       }
        fs := &fileSystem{dirnode: dirnode{
-               client:   client,
-               kc:       kc,
-               fileinfo: fileinfo{name: ".", mode: os.ModeDir | 0755},
-               parent:   nil,
-               inodes:   make(map[string]inode),
+               client: client,
+               kc:     kc,
+               fileinfo: fileinfo{
+                       name:    ".",
+                       mode:    os.ModeDir | 0755,
+                       modTime: modTime,
+               },
+               parent: nil,
+               inodes: make(map[string]inode),
        }}
        fs.dirnode.parent = &fs.dirnode
        if err := fs.dirnode.loadManifest(c.ManifestText); err != nil {
@@ -515,7 +557,7 @@ func (c *Collection) FileSystem(client *Client, kc keepClient) (CollectionFileSy
        return fs, nil
 }
 
-type file struct {
+type filehandle struct {
        inode
        ptr        filenodePtr
        append     bool
@@ -524,7 +566,7 @@ type file struct {
        unreaddirs []os.FileInfo
 }
 
-func (f *file) Read(p []byte) (n int, err error) {
+func (f *filehandle) Read(p []byte) (n int, err error) {
        if !f.readable {
                return 0, ErrWriteOnlyMode
        }
@@ -534,23 +576,20 @@ func (f *file) Read(p []byte) (n int, err error) {
        return
 }
 
-func (f *file) Seek(off int64, whence int) (pos int64, err error) {
+func (f *filehandle) Seek(off int64, whence int) (pos int64, err error) {
        size := f.inode.Size()
        ptr := f.ptr
        switch whence {
-       case os.SEEK_SET:
+       case io.SeekStart:
                ptr.off = off
-       case os.SEEK_CUR:
+       case io.SeekCurrent:
                ptr.off += off
-       case os.SEEK_END:
+       case io.SeekEnd:
                ptr.off = size + off
        }
        if ptr.off < 0 {
                return f.ptr.off, ErrNegativeOffset
        }
-       if ptr.off > size {
-               ptr.off = size
-       }
        if ptr.off != f.ptr.off {
                f.ptr = ptr
                // force filenode to recompute f.ptr fields on next
@@ -560,11 +599,11 @@ func (f *file) Seek(off int64, whence int) (pos int64, err error) {
        return f.ptr.off, nil
 }
 
-func (f *file) Truncate(size int64) error {
+func (f *filehandle) Truncate(size int64) error {
        return f.inode.Truncate(size)
 }
 
-func (f *file) Write(p []byte) (n int, err error) {
+func (f *filehandle) Write(p []byte) (n int, err error) {
        if !f.writable {
                return 0, ErrReadOnlyFile
        }
@@ -572,17 +611,17 @@ func (f *file) Write(p []byte) (n int, err error) {
        defer f.inode.Unlock()
        if fn, ok := f.inode.(*filenode); ok && f.append {
                f.ptr = filenodePtr{
-                       off:       fn.fileinfo.size,
-                       extentIdx: len(fn.extents),
-                       extentOff: 0,
-                       repacked:  fn.repacked,
+                       off:        fn.fileinfo.size,
+                       segmentIdx: len(fn.segments),
+                       segmentOff: 0,
+                       repacked:   fn.repacked,
                }
        }
        n, f.ptr, err = f.inode.Write(p, f.ptr)
        return
 }
 
-func (f *file) Readdir(count int) ([]os.FileInfo, error) {
+func (f *filehandle) Readdir(count int) ([]os.FileInfo, error) {
        if !f.inode.Stat().IsDir() {
                return nil, ErrInvalidOperation
        }
@@ -603,12 +642,11 @@ func (f *file) Readdir(count int) ([]os.FileInfo, error) {
        return ret, nil
 }
 
-func (f *file) Stat() (os.FileInfo, error) {
+func (f *filehandle) Stat() (os.FileInfo, error) {
        return f.inode.Stat(), nil
 }
 
-func (f *file) Close() error {
-       // FIXME: flush
+func (f *filehandle) Close() error {
        return nil
 }
 
@@ -637,7 +675,7 @@ func (dn *dirnode) sync() error {
                }
                block := make([]byte, 0, maxBlockSize)
                for _, sb := range sbs {
-                       block = append(block, sb.fn.extents[sb.idx].(*memExtent).buf...)
+                       block = append(block, sb.fn.segments[sb.idx].(*memSegment).buf...)
                }
                locator, _, err := dn.kc.PutB(block)
                if err != nil {
@@ -645,8 +683,8 @@ func (dn *dirnode) sync() error {
                }
                off := 0
                for _, sb := range sbs {
-                       data := sb.fn.extents[sb.idx].(*memExtent).buf
-                       sb.fn.extents[sb.idx] = storedExtent{
+                       data := sb.fn.segments[sb.idx].(*memSegment).buf
+                       sb.fn.segments[sb.idx] = storedSegment{
                                kc:      dn.kc,
                                locator: locator,
                                size:    len(block),
@@ -672,18 +710,18 @@ func (dn *dirnode) sync() error {
                }
                fn.Lock()
                defer fn.Unlock()
-               for idx, ext := range fn.extents {
-                       ext, ok := ext.(*memExtent)
+               for idx, seg := range fn.segments {
+                       seg, ok := seg.(*memSegment)
                        if !ok {
                                continue
                        }
-                       if ext.Len() > maxBlockSize/2 {
+                       if seg.Len() > maxBlockSize/2 {
                                if err := flush([]shortBlock{{fn, idx}}); err != nil {
                                        return err
                                }
                                continue
                        }
-                       if pendingLen+ext.Len() > maxBlockSize {
+                       if pendingLen+seg.Len() > maxBlockSize {
                                if err := flush(pending); err != nil {
                                        return err
                                }
@@ -691,7 +729,7 @@ func (dn *dirnode) sync() error {
                                pendingLen = 0
                        }
                        pending = append(pending, shortBlock{fn, idx})
-                       pendingLen += ext.Len()
+                       pendingLen += seg.Len()
                }
        }
        return flush(pending)
@@ -706,12 +744,12 @@ func (dn *dirnode) MarshalManifest(prefix string) (string, error) {
 // caller must have read lock.
 func (dn *dirnode) marshalManifest(prefix string) (string, error) {
        var streamLen int64
-       type m1segment struct {
+       type filepart struct {
                name   string
                offset int64
                length int64
        }
-       var segments []m1segment
+       var fileparts []filepart
        var subdirs string
        var blocks []string
 
@@ -728,8 +766,7 @@ func (dn *dirnode) marshalManifest(prefix string) (string, error) {
        sort.Strings(names)
 
        for _, name := range names {
-               node := dn.inodes[name]
-               switch node := node.(type) {
+               switch node := dn.inodes[name].(type) {
                case *dirnode:
                        subdir, err := node.marshalManifest(prefix + "/" + name)
                        if err != nil {
@@ -737,36 +774,36 @@ func (dn *dirnode) marshalManifest(prefix string) (string, error) {
                        }
                        subdirs = subdirs + subdir
                case *filenode:
-                       if len(node.extents) == 0 {
-                               segments = append(segments, m1segment{name: name})
+                       if len(node.segments) == 0 {
+                               fileparts = append(fileparts, filepart{name: name})
                                break
                        }
-                       for _, e := range node.extents {
-                               switch e := e.(type) {
-                               case storedExtent:
-                                       if len(blocks) > 0 && blocks[len(blocks)-1] == e.locator {
-                                               streamLen -= int64(e.size)
+                       for _, seg := range node.segments {
+                               switch seg := seg.(type) {
+                               case storedSegment:
+                                       if len(blocks) > 0 && blocks[len(blocks)-1] == seg.locator {
+                                               streamLen -= int64(seg.size)
                                        } else {
-                                               blocks = append(blocks, e.locator)
+                                               blocks = append(blocks, seg.locator)
                                        }
-                                       next := m1segment{
+                                       next := filepart{
                                                name:   name,
-                                               offset: streamLen + int64(e.offset),
-                                               length: int64(e.length),
+                                               offset: streamLen + int64(seg.offset),
+                                               length: int64(seg.length),
                                        }
-                                       if prev := len(segments) - 1; prev >= 0 &&
-                                               segments[prev].name == name &&
-                                               segments[prev].offset+segments[prev].length == next.offset {
-                                               segments[prev].length += next.length
+                                       if prev := len(fileparts) - 1; prev >= 0 &&
+                                               fileparts[prev].name == name &&
+                                               fileparts[prev].offset+fileparts[prev].length == next.offset {
+                                               fileparts[prev].length += next.length
                                        } else {
-                                               segments = append(segments, next)
+                                               fileparts = append(fileparts, next)
                                        }
-                                       streamLen += int64(e.size)
+                                       streamLen += int64(seg.size)
                                default:
                                        // This can't happen: we
                                        // haven't unlocked since
                                        // calling sync().
-                                       panic(fmt.Sprintf("can't marshal extent type %T", e))
+                                       panic(fmt.Sprintf("can't marshal segment type %T", seg))
                                }
                        }
                default:
@@ -774,7 +811,7 @@ func (dn *dirnode) marshalManifest(prefix string) (string, error) {
                }
        }
        var filetokens []string
-       for _, s := range segments {
+       for _, s := range fileparts {
                filetokens = append(filetokens, fmt.Sprintf("%d:%d:%s", s.offset, s.length, manifestEscape(s.name)))
        }
        if len(filetokens) == 0 {
@@ -786,16 +823,19 @@ func (dn *dirnode) marshalManifest(prefix string) (string, error) {
 }
 
 func (dn *dirnode) loadManifest(txt string) error {
-       // FIXME: faster
        var dirname string
        streams := strings.Split(txt, "\n")
        if streams[len(streams)-1] != "" {
                return fmt.Errorf("line %d: no trailing newline", len(streams))
        }
-       for i, stream := range streams[:len(streams)-1] {
+       streams = streams[:len(streams)-1]
+       segments := []storedSegment{}
+       for i, stream := range streams {
                lineno := i + 1
-               var extents []storedExtent
                var anyFileTokens bool
+               var pos int64
+               var segIdx int
+               segments = segments[:0]
                for i, token := range strings.Split(stream, " ") {
                        if i == 0 {
                                dirname = manifestUnescape(token)
@@ -813,18 +853,18 @@ func (dn *dirnode) loadManifest(txt string) error {
                                if err != nil || length < 0 {
                                        return fmt.Errorf("line %d: bad locator %q", lineno, token)
                                }
-                               extents = append(extents, storedExtent{
+                               segments = append(segments, storedSegment{
                                        locator: token,
                                        size:    int(length),
                                        offset:  0,
                                        length:  int(length),
                                })
                                continue
-                       } else if len(extents) == 0 {
+                       } else if len(segments) == 0 {
                                return fmt.Errorf("line %d: bad locator %q", lineno, token)
                        }
 
-                       toks := strings.Split(token, ":")
+                       toks := strings.SplitN(token, ":", 3)
                        if len(toks) != 3 {
                                return fmt.Errorf("line %d: bad file segment %q", lineno, token)
                        }
@@ -838,57 +878,59 @@ func (dn *dirnode) loadManifest(txt string) error {
                        if err != nil || length < 0 {
                                return fmt.Errorf("line %d: bad file segment %q", lineno, token)
                        }
-                       name := path.Clean(dirname + "/" + manifestUnescape(toks[2]))
-                       err = dn.makeParentDirs(name)
+                       name := dirname + "/" + manifestUnescape(toks[2])
+                       fnode, err := dn.createFileAndParents(name)
                        if err != nil {
                                return fmt.Errorf("line %d: cannot use path %q: %s", lineno, name, err)
                        }
-                       f, err := dn.OpenFile(name, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0700)
-                       if err != nil {
-                               return fmt.Errorf("line %d: cannot append to %q: %s", lineno, name, err)
-                       }
-                       if f.inode.Stat().IsDir() {
-                               f.Close()
-                               return fmt.Errorf("line %d: cannot append to %q: is a directory", lineno, name)
-                       }
                        // Map the stream offset/range coordinates to
                        // block/offset/range coordinates and add
-                       // corresponding storedExtents to the filenode
-                       var pos int64
-                       for _, e := range extents {
-                               next := pos + int64(e.Len())
-                               if next < offset {
+                       // corresponding storedSegments to the filenode
+                       if pos > offset {
+                               // Can't continue where we left off.
+                               // TODO: binary search instead of
+                               // rewinding all the way (but this
+                               // situation might be rare anyway)
+                               segIdx, pos = 0, 0
+                       }
+                       for next := int64(0); segIdx < len(segments); segIdx++ {
+                               seg := segments[segIdx]
+                               next = pos + int64(seg.Len())
+                               if next <= offset || seg.Len() == 0 {
                                        pos = next
                                        continue
                                }
-                               if pos > offset+length {
+                               if pos >= offset+length {
                                        break
                                }
                                var blkOff int
                                if pos < offset {
                                        blkOff = int(offset - pos)
                                }
-                               blkLen := e.Len() - blkOff
+                               blkLen := seg.Len() - blkOff
                                if pos+int64(blkOff+blkLen) > offset+length {
                                        blkLen = int(offset + length - pos - int64(blkOff))
                                }
-                               f.inode.(*filenode).appendExtent(storedExtent{
+                               fnode.appendSegment(storedSegment{
                                        kc:      dn.kc,
-                                       locator: e.locator,
-                                       size:    e.size,
+                                       locator: seg.locator,
+                                       size:    seg.size,
                                        offset:  blkOff,
                                        length:  blkLen,
                                })
-                               pos = next
+                               if next > offset+length {
+                                       break
+                               } else {
+                                       pos = next
+                               }
                        }
-                       f.Close()
-                       if pos < offset+length {
+                       if segIdx == len(segments) && pos < offset+length {
                                return fmt.Errorf("line %d: invalid segment in %d-byte stream: %q", lineno, pos, token)
                        }
                }
                if !anyFileTokens {
                        return fmt.Errorf("line %d: no file segments", lineno)
-               } else if len(extents) == 0 {
+               } else if len(segments) == 0 {
                        return fmt.Errorf("line %d: no locators", lineno)
                } else if dirname == "" {
                        return fmt.Errorf("line %d: no stream name", lineno)
@@ -897,24 +939,43 @@ func (dn *dirnode) loadManifest(txt string) error {
        return nil
 }
 
-func (dn *dirnode) makeParentDirs(name string) (err error) {
-       names := strings.Split(name, "/")
+// only safe to call from loadManifest -- no locking
+func (dn *dirnode) createFileAndParents(path string) (fn *filenode, err error) {
+       names := strings.Split(path, "/")
+       basename := names[len(names)-1]
+       if basename == "" || basename == "." || basename == ".." {
+               err = fmt.Errorf("invalid filename")
+               return
+       }
        for _, name := range names[:len(names)-1] {
-               f, err := dn.OpenFile(name, os.O_CREATE, os.ModeDir|0755)
-               if err != nil {
-                       return err
-               }
-               defer f.Close()
-               var ok bool
-               dn, ok = f.inode.(*dirnode)
-               if !ok {
-                       return ErrFileExists
+               switch name {
+               case "", ".":
+               case "..":
+                       dn = dn.parent
+               default:
+                       switch node := dn.inodes[name].(type) {
+                       case nil:
+                               dn = dn.newDirnode(name, 0755, dn.fileinfo.modTime)
+                       case *dirnode:
+                               dn = node
+                       case *filenode:
+                               err = ErrFileExists
+                               return
+                       }
                }
        }
-       return nil
+       switch node := dn.inodes[basename].(type) {
+       case nil:
+               fn = dn.newFilenode(basename, 0755, dn.fileinfo.modTime)
+       case *filenode:
+               fn = node
+       case *dirnode:
+               err = ErrIsDirectory
+       }
+       return
 }
 
-func (dn *dirnode) mkdir(name string) (*file, error) {
+func (dn *dirnode) mkdir(name string) (*filehandle, error) {
        return dn.OpenFile(name, os.O_CREATE|os.O_EXCL, os.ModeDir|0755)
 }
 
@@ -927,11 +988,17 @@ func (dn *dirnode) Mkdir(name string, perm os.FileMode) error {
 }
 
 func (dn *dirnode) Remove(name string) error {
-       return dn.remove(name, false)
+       return dn.remove(strings.TrimRight(name, "/"), false)
 }
 
 func (dn *dirnode) RemoveAll(name string) error {
-       return dn.remove(name, true)
+       err := dn.remove(strings.TrimRight(name, "/"), true)
+       if os.IsNotExist(err) {
+               // "If the path does not exist, RemoveAll returns
+               // nil." (see "os" pkg)
+               err = nil
+       }
+       return err
 }
 
 func (dn *dirnode) remove(name string, recursive bool) error {
@@ -988,7 +1055,7 @@ func (dn *dirnode) Rename(oldname, newname string) error {
        // newdir, then locking the path from root to olddir, skipping
        // any already-locked nodes.
        needLock := []sync.Locker{}
-       for _, f := range []*file{olddirf, newdirf} {
+       for _, f := range []*filehandle{olddirf, newdirf} {
                node := f.inode
                needLock = append(needLock, node)
                for node.Parent() != node {
@@ -1011,6 +1078,10 @@ func (dn *dirnode) Rename(oldname, newname string) error {
        if !ok {
                return os.ErrNotExist
        }
+       if locked[oldinode] {
+               // oldinode cannot become a descendant of itself.
+               return ErrInvalidArgument
+       }
        if existing, ok := newdn.inodes[newname]; ok {
                // overwriting an existing file or dir
                if dn, ok := existing.(*dirnode); ok {
@@ -1024,9 +1095,20 @@ func (dn *dirnode) Rename(oldname, newname string) error {
                        }
                }
        } else {
+               if newdn.inodes == nil {
+                       newdn.inodes = make(map[string]inode)
+               }
                newdn.fileinfo.size++
        }
        newdn.inodes[newname] = oldinode
+       switch n := oldinode.(type) {
+       case *dirnode:
+               n.parent = newdn
+       case *filenode:
+               n.parent = newdn
+       default:
+               panic(fmt.Sprintf("bad inode type %T", n))
+       }
        delete(olddn.inodes, oldname)
        olddn.fileinfo.size--
        return nil
@@ -1096,8 +1178,44 @@ func (dn *dirnode) lookupPath(path string) (node inode) {
        return
 }
 
+func (dn *dirnode) newDirnode(name string, perm os.FileMode, modTime time.Time) *dirnode {
+       child := &dirnode{
+               parent: dn,
+               client: dn.client,
+               kc:     dn.kc,
+               fileinfo: fileinfo{
+                       name:    name,
+                       mode:    os.ModeDir | perm,
+                       modTime: modTime,
+               },
+       }
+       if dn.inodes == nil {
+               dn.inodes = make(map[string]inode)
+       }
+       dn.inodes[name] = child
+       dn.fileinfo.size++
+       return child
+}
+
+func (dn *dirnode) newFilenode(name string, perm os.FileMode, modTime time.Time) *filenode {
+       child := &filenode{
+               parent: dn,
+               fileinfo: fileinfo{
+                       name:    name,
+                       mode:    perm,
+                       modTime: modTime,
+               },
+       }
+       if dn.inodes == nil {
+               dn.inodes = make(map[string]inode)
+       }
+       dn.inodes[name] = child
+       dn.fileinfo.size++
+       return child
+}
+
 // OpenFile is analogous to os.OpenFile().
-func (dn *dirnode) OpenFile(name string, flag int, perm os.FileMode) (*file, error) {
+func (dn *dirnode) OpenFile(name string, flag int, perm os.FileMode) (*filehandle, error) {
        if flag&os.O_SYNC != 0 {
                return nil, ErrSyncNotSupported
        }
@@ -1123,9 +1241,9 @@ func (dn *dirnode) OpenFile(name string, flag int, perm os.FileMode) (*file, err
                // "foo/..".
                switch name {
                case ".", "":
-                       return &file{inode: dn}, nil
+                       return &filehandle{inode: dn}, nil
                case "..":
-                       return &file{inode: dn.Parent()}, nil
+                       return &filehandle{inode: dn.Parent()}, nil
                }
        }
        createMode := flag&os.O_CREATE != 0
@@ -1142,29 +1260,10 @@ func (dn *dirnode) OpenFile(name string, flag int, perm os.FileMode) (*file, err
                        return nil, os.ErrNotExist
                }
                if perm.IsDir() {
-                       n = &dirnode{
-                               parent: dn,
-                               client: dn.client,
-                               kc:     dn.kc,
-                               fileinfo: fileinfo{
-                                       name: name,
-                                       mode: os.ModeDir | 0755,
-                               },
-                       }
+                       n = dn.newDirnode(name, 0755, time.Now())
                } else {
-                       n = &filenode{
-                               parent: dn,
-                               fileinfo: fileinfo{
-                                       name: name,
-                                       mode: 0755,
-                               },
-                       }
-               }
-               if dn.inodes == nil {
-                       dn.inodes = make(map[string]inode)
+                       n = dn.newFilenode(name, 0755, time.Now())
                }
-               dn.inodes[name] = n
-               dn.fileinfo.size++
        } else if flag&os.O_EXCL != 0 {
                return nil, ErrFileExists
        } else if flag&os.O_TRUNC != 0 {
@@ -1176,7 +1275,7 @@ func (dn *dirnode) OpenFile(name string, flag int, perm os.FileMode) (*file, err
                        fn.Truncate(0)
                }
        }
-       return &file{
+       return &filehandle{
                inode:    n,
                append:   flag&os.O_APPEND != 0,
                readable: readable,
@@ -1184,38 +1283,32 @@ func (dn *dirnode) OpenFile(name string, flag int, perm os.FileMode) (*file, err
        }, nil
 }
 
-type extent interface {
+type segment interface {
        io.ReaderAt
        Len() int
-       // Return a new extent with a subsection of the data from this
+       // Return a new segment with a subsection of the data from this
        // one. length<0 means length=Len()-off.
-       Slice(off int, length int) extent
-}
-
-type writableExtent interface {
-       extent
-       WriteAt(p []byte, off int)
-       Truncate(n int)
+       Slice(off int, length int) segment
 }
 
-type memExtent struct {
+type memSegment struct {
        buf []byte
 }
 
-func (me *memExtent) Len() int {
+func (me *memSegment) Len() int {
        return len(me.buf)
 }
 
-func (me *memExtent) Slice(off, length int) extent {
+func (me *memSegment) Slice(off, length int) segment {
        if length < 0 {
                length = len(me.buf) - off
        }
        buf := make([]byte, length)
        copy(buf, me.buf[off:])
-       return &memExtent{buf: buf}
+       return &memSegment{buf: buf}
 }
 
-func (me *memExtent) Truncate(n int) {
+func (me *memSegment) Truncate(n int) {
        if n > cap(me.buf) {
                newsize := 1024
                for newsize < n {
@@ -1234,14 +1327,14 @@ func (me *memExtent) Truncate(n int) {
        me.buf = me.buf[:n]
 }
 
-func (me *memExtent) WriteAt(p []byte, off int) {
+func (me *memSegment) WriteAt(p []byte, off int) {
        if off+len(p) > len(me.buf) {
-               panic("overflowed extent")
+               panic("overflowed segment")
        }
        copy(me.buf[off:], p)
 }
 
-func (me *memExtent) ReadAt(p []byte, off int64) (n int, err error) {
+func (me *memSegment) ReadAt(p []byte, off int64) (n int, err error) {
        if off > int64(me.Len()) {
                err = io.EOF
                return
@@ -1253,19 +1346,19 @@ func (me *memExtent) ReadAt(p []byte, off int64) (n int, err error) {
        return
 }
 
-type storedExtent struct {
+type storedSegment struct {
        kc      keepClient
        locator string
-       size    int
-       offset  int
-       length  int
+       size    int // size of stored block (also encoded in locator)
+       offset  int // position of segment within the stored block
+       length  int // bytes in this segment (offset + length <= size)
 }
 
-func (se storedExtent) Len() int {
+func (se storedSegment) Len() int {
        return se.length
 }
 
-func (se storedExtent) Slice(n, size int) extent {
+func (se storedSegment) Slice(n, size int) segment {
        se.offset += n
        se.length -= n
        if size >= 0 && se.length > size {
@@ -1274,7 +1367,7 @@ func (se storedExtent) Slice(n, size int) extent {
        return se
 }
 
-func (se storedExtent) ReadAt(p []byte, off int64) (n int, err error) {
+func (se storedSegment) ReadAt(p []byte, off int64) (n int, err error) {
        if off > int64(se.length) {
                return 0, io.EOF
        }
@@ -1300,7 +1393,7 @@ func canonicalName(name string) string {
        return name
 }
 
-var manifestEscapeSeq = regexp.MustCompile(`\\([0-9]{3}|\\)`)
+var manifestEscapeSeq = regexp.MustCompile(`\\([0-7]{3}|\\)`)
 
 func manifestUnescapeFunc(seq string) string {
        if seq == `\\` {
@@ -1318,7 +1411,7 @@ func manifestUnescape(s string) string {
        return manifestEscapeSeq.ReplaceAllStringFunc(s, manifestUnescapeFunc)
 }
 
-var manifestEscapedChar = regexp.MustCompile(`[^\.\w/]`)
+var manifestEscapedChar = regexp.MustCompile(`[\000-\040:\s\\]`)
 
 func manifestEscapeFunc(seq string) string {
        return fmt.Sprintf("\\%03o", byte(seq[0]))