[libvirt] [PATCH 15/8] save: add more iohelper support for O_DIRECT
Daniel P. Berrange
berrange at redhat.com
Tue Jul 19 17:50:13 UTC 2011
On Fri, Jul 15, 2011 at 08:48:18PM -0600, Eric Blake wrote:
> Constraining the problem makes the solution easier to think about.
>
> * src/util/iohelper.c (runIO): Make read support easy.
> ---
>
> Could be squashed into 6/8.
>
> src/util/iohelper.c | 9 ++++++++-
> 1 files changed, 8 insertions(+), 1 deletions(-)
>
> diff --git a/src/util/iohelper.c b/src/util/iohelper.c
> index 82f62e1..f091d13 100644
> --- a/src/util/iohelper.c
> +++ b/src/util/iohelper.c
> @@ -107,6 +107,13 @@ runIO(const char *path, int fd, int oflags, unsigned long long length)
> fdinname = path;
> fdout = STDOUT_FILENO;
> fdoutname = "stdout";
> + /* To make the implementation simpler, we give up on any
> + * attempt to use O_DIRECT in a non-trivial manner. */
> + if (direct && ((end = lseek(fd, 0, SEEK_CUR)) != 0 || length)) {
> + virReportSystemError(end < 0 ? errno : EINVAL, "%s",
> + _("O_DIRECT read needs entire seekable file"));
> + goto cleanup;
> + }
> break;
> case O_WRONLY:
> fdin = STDIN_FILENO;
> @@ -117,7 +124,7 @@ runIO(const char *path, int fd, int oflags, unsigned long long length)
> * attempt to use O_DIRECT in a non-trivial manner. */
> if (direct && (end = lseek(fd, 0, SEEK_END)) != 0) {
> virReportSystemError(end < 0 ? errno : EINVAL, "%s",
> - _("O_DIRECT needs empty seekable file"));
> + _("O_DIRECT write needs empty seekable file"));
> goto cleanup;
> }
> break;
ACK, if this really works for saving guests. We need to skip over the
initial header + XML in save files, so I would have thought we needed
to support a non-empty seekable file.
Daniel
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