Re: [libvirt] [PATCHv2 1/2] storage: introduce btrfsCloneFile() for COW copy
-----Original Message-----
From: Jรกn Tomko [mailto:jtomko@redhat.com]
Sent: Tuesday, January 27, 2015 8:46 PM
To: Chen, Hanxiao/้ ๆ้; libvir-list(a)redhat.com
Subject: Re: [libvirt] [PATCHv2 1/2] storage: introduce btrfsCloneFile() for COW
copy
On 01/23/2015 11:22 AM, Chen Hanxiao wrote:
> Signed-off-by: Chen Hanxiao <chenhanxiao(a)cn.fujitsu.com>
> ---
> configure.ac | 12 ++++++++++++
> src/storage/storage_backend.c | 24 ++++++++++++++++++++++++
> 2 files changed, 36 insertions(+)
>
> diff --git a/configure.ac b/configure.ac
> index f370475..2498389 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -2175,6 +2175,18 @@ fi
> AM_CONDITIONAL([WITH_HYPERV], [test "$with_hyperv" = "yes"])
>
>
> +dnl
> +dnl check for kernel headers required by btrfs ioctl
> +dnl
> +if test "$with_linux" = "yes"; then
> + have_btrfs=no
> + AC_CHECK_HEADER([linux/btrfs.h],[have_btrfs=yes])
> + if test "${have_btrfs}" = yes; then
> + AC_DEFINE([HAVE_BTRFS_IOC_CLONE], 1,
> + [whether have btrfs CoW clone ioctl])
This macro name is misleading (it does not check for clone, just for btrfs.h).
Doing just:
AC_CHECK_HEADERS([linux/btrfs.h])
will define HAVE_LINUX_BTRFS_H
> + fi
> +fi
> +
> dnl Allow perl/python overrides
> AC_PATH_PROGS([PYTHON], [python2 python])
> AC_PATH_PROG([PERL], [perl])
> diff --git a/src/storage/storage_backend.c b/src/storage/storage_backend.c
> index b990a82..d2a664b 100644
> --- a/src/storage/storage_backend.c
> +++ b/src/storage/storage_backend.c
> @@ -46,6 +46,10 @@
> # include <selinux/selinux.h>
> #endif
>
> +#if HAVE_BTRFS_IOC_CLONE
> +# include <linux/btrfs.h>
> +#endif
> +
> #include "datatypes.h"
> #include "virerror.h"
> #include "viralloc.h"
> @@ -156,6 +160,26 @@ enum {
> #define READ_BLOCK_SIZE_DEFAULT (1024 * 1024)
> #define WRITE_BLOCK_SIZE_DEFAULT (4 * 1024)
>
> +/*
> + * Perform the O(1) btrfs clone operation, if possible.
> + * Upon success, return 0. Otherwise, return -1 and set errno.
> + */
> +#if defined(HAVE_BTRFS_IOC_CLONE)
#if HAVE_LINUX_BTRFS_H
> +static inline int
> +btrfsCloneFile(int dest_fd, int src_fd)
> +{
> + return ioctl(dest_fd, BTRFS_IOC_CLONE, src_fd);
> +}
> +#else
> +static inline int
> +btrfsCloneFile(int dest_fd ATTRIBUTE_UNUSED,
> + int src_fd ATTRIBUTE_UNUSED)
> +{
> + errno = ENOTSUP;
> + return -1;
> +}
> +#endif
> +
> static int ATTRIBUTE_NONNULL(2)
> virStorageBackendCopyToFD(virStorageVolDefPtr vol,
> virStorageVolDefPtr inputvol,
>
ACK
I simplified the configure check and pushed the patch.
Thanks for your kindly help.
Regards,
- Chen