/
file.go
244 lines (205 loc) · 4.68 KB
/
file.go
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package fs
import (
"context"
"io"
"log"
"sync"
"syscall"
"bazil.org/bazil/cas/blobs"
wirecas "bazil.org/bazil/cas/wire"
"bazil.org/bazil/db"
"bazil.org/bazil/fs/wire"
"bazil.org/bazil/util/env"
"bazil.org/fuse"
"bazil.org/fuse/fs"
)
type dirtiness int
const (
clean dirtiness = iota
dirty
writing
)
type file struct {
inode uint64
parent *dir
// mu protects the fields below.
mu sync.Mutex
name string
blob *blobs.Blob
dirty dirtiness
handles uint32
// when was this entry last changed
// TODO: written time.Time
}
var _ node = (*file)(nil)
var _ fs.Node = (*file)(nil)
var _ fs.NodeForgetter = (*file)(nil)
var _ fs.NodeOpener = (*file)(nil)
var _ fs.NodeSetattrer = (*file)(nil)
var _ fs.NodeFsyncer = (*file)(nil)
var _ fs.HandleFlusher = (*file)(nil)
var _ fs.HandleReader = (*file)(nil)
var _ fs.HandleWriter = (*file)(nil)
var _ fs.HandleReleaser = (*file)(nil)
func (f *file) setName(name string) {
f.mu.Lock()
defer f.mu.Unlock()
f.name = name
}
func (f *file) marshalInternal(ctx context.Context) (*wire.Dirent, error) {
de := &wire.Dirent{
Inode: f.inode,
}
manifest, err := f.blob.Save(ctx)
if err != nil {
return nil, err
}
de.Type = &wire.Dirent_File{
File: &wire.File{
Manifest: wirecas.FromBlob(manifest),
},
}
return de, nil
}
func (f *file) marshal(ctx context.Context) (*wire.Dirent, error) {
f.mu.Lock()
defer f.mu.Unlock()
return f.marshalInternal(ctx)
}
func (f *file) Attr(ctx context.Context, a *fuse.Attr) error {
f.mu.Lock()
defer f.mu.Unlock()
a.Inode = f.inode
a.Mode = 0644
a.Uid = env.MyUID
a.Gid = env.MyGID
a.Size = f.blob.Size()
return nil
}
func (f *file) Forget() {
f.mu.Lock()
name := f.name
f.mu.Unlock()
f.parent.forgetChild(name, f)
}
func (f *file) Open(ctx context.Context, req *fuse.OpenRequest, resp *fuse.OpenResponse) (fs.Handle, error) {
// allow kernel to use buffer cache
resp.Flags &^= fuse.OpenDirectIO
f.mu.Lock()
defer f.mu.Unlock()
tmp := f.handles + 1
if tmp == 0 {
return nil, fuse.Errno(syscall.ENFILE)
}
f.handles = tmp
return f, nil
}
func (f *file) Write(ctx context.Context, req *fuse.WriteRequest, resp *fuse.WriteResponse) error {
f.mu.Lock()
defer f.mu.Unlock()
f.dirty = dirty
n, err := f.blob.IO(ctx).WriteAt(req.Data, req.Offset)
resp.Size = n
if err != nil {
log.Printf("write error: %v", err)
return fuse.EIO
}
return nil
}
func (f *file) flush(ctx context.Context) error {
f.mu.Lock()
locked := true
defer func() {
if locked {
f.mu.Unlock()
}
}()
// only if dirty
if f.dirty == clean {
return nil
}
f.dirty = writing
de, err := f.marshalInternal(ctx)
if err != nil {
return err
}
f.mu.Unlock()
locked = false
save := func(tx *db.Tx) error {
return f.parent.save(tx, f.name, de)
}
if err := f.parent.fs.db.Update(save); err != nil {
return err
}
f.mu.Lock()
if f.dirty == writing {
// was not dirtied in the meanwhile
f.dirty = clean
}
f.mu.Unlock()
return nil
}
func (f *file) Flush(ctx context.Context, req *fuse.FlushRequest) error {
return f.flush(ctx)
}
const maxInt64 = 9223372036854775807
func (f *file) Read(ctx context.Context, req *fuse.ReadRequest, resp *fuse.ReadResponse) error {
f.mu.Lock()
defer f.mu.Unlock()
if req.Offset < 0 {
panic("unreachable")
}
if req.Offset > maxInt64 {
log.Printf("offset is past int64 max: %d", req.Offset)
return fuse.EIO
}
resp.Data = resp.Data[:req.Size]
n, err := f.blob.IO(ctx).ReadAt(resp.Data, int64(req.Offset))
if err != nil && err != io.EOF {
log.Printf("read error: %v", err)
return fuse.EIO
}
resp.Data = resp.Data[:n]
return nil
}
func (f *file) Setattr(ctx context.Context, req *fuse.SetattrRequest, resp *fuse.SetattrResponse) error {
f.mu.Lock()
defer f.mu.Unlock()
f.dirty = dirty
valid := req.Valid
if valid.Size() {
err := f.blob.Truncate(ctx, req.Size)
if err != nil {
return err
}
valid &^= fuse.SetattrSize
}
// things we don't need to explicitly handle
valid &^= fuse.SetattrLockOwner | fuse.SetattrHandle
if valid != 0 {
// don't let an unhandled operation slip by without error
log.Printf("Setattr did not handle %v", valid)
return fuse.ENOSYS
}
return nil
}
func (f *file) Fsync(ctx context.Context, req *fuse.FsyncRequest) error {
// flush forces writes to backing stores; we don't current
// differentiate between the backing stores writing vs syncing.
return f.flush(ctx)
}
func (f *file) Release(ctx context.Context, req *fuse.ReleaseRequest) error {
// name will be set to filename if this was the last open handle;
// this also neatly ignores deleted files
name := ""
f.mu.Lock()
f.handles--
if f.handles == 0 {
name = f.name
}
f.mu.Unlock()
if name != "" {
f.parent.tryResolveConflicts(name)
}
return nil
}