[PATCH v14 05/10] btrfs-progs: receive: process encoded_write commands

Omar Sandoval
2022-03-17T17:26:21Z

From: Boris Burkov <borisb@fb.com>

Add a new btrfs_send_op and support for both dumping and proper receive
processing which does actual encoded writes.

Encoded writes are only allowed on a file descriptor opened with an
extra flag that allows encoded writes, so we also add support for this
flag when opening or reusing a file for writing.

Signed-off-by: Boris Burkov <boris@bur.io>
---
cmds/receive-dump.c | 16 +++++-
cmds/receive.c | 48 ++++++++++++++++
common/send-stream.c | 29 ++++++++++
common/send-stream.h | 4 ++
ioctl.h | 132 +++++++++++++++++++++++++++++++++++++++++++
5 files changed, 228 insertions(+), 1 deletion(-)

diff --git a/cmds/receive-dump.c b/cmds/receive-dump.c
index 00ad4fd1..83701b62 100644
--- a/cmds/receive-dump.c
+++ b/cmds/receive-dump.c
@@ -318,6 +318,19 @@ static int print_update_extent(const char *path, u64 offset, u64 len,
offset, len);
}

+static int print_encoded_write(const char *path, const void *data, u64 offset,
+ u64 len, u64 unencoded_file_len,
+ u64 unencoded_len, u64 unencoded_offset,
+ u32 compression, u32 encryption, void *user)
+{
+ return PRINT_DUMP(user, path, "encoded_write",
+ "offset=%llu len=%llu, unencoded_file_len=%llu, "
+ "unencoded_len=%llu, unencoded_offset=%llu, "
+ "compression=%u, encryption=%u",
+ offset, len, unencoded_file_len, unencoded_len,
+ unencoded_offset, compression, encryption);
+}
+
struct btrfs_send_ops btrfs_print_send_ops = {
.subvol = print_subvol,
.snapshot = print_snapshot,
@@ -339,5 +352,6 @@ struct btrfs_send_ops btrfs_print_send_ops = {
.chmod = print_chmod,
.chown = print_chown,
.utimes = print_utimes,
- .update_extent = print_update_extent
+ .update_extent = print_update_extent,
+ .encoded_write = print_encoded_write,
};
diff --git a/cmds/receive.c b/cmds/receive.c
index d106e554..8226ca32 100644
--- a/cmds/receive.c
+++ b/cmds/receive.c
@@ -29,12 +29,14 @@
#include <assert.h>
#include <getopt.h>
#include <limits.h>
+#include <errno.h>

#include <sys/stat.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <sys/types.h>
+#include <sys/uio.h>
#include <sys/xattr.h>
#include <uuid/uuid.h>

@@ -49,6 +51,7 @@
#include "cmds/receive-dump.h"
#include "common/help.h"
#include "common/path-utils.h"
+#include "stubs.h"

struct btrfs_receive
{
@@ -982,6 +985,50 @@ static int process_update_extent(const char *path, u64 offset, u64 len,
return 0;
}

+static int process_encoded_write(const char *path, const void *data, u64 offset,
+ u64 len, u64 unencoded_file_len,
+ u64 unencoded_len, u64 unencoded_offset,
+ u32 compression, u32 encryption, void *user)
+{
+ int ret;
+ struct btrfs_receive *rctx = user;
+ char full_path[PATH_MAX];
+ struct iovec iov = { (char *)data, len };
+ struct btrfs_ioctl_encoded_io_args encoded = {
+ .iov = &iov,
+ .iovcnt = 1,
+ .offset = offset,
+ .len = unencoded_file_len,
+ .unencoded_len = unencoded_len,
+ .unencoded_offset = unencoded_offset,
+ .compression = compression,
+ .encryption = encryption,
+ };
+
+ if (encryption) {
+ error("encoded_write: encryption not supported");
+ return -EOPNOTSUPP;
+ }
+
+ ret = path_cat_out(full_path, rctx->full_subvol_path, path);
+ if (ret < 0) {
+ error("encoded_write: path invalid: %s", path);
+ return ret;
+ }
+
+ ret = open_inode_for_write(rctx, full_path);
+ if (ret < 0)
+ return ret;
+
+ ret = ioctl(rctx->write_fd, BTRFS_IOC_ENCODED_WRITE, &encoded);
+ if (ret < 0) {
+ ret = -errno;
+ error("encoded_write: writing to %s failed: %m", path);
+ return ret;
+ }
+ return 0;
+}
+
static struct btrfs_send_ops send_ops = {
.subvol = process_subvol,
.snapshot = process_snapshot,
@@ -1004,6 +1051,7 @@ static struct btrfs_send_ops send_ops = {
.chown = process_chown,
.utimes = process_utimes,
.update_extent = process_update_extent,
+ .encoded_write = process_encoded_write,
};

static int do_receive(struct btrfs_receive *rctx, const char *tomnt,
diff --git a/common/send-stream.c b/common/send-stream.c
index 81a830d9..ce7c40f5 100644
--- a/common/send-stream.c
+++ b/common/send-stream.c
@@ -357,6 +357,8 @@ static int read_and_process_cmd(struct btrfs_send_stream *sctx)
struct timespec mt;
u8 uuid[BTRFS_UUID_SIZE];
u8 clone_uuid[BTRFS_UUID_SIZE];
+ u32 compression;
+ u32 encryption;
u64 tmp;
u64 tmp2;
u64 ctransid;
@@ -366,6 +368,9 @@ static int read_and_process_cmd(struct btrfs_send_stream *sctx)
u64 clone_offset;
u64 offset;
u64 ino;
+ u64 unencoded_file_len;
+ u64 unencoded_len;
+ u64 unencoded_offset;
int len;
int xattr_len;

@@ -452,6 +457,30 @@ static int read_and_process_cmd(struct btrfs_send_stream *sctx)
TLV_GET(sctx, BTRFS_SEND_A_DATA, &data, &len);
ret = sctx->ops->write(path, data, offset, len, sctx->user);
break;
+ case BTRFS_SEND_C_ENCODED_WRITE:
+ TLV_GET_STRING(sctx, BTRFS_SEND_A_PATH, &path);
+ TLV_GET_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, &offset);
+ TLV_GET_U64(sctx, BTRFS_SEND_A_UNENCODED_FILE_LEN,
+ &unencoded_file_len);
+ TLV_GET_U64(sctx, BTRFS_SEND_A_UNENCODED_LEN, &unencoded_len);
+ TLV_GET_U64(sctx, BTRFS_SEND_A_UNENCODED_OFFSET,
+ &unencoded_offset);
+ /* Compression and encryption default to none if omitted. */
+ if (sctx->cmd_attrs[BTRFS_SEND_A_COMPRESSION].data)
+ TLV_GET_U32(sctx, BTRFS_SEND_A_COMPRESSION, &compression);
+ else
+ compression = BTRFS_ENCODED_IO_COMPRESSION_NONE;
+ if (sctx->cmd_attrs[BTRFS_SEND_A_ENCRYPTION].data)
+ TLV_GET_U32(sctx, BTRFS_SEND_A_ENCRYPTION, &encryption);
+ else
+ encryption = BTRFS_ENCODED_IO_ENCRYPTION_NONE;
+ TLV_GET(sctx, BTRFS_SEND_A_DATA, &data, &len);
+ ret = sctx->ops->encoded_write(path, data, offset, len,
+ unencoded_file_len,
+ unencoded_len, unencoded_offset,
+ compression, encryption,
+ sctx->user);
+ break;
case BTRFS_SEND_C_CLONE:
TLV_GET_STRING(sctx, BTRFS_SEND_A_PATH, &path);
TLV_GET_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, &offset);
diff --git a/common/send-stream.h b/common/send-stream.h
index 2de51eac..44abbc9d 100644
--- a/common/send-stream.h
+++ b/common/send-stream.h
@@ -53,6 +53,10 @@ struct btrfs_send_ops {
struct timespec *mt, struct timespec *ct,
void *user);
int (*update_extent)(const char *path, u64 offset, u64 len, void *user);
+ int (*encoded_write)(const char *path, const void *data, u64 offset,
+ u64 len, u64 unencoded_file_len, u64 unencoded_len,
+ u64 unencoded_offset, u32 compression,
+ u32 encryption, void *user);
};

int btrfs_read_and_process_send_stream(int fd,
diff --git a/ioctl.h b/ioctl.h
index 368a87b2..8adf63c2 100644
--- a/ioctl.h
+++ b/ioctl.h
@@ -777,6 +777,134 @@ struct btrfs_ioctl_get_subvol_rootref_args {
};
BUILD_ASSERT(sizeof(struct btrfs_ioctl_get_subvol_rootref_args) == 4096);

+/*
+ * Data and metadata for an encoded read or write.
+ *
+ * Encoded I/O bypasses any encoding automatically done by the filesystem (e.g.,
+ * compression). This can be used to read the compressed contents of a file or
+ * write pre-compressed data directly to a file.
+ *
+ * BTRFS_IOC_ENCODED_READ and BTRFS_IOC_ENCODED_WRITE are essentially
+ * preadv/pwritev with additional metadata about how the data is encoded and the
+ * size of the unencoded data.
+ *
+ * BTRFS_IOC_ENCODED_READ fills the given iovecs with the encoded data, fills
+ * the metadata fields, and returns the size of the encoded data. It reads one
+ * extent per call. It can also read data which is not encoded.
+ *
+ * BTRFS_IOC_ENCODED_WRITE uses the metadata fields, writes the encoded data
+ * from the iovecs, and returns the size of the encoded data. Note that the
+ * encoded data is not validated when it is written; if it is not valid (e.g.,
+ * it cannot be decompressed), then a subsequent read may return an error.
+ *
+ * Since the filesystem page cache contains decoded data, encoded I/O bypasses
+ * the page cache. Encoded I/O requires CAP_SYS_ADMIN.
+ */
+struct btrfs_ioctl_encoded_io_args {
+ /* Input parameters for both reads and writes. */
+
+ /*
+ * iovecs containing encoded data.
+ *
+ * For reads, if the size of the encoded data is larger than the sum of
+ * iov[n].iov_len for 0 <= n < iovcnt, then the ioctl fails with
+ * ENOBUFS.
+ *
+ * For writes, the size of the encoded data is the sum of iov[n].iov_len
+ * for 0 <= n < iovcnt. This must be less than 128 KiB (this limit may
+ * increase in the future). This must also be less than or equal to
+ * unencoded_len.
+ */
+ const struct iovec __user *iov;
+ /* Number of iovecs. */
+ unsigned long iovcnt;
+ /*
+ * Offset in file.
+ *
+ * For writes, must be aligned to the sector size of the filesystem.
+ */
+ __s64 offset;
+ /* Currently must be zero. */
+ __u64 flags;
+
+ /*
+ * For reads, the following members are output parameters that will
+ * contain the returned metadata for the encoded data.
+ * For writes, the following members must be set to the metadata for the
+ * encoded data.
+ */
+
+ /*
+ * Length of the data in the file.
+ *
+ * Must be less than or equal to unencoded_len - unencoded_offset. For
+ * writes, must be aligned to the sector size of the filesystem unless
+ * the data ends at or beyond the current end of the file.
+ */
+ __u64 len;
+ /*
+ * Length of the unencoded (i.e., decrypted and decompressed) data.
+ *
+ * For writes, must be no more than 128 KiB (this limit may increase in
+ * the future). If the unencoded data is actually longer than
+ * unencoded_len, then it is truncated; if it is shorter, then it is
+ * extended with zeroes.
+ */
+ __u64 unencoded_len;
+ /*
+ * Offset from the first byte of the unencoded data to the first byte of
+ * logical data in the file.
+ *
+ * Must be less than unencoded_len.
+ */
+ __u64 unencoded_offset;
+ /*
+ * BTRFS_ENCODED_IO_COMPRESSION_* type.
+ *
+ * For writes, must not be BTRFS_ENCODED_IO_COMPRESSION_NONE.
+ */
+ __u32 compression;
+ /* Currently always BTRFS_ENCODED_IO_ENCRYPTION_NONE. */
+ __u32 encryption;
+ /*
+ * Reserved for future expansion.
+ *
+ * For reads, always returned as zero. Users should check for non-zero
+ * bytes. If there are any, then the kernel has a newer version of this
+ * structure with additional information that the user definition is
+ * missing.
+ *
+ * For writes, must be zeroed.
+ */
+ __u8 reserved[64];
+};
+
+/* Data is not compressed. */
+#define BTRFS_ENCODED_IO_COMPRESSION_NONE 0
+/* Data is compressed as a single zlib stream. */
+#define BTRFS_ENCODED_IO_COMPRESSION_ZLIB 1
+/*
+ * Data is compressed as a single zstd frame with the windowLog compression
+ * parameter set to no more than 17.
+ */
+#define BTRFS_ENCODED_IO_COMPRESSION_ZSTD 2
+/*
+ * Data is compressed sector by sector (using the sector size indicated by the
+ * name of the constant) with LZO1X and wrapped in the format documented in
+ * fs/btrfs/lzo.c. For writes, the compression sector size must match the
+ * filesystem sector size.
+ */
+#define BTRFS_ENCODED_IO_COMPRESSION_LZO_4K 3
+#define BTRFS_ENCODED_IO_COMPRESSION_LZO_8K 4
+#define BTRFS_ENCODED_IO_COMPRESSION_LZO_16K 5
+#define BTRFS_ENCODED_IO_COMPRESSION_LZO_32K 6
+#define BTRFS_ENCODED_IO_COMPRESSION_LZO_64K 7
+#define BTRFS_ENCODED_IO_COMPRESSION_TYPES 8
+
+/* Data is not encrypted. */
+#define BTRFS_ENCODED_IO_ENCRYPTION_NONE 0
+#define BTRFS_ENCODED_IO_ENCRYPTION_TYPES 1
+
/* Error codes as returned by the kernel */
enum btrfs_err_code {
notused,
@@ -951,6 +1079,10 @@ static inline char *btrfs_err_str(enum btrfs_err_code err_code)
struct btrfs_ioctl_ino_lookup_user_args)
#define BTRFS_IOC_SNAP_DESTROY_V2 _IOW(BTRFS_IOCTL_MAGIC, 63, \
struct btrfs_ioctl_vol_args_v2)
+#define BTRFS_IOC_ENCODED_READ _IOR(BTRFS_IOCTL_MAGIC, 64, \
+ struct btrfs_ioctl_encoded_io_args)
+#define BTRFS_IOC_ENCODED_WRITE _IOW(BTRFS_IOCTL_MAGIC, 64, \
+ struct btrfs_ioctl_encoded_io_args)

#ifdef __cplusplus
}
--
2.35.1