On Thu, Jan 24, 2013 at 3:51 AM, Chen Yang <chenyang.fnst@xxxxxxxxxxxxxx> wrote:
>> 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.
>
> yes, I agree with you and I thought it's better to add the command
> after BTRFS_SEND_C_END command. But BTRFS_SEND_C_END seem like more special?
Yes, it's kind of special, but still we cannot change the numbers for
existing commands. If you add a new command, then users with an older
user-space and newer kernel will receive a clear (hopefully) error
about unsupported command. So they can go and upgrade the user-space
tool. (Although looking at the code, they will not receive any error
message, but instead the tool will exit silently returning a non-zero
code. This is also pretty bad.)
If you change the numbers of existing commands, users will start
receiving error messages like "ERROR: attribute 15 requested but not
present", and will need to start figuring out what user-code matches
what kernel-code.
Thanks,
Alex.
>
> Thanks,
> Chen.
>
>>
>> Thanks,
>> Alex.
>>
>>
>>> --
>>> 1.7.7.6
>>>
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