[PATCH 08/11] btrfs-progs: receive: process fallocate commands

[Omar Sandoval <osandov@osandov.com>]

From: Boris Burkov <boris@bur.io>

Send stream v2 can emit fallocate commands, so receive must support them
as well. The implementation simply passes along the arguments to the
syscall. Note that mode is encoded as a u32 in send stream but fallocate
takes an int, so there is a unsigned->signed conversion there.

Signed-off-by: Boris Burkov <boris@bur.io>
---
 cmds/receive-dump.c  |  9 +++++++++
 cmds/receive.c       | 26 ++++++++++++++++++++++++++
 common/send-stream.c |  9 +++++++++
 common/send-stream.h |  2 ++
 4 files changed, 46 insertions(+)

diff --git a/cmds/receive-dump.c b/cmds/receive-dump.c
index 20ec2b70..acc0ba32 100644
--- a/cmds/receive-dump.c
+++ b/cmds/receive-dump.c
@@ -329,6 +329,14 @@ static int print_encoded_write(const char *path, const void *data, u64 offset,
 			  unencoded_offset, compression, encryption);
 }
 
+static int print_fallocate(const char *path, int mode, u64 offset, u64 len,
+			   void *user)
+{
+	return PRINT_DUMP(user, path, "fallocate",
+			  "mode=%d offset=%llu len=%llu",
+			  mode, offset, len);
+}
+
 struct btrfs_send_ops btrfs_print_send_ops = {
 	.subvol = print_subvol,
 	.snapshot = print_snapshot,
@@ -352,4 +360,5 @@ struct btrfs_send_ops btrfs_print_send_ops = {
 	.utimes = print_utimes,
 	.update_extent = print_update_extent,
 	.encoded_write = print_encoded_write,
+	.fallocate = print_fallocate,
 };
diff --git a/cmds/receive.c b/cmds/receive.c
index c67d4653..5c0930cb 100644
--- a/cmds/receive.c
+++ b/cmds/receive.c
@@ -1356,6 +1356,31 @@ out:
 	return ret;
 }
 
+static int process_fallocate(const char *path, int mode, u64 offset, u64 len,
+			     void *user)
+{
+	int ret;
+	struct btrfs_receive *rctx = user;
+	char full_path[PATH_MAX];
+
+	ret = path_cat_out(full_path, rctx->full_subvol_path, path);
+	if (ret < 0) {
+		error("fallocate: path invalid: %s", path);
+		goto out;
+	}
+	ret = open_inode_for_write(rctx, full_path, false);
+	if (ret < 0)
+		goto out;
+	ret = fallocate(rctx->write_fd, mode, offset, len);
+	if (ret < 0) {
+		ret = -errno;
+		error("fallocate: fallocate on %s failed: %m", path);
+		goto out;
+	}
+out:
+	return ret;
+}
+
 static struct btrfs_send_ops send_ops = {
 	.subvol = process_subvol,
 	.snapshot = process_snapshot,
@@ -1379,6 +1404,7 @@ static struct btrfs_send_ops send_ops = {
 	.utimes = process_utimes,
 	.update_extent = process_update_extent,
 	.encoded_write = process_encoded_write,
+	.fallocate = process_fallocate,
 };
 
 static int do_receive(struct btrfs_receive *rctx, const char *tomnt,
diff --git a/common/send-stream.c b/common/send-stream.c
index 1376e00b..d455cdfb 100644
--- a/common/send-stream.c
+++ b/common/send-stream.c
@@ -369,6 +369,7 @@ static int read_and_process_cmd(struct btrfs_send_stream *sctx)
 	u64 unencoded_offset;
 	int len;
 	int xattr_len;
+	int fallocate_mode;
 
 	ret = read_cmd(sctx);
 	if (ret)
@@ -514,6 +515,14 @@ static int read_and_process_cmd(struct btrfs_send_stream *sctx)
 	case BTRFS_SEND_C_END:
 		ret = 1;
 		break;
+	case BTRFS_SEND_C_FALLOCATE:
+		TLV_GET_STRING(sctx, BTRFS_SEND_A_PATH, &path);
+		TLV_GET_U32(sctx, BTRFS_SEND_A_FALLOCATE_MODE, &fallocate_mode);
+		TLV_GET_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, &offset);
+		TLV_GET_U64(sctx, BTRFS_SEND_A_SIZE, &tmp);
+		ret = sctx->ops->fallocate(path, fallocate_mode, offset, tmp,
+					   sctx->user);
+		break;
 	}
 
 tlv_get_failed:
diff --git a/common/send-stream.h b/common/send-stream.h
index 607bc007..a58739bb 100644
--- a/common/send-stream.h
+++ b/common/send-stream.h
@@ -70,6 +70,8 @@ struct btrfs_send_ops {
 			     u64 len, u64 unencoded_file_len, u64 unencoded_len,
 			     u64 unencoded_offset, u32 compression,
 			     u32 encryption, void *user);
+	int (*fallocate)(const char *path, int mode, u64 offset, u64 len,
+			 void *user);
 };
 
 int btrfs_read_and_process_send_stream(int fd,
-- 
2.28.0