[PATCH v14 3/7] btrfs: add send stream v2 definitions

Omar Sandoval
2022-03-17T17:26:15Z

From: Omar Sandoval <osandov@fb.com>

This adds the definitions of the new commands for send stream version 2
and their respective attributes: fallocate, FS_IOC_SETFLAGS (a.k.a.
chattr), and encoded writes. It also documents two changes to the send
stream format in v2: the receiver shouldn't assume a maximum command
size, and the DATA attribute is encoded differently to allow for writes
larger than 64k. These will be implemented in subsequent changes, and
then the ioctl will accept the new version and flag.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
---
fs/btrfs/send.c | 2 +-
fs/btrfs/send.h | 40 ++++++++++++++++++++++++++++++++++----
include/uapi/linux/btrfs.h | 7 +++++++
3 files changed, 44 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 9363f625fa17..1f141de3a7d6 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -7459,7 +7459,7 @@ long btrfs_ioctl_send(struct inode *inode, struct btrfs_ioctl_send_args *arg)

sctx->clone_roots_cnt = arg->clone_sources_count;

- sctx->send_max_size = BTRFS_SEND_BUF_SIZE;
+ sctx->send_max_size = BTRFS_SEND_BUF_SIZE_V1;
sctx->send_buf = kvmalloc(sctx->send_max_size, GFP_KERNEL);
if (!sctx->send_buf) {
ret = -ENOMEM;
diff --git a/fs/btrfs/send.h b/fs/btrfs/send.h
index 67721e0281ba..805d8095209a 100644
--- a/fs/btrfs/send.h
+++ b/fs/btrfs/send.h
@@ -12,7 +12,11 @@
#define BTRFS_SEND_STREAM_MAGIC "btrfs-stream"
#define BTRFS_SEND_STREAM_VERSION 1

-#define BTRFS_SEND_BUF_SIZE SZ_64K
+/*
+ * In send stream v1, no command is larger than 64k. In send stream v2, no limit
+ * should be assumed.
+ */
+#define BTRFS_SEND_BUF_SIZE_V1 SZ_64K

enum btrfs_tlv_type {
BTRFS_TLV_U8,
@@ -80,16 +84,20 @@ enum btrfs_send_cmd {
BTRFS_SEND_C_MAX_V1 = 22,

/* Version 2 */
- BTRFS_SEND_C_MAX_V2 = 22,
+ BTRFS_SEND_C_FALLOCATE = 23,
+ BTRFS_SEND_C_SETFLAGS = 24,
+ BTRFS_SEND_C_ENCODED_WRITE = 25,
+ BTRFS_SEND_C_MAX_V2 = 25,

/* End */
- BTRFS_SEND_C_MAX = 22,
+ BTRFS_SEND_C_MAX = 25,
};

/* attributes in send stream */
enum {
BTRFS_SEND_A_UNSPEC = 0,

+ /* Version 1 */
BTRFS_SEND_A_UUID = 1,
BTRFS_SEND_A_CTRANSID = 2,

@@ -112,6 +120,11 @@ enum {
BTRFS_SEND_A_PATH_LINK = 17,

BTRFS_SEND_A_FILE_OFFSET = 18,
+ /*
+ * As of send stream v2, this attribute is special: it must be the last
+ * attribute in a command, its header contains only the type, and its
+ * length is implicitly the remaining length of the command.
+ */
BTRFS_SEND_A_DATA = 19,

BTRFS_SEND_A_CLONE_UUID = 20,
@@ -120,7 +133,26 @@ enum {
BTRFS_SEND_A_CLONE_OFFSET = 23,
BTRFS_SEND_A_CLONE_LEN = 24,

- BTRFS_SEND_A_MAX = 24,
+ BTRFS_SEND_A_MAX_V1 = 24,
+
+ /* Version 2 */
+ BTRFS_SEND_A_FALLOCATE_MODE = 25,
+
+ BTRFS_SEND_A_SETFLAGS_FLAGS = 26,
+
+ BTRFS_SEND_A_UNENCODED_FILE_LEN = 27,
+ BTRFS_SEND_A_UNENCODED_LEN = 28,
+ BTRFS_SEND_A_UNENCODED_OFFSET = 29,
+ /*
+ * COMPRESSION and ENCRYPTION default to NONE (0) if omitted from
+ * BTRFS_SEND_C_ENCODED_WRITE.
+ */
+ BTRFS_SEND_A_COMPRESSION = 30,
+ BTRFS_SEND_A_ENCRYPTION = 31,
+ BTRFS_SEND_A_MAX_V2 = 31,
+
+ /* End */
+ BTRFS_SEND_A_MAX = 31,
};

#ifdef __KERNEL__
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index d956b2993970..b6f26a434b10 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -777,6 +777,13 @@ struct btrfs_ioctl_received_subvol_args {
*/
#define BTRFS_SEND_FLAG_VERSION 0x8

+/*
+ * Send compressed data using the ENCODED_WRITE command instead of decompressing
+ * the data and sending it with the WRITE command. This requires protocol
+ * version >= 2.
+ */
+#define BTRFS_SEND_FLAG_COMPRESSED 0x10
+
#define BTRFS_SEND_FLAG_MASK \
(BTRFS_SEND_FLAG_NO_FILE_DATA | \
BTRFS_SEND_FLAG_OMIT_STREAM_HEADER | \
--
2.35.1