-----Original Message----- From: Jรกn Tomko [mailto:jtomko@redhat.com] Sent: Friday, January 16, 2015 10:22 PM To: Chen, Hanxiao/้ ๆ้; libvir-list@redhat.com Subject: Re: [libvirt] [PATCH 2/2] storage: try to perform btrfs COW copy if possible
On 01/13/2015 09:18 AM, Chen Hanxiao wrote:
We don't take advantage of clone of btrfs.
So a)try to do a btrfs lightweight copy
b)fall back to a standard copy if COW copy not supported.
Signed-off-by: Chen Hanxiao <chenhanxiao@cn.fujitsu.com> --- include/libvirt/libvirt-storage.h | 1 + src/storage/storage_backend.c | 39 ++++++++++++++++++++++++++++++++------- src/storage/storage_backend_fs.c | 8 ++++++-- src/storage/storage_driver.c | 4 +++- 4 files changed, 42 insertions(+), 10 deletions(-)
diff --git a/include/libvirt/libvirt-storage.h b/include/libvirt/libvirt-storage.h index 1f3087b..4ae42e1 100644 --- a/include/libvirt/libvirt-storage.h +++ b/include/libvirt/libvirt-storage.h @@ -306,6 +306,7 @@ const char* virStorageVolGetKey (virStorageVolPtr vol);
typedef enum { VIR_STORAGE_VOL_CREATE_PREALLOC_METADATA = 1 << 0, + VIR_STORAGE_VOL_CREATE_REFLINK = 1 << 1,
There should be some human-readable commentary after the flag, that will be shown on our API reference page: http://libvirt.org/html/libvirt-libvirt-storage.html#virStorageVolCreateFlag...
Will do.
} virStorageVolCreateFlags;
virStorageVolPtr virStorageVolCreateXML (virStoragePoolPtr pool, diff --git a/src/storage/storage_backend.c b/src/storage/storage_backend.c index 5ce3566..838398e 100644 --- a/src/storage/storage_backend.c +++ b/src/storage/storage_backend.c @@ -187,7 +187,8 @@ virStorageBackendCopyToFD(virStorageVolDefPtr vol, virStorageVolDefPtr inputvol, int fd, unsigned long long *total, - bool want_sparse) + bool want_sparse, + bool reflink_copy) { int inputfd = -1; int amtread = -1; @@ -226,6 +227,15 @@ virStorageBackendCopyToFD(virStorageVolDefPtr vol, goto cleanup; }
+ if (reflink_copy) { + if (btrfsCloneFile(fd, inputfd) == -1) { + VIR_DEBUG("btrfs clone not supported, try another way.");
If reflink copy is unsupported, I think we should just error out, as a full copy won't be as fast / occupy as little space.
Also, this would fall back even on other errors.
That's a better solution, will be changed in v2. Thanks, - Chen
The rest looks good to me.
Jan