On Wed, Jan 23, 2013 at 1:04 PM, Chen Yang <chenyang.fnst@xxxxxxxxxxxxxx> wrote:
> From: Chen Yang <chenyang.fnst@xxxxxxxxxxxxxx>
> Date: Fri, 18 Jan 2013 14:54:31 +0800
> Subject: [PATCH] Btrfs-progs/receive: sparse and pre-allocated file support
> for btrfs-send mechanism
>
> When sending a file with sparse or pre-allocated part,
> these parts will be sent as ZERO streams, and it's unnecessary.
>
> To improve this, we add a punch command on the sending side, so the
> receiving side changed with it. The main change is adding the punch
> processing to receive command.
>
> Signed-off-by: Cheng Yang <chenyang.fnst@xxxxxxxxxxxxxx>
> ---
> cmds-receive.c | 27 +++++++++++++++++++++++++++
> send-stream.c | 6 ++++++
> send-stream.h | 1 +
> send.h | 3 ++-
> 4 files changed, 36 insertions(+), 1 deletions(-)
>
> diff --git a/cmds-receive.c b/cmds-receive.c
> index a8be6fa..74cbfc4 100644
> --- a/cmds-receive.c
> +++ b/cmds-receive.c
> @@ -37,6 +37,7 @@
> #include <sys/types.h>
> #include <sys/xattr.h>
> #include <uuid/uuid.h>
> +#include <linux/falloc.h>
>
> #include "ctree.h"
> #include "ioctl.h"
> @@ -508,6 +509,31 @@ out:
> return ret;
> }
>
> +static int process_punch(const char *path, u64 offset, u64 len, void *user)
> +{
> + int ret = 0;
> + struct btrfs_receive *r = user;
> + char *full_path = path_cat(r->full_subvol_path, path);
> +
> + ret = open_inode_for_write(r, full_path);
> + if (ret < 0)
> + goto out;
> +
> + ret = fallocate(r->write_fd,
> + FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
> + offset, len);
> + if (ret < 0) {
> + ret = -errno;
> + fprintf(stderr, "ERROR: punch %s failed. %s\n",
> + path, strerror(-ret));
> + goto out;
> + }
> +
> +out:
> + free(full_path);
> + return ret;
> +}
> +
> static int process_write(const char *path, const void *data, u64 offset,
> u64 len, void *user)
> {
> @@ -777,6 +803,7 @@ struct btrfs_send_ops send_ops = {
> .link = process_link,
> .unlink = process_unlink,
> .rmdir = process_rmdir,
> + .punch = process_punch,
> .write = process_write,
> .clone = process_clone,
> .set_xattr = process_set_xattr,
> diff --git a/send-stream.c b/send-stream.c
> index 55fa728..9f3ede7 100644
> --- a/send-stream.c
> +++ b/send-stream.c
> @@ -362,6 +362,12 @@ static int read_and_process_cmd(struct btrfs_send_stream *s)
> TLV_GET_STRING(s, BTRFS_SEND_A_PATH, &path);
> ret = s->ops->rmdir(path, s->user);
> break;
> + case BTRFS_SEND_C_PUNCH:
> + TLV_GET_STRING(s, BTRFS_SEND_A_PATH, &path);
> + TLV_GET_U64(s, BTRFS_SEND_A_FILE_OFFSET, &offset);
> + TLV_GET_U64(s, BTRFS_SEND_A_SIZE, &len);
> + ret = s->ops->punch(path, offset, len, s->user);
> + break;
> case BTRFS_SEND_C_WRITE:
> TLV_GET_STRING(s, BTRFS_SEND_A_PATH, &path);
> TLV_GET_U64(s, BTRFS_SEND_A_FILE_OFFSET, &offset);
> diff --git a/send-stream.h b/send-stream.h
> index b69b7f1..f83f2ac 100644
> --- a/send-stream.h
> +++ b/send-stream.h
> @@ -34,6 +34,7 @@ struct btrfs_send_ops {
> int (*link)(const char *path, const char *lnk, void *user);
> int (*unlink)(const char *path, void *user);
> int (*rmdir)(const char *path, void *user);
> + int (*punch)(const char *path, u64 offset, u64 len, void *user);
> int (*write)(const char *path, const void *data, u64 offset, u64 len,
> void *user);
> int (*clone)(const char *path, u64 offset, u64 len,
> diff --git a/send.h b/send.h
> index 9934e94..10a88d2 100644
> --- a/send.h
> +++ b/send.h
> @@ -20,7 +20,7 @@
> #include "ctree.h"
>
> #define BTRFS_SEND_STREAM_MAGIC "btrfs-stream"
> -#define BTRFS_SEND_STREAM_VERSION 1
> +#define BTRFS_SEND_STREAM_VERSION 2
>
> #define BTRFS_SEND_BUF_SIZE (1024 * 64)
> #define BTRFS_SEND_READ_SIZE (1024 * 48)
> @@ -80,6 +80,7 @@ enum btrfs_send_cmd {
> BTRFS_SEND_C_WRITE,
> BTRFS_SEND_C_CLONE,
>
> + BTRFS_SEND_C_PUNCH,
> BTRFS_SEND_C_TRUNCATE,
> BTRFS_SEND_C_CHMOD,
> BTRFS_SEND_C_CHOWN,
I think this breaks the current protocol, because it changes the
numbers for existing commands, starting from BTRFS_SEND_C_TRUNCATE. I
don't think this will be acceptable for existing users.
I think the new commands should be added after BTRFS_SEND_C_END
command (unfortunately), like the snapper command that was added
recently.
Thanks,
Alex.
> --
> 1.7.7.6
>
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