On Thu, Jan 24, 2013 at 3:51 AM, Chen Yang <[email protected]> wrote: >> On Wed, Jan 23, 2013 at 1:04 PM, Chen Yang <[email protected]> >> wrote: >>> From: Chen Yang <[email protected]> >>> 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 <[email protected]> >>> --- >>> 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 >>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in >>> the body of a message to [email protected] >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in >> the body of a message to [email protected] >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
