diff options
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/handle.go | 41 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/special_file.go | 37 |
2 files changed, 50 insertions, 28 deletions
diff --git a/pkg/sentry/fsimpl/gofer/handle.go b/pkg/sentry/fsimpl/gofer/handle.go index 5c57f6fea..02540a754 100644 --- a/pkg/sentry/fsimpl/gofer/handle.go +++ b/pkg/sentry/fsimpl/gofer/handle.go @@ -20,6 +20,7 @@ import ( "gvisor.dev/gvisor/pkg/p9" "gvisor.dev/gvisor/pkg/safemem" "gvisor.dev/gvisor/pkg/sentry/hostfd" + "gvisor.dev/gvisor/pkg/sync" ) // handle represents a remote "open file descriptor", consisting of an opened @@ -130,3 +131,43 @@ func (h *handle) writeFromBlocksAt(ctx context.Context, srcs safemem.BlockSeq, o } return uint64(n), cperr } + +type handleReadWriter struct { + ctx context.Context + h *handle + off uint64 +} + +var handleReadWriterPool = sync.Pool{ + New: func() interface{} { + return &handleReadWriter{} + }, +} + +func getHandleReadWriter(ctx context.Context, h *handle, offset int64) *handleReadWriter { + rw := handleReadWriterPool.Get().(*handleReadWriter) + rw.ctx = ctx + rw.h = h + rw.off = uint64(offset) + return rw +} + +func putHandleReadWriter(rw *handleReadWriter) { + rw.ctx = nil + rw.h = nil + handleReadWriterPool.Put(rw) +} + +// ReadToBlocks implements safemem.Reader.ReadToBlocks. +func (rw *handleReadWriter) ReadToBlocks(dsts safemem.BlockSeq) (uint64, error) { + n, err := rw.h.readToBlocksAt(rw.ctx, dsts, rw.off) + rw.off += n + return n, err +} + +// WriteFromBlocks implements safemem.Writer.WriteFromBlocks. +func (rw *handleReadWriter) WriteFromBlocks(srcs safemem.BlockSeq) (uint64, error) { + n, err := rw.h.writeFromBlocksAt(rw.ctx, srcs, rw.off) + rw.off += n + return n, err +} diff --git a/pkg/sentry/fsimpl/gofer/special_file.go b/pkg/sentry/fsimpl/gofer/special_file.go index 144a1045e..8e3c41808 100644 --- a/pkg/sentry/fsimpl/gofer/special_file.go +++ b/pkg/sentry/fsimpl/gofer/special_file.go @@ -24,7 +24,6 @@ import ( "gvisor.dev/gvisor/pkg/fdnotifier" "gvisor.dev/gvisor/pkg/metric" "gvisor.dev/gvisor/pkg/p9" - "gvisor.dev/gvisor/pkg/safemem" "gvisor.dev/gvisor/pkg/sentry/fsmetric" "gvisor.dev/gvisor/pkg/sentry/vfs" "gvisor.dev/gvisor/pkg/sync" @@ -229,23 +228,13 @@ func (fd *specialFileFD) PRead(ctx context.Context, dst usermem.IOSequence, offs } } - // Going through dst.CopyOutFrom() would hold MM locks around file - // operations of unknown duration. For regularFileFD, doing so is necessary - // to support mmap due to lock ordering; MM locks precede dentry.dataMu. - // That doesn't hold here since specialFileFD doesn't client-cache data. - // Just buffer the read instead. - buf := make([]byte, dst.NumBytes()) - n, err := fd.handle.readToBlocksAt(ctx, safemem.BlockSeqOf(safemem.BlockFromSafeSlice(buf)), uint64(offset)) + rw := getHandleReadWriter(ctx, &fd.handle, offset) + n, err := dst.CopyOutFrom(ctx, rw) + putHandleReadWriter(rw) if linuxerr.Equals(linuxerr.EAGAIN, err) { err = linuxerr.ErrWouldBlock } - if n == 0 { - return bufN, err - } - if cp, cperr := dst.CopyOut(ctx, buf[:n]); cperr != nil { - return bufN + int64(cp), cperr - } - return bufN + int64(n), err + return bufN + n, err } // Read implements vfs.FileDescriptionImpl.Read. @@ -316,20 +305,15 @@ func (fd *specialFileFD) pwrite(ctx context.Context, src usermem.IOSequence, off } } - // Do a buffered write. See rationale in PRead. - buf := make([]byte, src.NumBytes()) - copied, copyErr := src.CopyIn(ctx, buf) - if copied == 0 && copyErr != nil { - // Only return the error if we didn't get any data. - return 0, offset, copyErr - } - n, err := fd.handle.writeFromBlocksAt(ctx, safemem.BlockSeqOf(safemem.BlockFromSafeSlice(buf[:copied])), uint64(offset)) + rw := getHandleReadWriter(ctx, &fd.handle, offset) + n, err := src.CopyInTo(ctx, rw) + putHandleReadWriter(rw) if linuxerr.Equals(linuxerr.EAGAIN, err) { err = linuxerr.ErrWouldBlock } // Update offset if the offset is valid. if offset >= 0 { - offset += int64(n) + offset += n } // Update file size for regular files. if fd.isRegularFile { @@ -340,10 +324,7 @@ func (fd *specialFileFD) pwrite(ctx context.Context, src usermem.IOSequence, off atomic.StoreUint64(&d.size, uint64(offset)) } } - if err != nil { - return int64(n), offset, err - } - return int64(n), offset, copyErr + return int64(n), offset, err } // Write implements vfs.FileDescriptionImpl.Write. |