(Copying Dan in) * Wei Yang (richardw.y...@linux.intel.com) wrote: > In add_to_iovec(), qemu_fflush() will be called if iovec is full. If > this happens, buf_index is reset. Currently, this is not checked and > buf_index would always been adjust with buf size. > > This is not harmful, but will waste some space in file buffer.
That's a nice find. > This patch make add_to_iovec() return 1 when it has flushed the file. > Then the caller could check the return value to see whether it is > necessary to adjust the buf_index any more. > > Signed-off-by: Wei Yang <richardw.y...@linux.intel.com> Reviewed-by: Dr. David Alan Gilbert <dgilb...@redhat.com> (I wonder if there's a way to wrap that little add_to_iovec, check, add to index, flush in a little wrapper). Dave > --- > migration/qemu-file.c | 42 ++++++++++++++++++++++++++++-------------- > 1 file changed, 28 insertions(+), 14 deletions(-) > > diff --git a/migration/qemu-file.c b/migration/qemu-file.c > index 35c22605dd..05d9f42ddb 100644 > --- a/migration/qemu-file.c > +++ b/migration/qemu-file.c > @@ -343,8 +343,16 @@ int qemu_fclose(QEMUFile *f) > return ret; > } > > -static void add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size, > - bool may_free) > +/* > + * Add buf to iovec. Do flush if iovec is full. > + * > + * Return values: > + * 1 iovec is full and flushed > + * 0 iovec is not flushed > + * > + */ > +static int add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size, > + bool may_free) > { > /* check for adjacent buffer and coalesce them */ > if (f->iovcnt > 0 && buf == f->iov[f->iovcnt - 1].iov_base + > @@ -362,7 +370,10 @@ static void add_to_iovec(QEMUFile *f, const uint8_t > *buf, size_t size, > > if (f->iovcnt >= MAX_IOV_SIZE) { > qemu_fflush(f); > + return 1; > } > + > + return 0; > } > > void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, size_t size, > @@ -391,10 +402,11 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, > size_t size) > } > memcpy(f->buf + f->buf_index, buf, l); > f->bytes_xfer += l; > - add_to_iovec(f, f->buf + f->buf_index, l, false); > - f->buf_index += l; > - if (f->buf_index == IO_BUF_SIZE) { > - qemu_fflush(f); > + if (!add_to_iovec(f, f->buf + f->buf_index, l, false)) { > + f->buf_index += l; > + if (f->buf_index == IO_BUF_SIZE) { > + qemu_fflush(f); > + } > } > if (qemu_file_get_error(f)) { > break; > @@ -412,10 +424,11 @@ void qemu_put_byte(QEMUFile *f, int v) > > f->buf[f->buf_index] = v; > f->bytes_xfer++; > - add_to_iovec(f, f->buf + f->buf_index, 1, false); > - f->buf_index++; > - if (f->buf_index == IO_BUF_SIZE) { > - qemu_fflush(f); > + if (!add_to_iovec(f, f->buf + f->buf_index, 1, false)) { > + f->buf_index++; > + if (f->buf_index == IO_BUF_SIZE) { > + qemu_fflush(f); > + } > } > } > > @@ -717,10 +730,11 @@ ssize_t qemu_put_compression_data(QEMUFile *f, z_stream > *stream, > } > > qemu_put_be32(f, blen); > - add_to_iovec(f, f->buf + f->buf_index, blen, false); > - f->buf_index += blen; > - if (f->buf_index == IO_BUF_SIZE) { > - qemu_fflush(f); > + if (!add_to_iovec(f, f->buf + f->buf_index, blen, false)) { > + f->buf_index += blen; > + if (f->buf_index == IO_BUF_SIZE) { > + qemu_fflush(f); > + } > } > return blen + sizeof(int32_t); > } > -- > 2.17.1 > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK