[PATCH v7 0/4] btrfs-progs: image: new data dump feature

[PATCH v7 0/4] btrfs-progs: image: new data dump feature

[Qu Wenruo]

This patchset includes the following features:

- Introduce data dump feature to dump the whole fs.
  This will introduce a new magic number to prevent old btrfs-image to
  hit failure as the item size limit is enlarged.
  Patch 1 and 2.

- Reduce memory usage for compressed data dump restore
  This is mostly due to the fact that we have much larger
  max_pending_size introduced by data dump(256K -> 256M).
  Using 4 * max_pending_size for each decompress thread as buffer is way
  too expensive now.
  Use proper inflate() to replace uncompress() calls.
  Patch 3

- A fix for small dev extent size mismatch with superblock
  This no longer affects single device dump restore, thus it's only
  for multi-device dump restore.
  Patch 4

Changelog:
v2:
- New small fixes:
  * Fix a confusing error message due to unpopulated errno
  * Output error message for chunk tree build error
  
- Fix a regression of previous version
  Patch "btrfs-progs: image: Rework how we search chunk tree blocks"
  deleted a "ret = 0" line which could cause false early exit.

- Reduce memory usage for data dump

v2.1:
- Rebased to devel branch
  Removing 4 already merged patches from the patchset.

- Re-order the patchset
  Put small and independent patches at the top of queue, and put the
  data dump related feature at the end.

- Fix -Wmaybe-uninitialized warnings
  Strangely, D=1 won't trigger these warnings thus they sneak into v2
  without being detected.

- Fix FROM: line
  Reverted to old smtp setup. The new setup will override FROM: line,
  messing up the name of author.

v3:
- Fix a wrong option in error string
- Fix a bug that we always dump data extents

v4:
- Rebased to latest devel branch
- Add a new small fix to kill the tiny dev extent size mismatch.

v5:
- Rebased to latest devel branch
- Checkpatch fixes

v6:
- Rebased to latest devel branch
  No conflicts at all.

v7:
- Rebased to latest devel branch
  No conflicts at all.

- Hide the data dump feature behind the experimental features
  Now to make "btrfs-image -d" work, one must enable experimental
  features, or "btrfs-image -d" will only output an error message.

  And if experimental features are not enabled, the new header format
  will also be disabled, so that btrfs-image can't detect the new format
  either.

  Although the "-d" option is still enabled for the non-experimental
  build.

  This only affects the 2nd patch, the remaining patches are not
  touched.

Qu Wenruo (4):
  btrfs-progs: image: introduce framework for more dump versions
  btrfs-progs: image: introduce -d option to dump data
  btrfs-progs: image: reduce memory requirement for decompression
  btrfs-progs: image: fix restored image size misalignment

 image/main.c     | 358 ++++++++++++++++++++++++++++++++++-------------
 image/metadump.h |  12 +-
 2 files changed, 273 insertions(+), 97 deletions(-)

-- 
2.32.0

[PATCH v7 1/4] btrfs-progs: image: introduce framework for more dump versions

[Qu Wenruo]

The original dump format only contains a @magic member to verify the
format, this means if we want to introduce new on-disk format or change
certain size limit, we can only introduce new magic as version.

This patch will introduce the framework to allow multiple magic numbers to
co-exist for further functions.

This patch will introduce the following members for each dump version.

- max_pending_size
  The threshold size for an cluster. It's not a hard limit but a soft
  one. One cluster can go larger than max_pending_size for one item, but
  next item would go to next cluster.

- magic_cpu
  The magic number in CPU endian.

- extra_sb_flags
  If the super block of this restore needs extra super block flags like
  BTRFS_SUPER_FLAG_METADUMP_V2.
  For incoming data dump feature, we don't need any extra super block
  flags.

This change also implies that all image dumps will use the same magic
for all clusters. No mixing is allowed, as we will use the first cluster
to determine the dump version.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 image/main.c     | 72 ++++++++++++++++++++++++++++++++++++++++++------
 image/metadump.h | 12 ++++++--
 2 files changed, 73 insertions(+), 11 deletions(-)

diff --git a/image/main.c b/image/main.c
index b29e68f80863..65a42ad7d85d 100644
--- a/image/main.c
+++ b/image/main.c
@@ -45,6 +45,19 @@
 
 #define MAX_WORKER_THREADS	(32)
 
+const struct dump_version dump_versions[] = {
+	/*
+	 * The original format, which only supports tree blocks and
+	 * free space cache dump.
+	 */
+	{ .version = 0,
+	  .max_pending_size = SZ_256K,
+	  .magic_cpu = 0xbd5c25e27295668bULL,
+	  .extra_sb_flags = 1 }
+};
+
+const struct dump_version *current_version = &dump_versions[0];
+
 struct async_work {
 	struct list_head list;
 	struct list_head ordered;
@@ -406,7 +419,7 @@ static void meta_cluster_init(struct metadump_struct *md, u64 start)
 	md->num_items = 0;
 	md->num_ready = 0;
 	header = &md->cluster.header;
-	header->magic = cpu_to_le64(HEADER_MAGIC);
+	header->magic = cpu_to_le64(current_version->magic_cpu);
 	header->bytenr = cpu_to_le64(start);
 	header->nritems = cpu_to_le32(0);
 	header->compress = md->compress_level > 0 ?
@@ -718,7 +731,7 @@ static int add_extent(u64 start, u64 size, struct metadump_struct *md,
 {
 	int ret;
 	if (md->data != data ||
-	    md->pending_size + size > MAX_PENDING_SIZE ||
+	    md->pending_size + size > current_version->max_pending_size ||
 	    md->pending_start + md->pending_size != start) {
 		ret = flush_pending(md, 0);
 		if (ret)
@@ -1047,7 +1060,8 @@ static void update_super_old(u8 *buffer)
 	u32 sectorsize = btrfs_super_sectorsize(super);
 	u64 flags = btrfs_super_flags(super);
 
-	flags |= BTRFS_SUPER_FLAG_METADUMP;
+	if (current_version->extra_sb_flags)
+		flags |= BTRFS_SUPER_FLAG_METADUMP;
 	btrfs_set_super_flags(super, flags);
 
 	key = (struct btrfs_disk_key *)(super->sys_chunk_array);
@@ -1147,7 +1161,8 @@ finish:
 	if (mdres->clear_space_cache)
 		btrfs_set_super_cache_generation(super, 0);
 
-	flags |= BTRFS_SUPER_FLAG_METADUMP_V2;
+	if (current_version->extra_sb_flags)
+		flags |= BTRFS_SUPER_FLAG_METADUMP_V2;
 	btrfs_set_super_flags(super, flags);
 	btrfs_set_super_sys_array_size(super, new_array_size);
 	btrfs_set_super_num_devices(super, 1);
@@ -1337,7 +1352,7 @@ static void *restore_worker(void *data)
 	u8 *outbuf;
 	int outfd;
 	int ret;
-	int compress_size = MAX_PENDING_SIZE * 4;
+	int compress_size = current_version->max_pending_size * 4;
 
 	outfd = fileno(mdres->out);
 	buffer = malloc(compress_size);
@@ -1490,6 +1505,42 @@ static void mdrestore_destroy(struct mdrestore_struct *mdres, int num_threads)
 	free(mdres->original_super);
 }
 
+static int detect_version(FILE *in)
+{
+	struct meta_cluster *cluster;
+	u8 buf[BLOCK_SIZE];
+	bool found = false;
+	int i;
+	int ret;
+
+	if (fseek(in, 0, SEEK_SET) < 0) {
+		error("seek failed: %m");
+		return -errno;
+	}
+	ret = fread(buf, BLOCK_SIZE, 1, in);
+	if (!ret) {
+		error("failed to read header");
+		return -EIO;
+	}
+
+	fseek(in, 0, SEEK_SET);
+	cluster = (struct meta_cluster *)buf;
+	for (i = 0; i < ARRAY_SIZE(dump_versions); i++) {
+		if (le64_to_cpu(cluster->header.magic) ==
+		    dump_versions[i].magic_cpu) {
+			found = true;
+			current_version = &dump_versions[i];
+			break;
+		}
+	}
+
+	if (!found) {
+		error("unrecognized header format");
+		return -EINVAL;
+	}
+	return 0;
+}
+
 static int mdrestore_init(struct mdrestore_struct *mdres,
 			  FILE *in, FILE *out, int old_restore,
 			  int num_threads, int fixup_offset,
@@ -1497,6 +1548,9 @@ static int mdrestore_init(struct mdrestore_struct *mdres,
 {
 	int i, ret = 0;
 
+	ret = detect_version(in);
+	if (ret < 0)
+		return ret;
 	memset(mdres, 0, sizeof(*mdres));
 	pthread_cond_init(&mdres->cond, NULL);
 	pthread_mutex_init(&mdres->mutex, NULL);
@@ -1850,7 +1904,7 @@ static int search_for_chunk_blocks(struct mdrestore_struct *mdres)
 	u64 current_cluster = 0, bytenr;
 	u64 item_bytenr;
 	u32 bufsize, nritems, i;
-	u32 max_size = MAX_PENDING_SIZE * 2;
+	u32 max_size = current_version->max_pending_size * 2;
 	u8 *buffer, *tmp = NULL;
 	int ret = 0;
 
@@ -1903,7 +1957,7 @@ static int search_for_chunk_blocks(struct mdrestore_struct *mdres)
 		ret = 0;
 
 		header = &cluster->header;
-		if (le64_to_cpu(header->magic) != HEADER_MAGIC ||
+		if (le64_to_cpu(header->magic) != current_version->magic_cpu ||
 		    le64_to_cpu(header->bytenr) != current_cluster) {
 			error("bad header in metadump image");
 			ret = -EIO;
@@ -2102,7 +2156,7 @@ static int build_chunk_tree(struct mdrestore_struct *mdres,
 	ret = 0;
 
 	header = &cluster->header;
-	if (le64_to_cpu(header->magic) != HEADER_MAGIC ||
+	if (le64_to_cpu(header->magic) != current_version->magic_cpu ||
 	    le64_to_cpu(header->bytenr) != 0) {
 		error("bad header in metadump image");
 		return -EIO;
@@ -2675,7 +2729,7 @@ static int restore_metadump(const char *input, FILE *out, int old_restore,
 			break;
 
 		header = &cluster->header;
-		if (le64_to_cpu(header->magic) != HEADER_MAGIC ||
+		if (le64_to_cpu(header->magic) != current_version->magic_cpu ||
 		    le64_to_cpu(header->bytenr) != bytenr) {
 			error("bad header in metadump image");
 			ret = -EIO;
diff --git a/image/metadump.h b/image/metadump.h
index 57bc3bf285b0..bcffbd4722b0 100644
--- a/image/metadump.h
+++ b/image/metadump.h
@@ -22,8 +22,6 @@
 #include "kernel-lib/list.h"
 #include "kernel-shared/ctree.h"
 
-#define HEADER_MAGIC		0xbd5c25e27295668bULL
-#define MAX_PENDING_SIZE	SZ_256K
 #define BLOCK_SIZE		SZ_1K
 #define BLOCK_MASK		(BLOCK_SIZE - 1)
 
@@ -33,6 +31,16 @@
 #define COMPRESS_NONE		0
 #define COMPRESS_ZLIB		1
 
+struct dump_version {
+	u64 magic_cpu;
+	int version;
+	int max_pending_size;
+	unsigned int extra_sb_flags:1;
+};
+
+extern const struct dump_version dump_versions[];
+const extern struct dump_version *current_version;
+
 struct meta_cluster_item {
 	__le64 bytenr;
 	__le32 size;
-- 
2.32.0

[PATCH v7 2/4] btrfs-progs: image: introduce -d option to dump data

[Qu Wenruo]

This new experimental data dump feature will dump the whole image, not
only the existing tree blocks but also all its data extents(*).

This feature will rely on the new dump format (_DUmP_v1), as it needs
extra large extent size limit, and older btrfs-image dump can't handle
such large item/cluster size.

Since we're dumping all extents including data extents, for the restored
image there is no need to use any extra super block flags to inform
kernel.
Kernel should just treat the restored image as any ordinary btrfs.

This new feature will be hidden behind the experimental features, that's
to say, if --enable-experimental is not enabled, although we still have
the option, it will not do anything but output an error message.

*: The data extents will be dumped as is, that's to say, even for
preallocated extent, its (meaningless) data will be read out and
dumpped.
This behavior will cause extra space usage for the image, but we can
skip all the complex partially shared preallocated extent check.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 image/main.c | 62 ++++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 50 insertions(+), 12 deletions(-)

diff --git a/image/main.c b/image/main.c
index 65a42ad7d85d..b57120875f72 100644
--- a/image/main.c
+++ b/image/main.c
@@ -53,7 +53,17 @@ const struct dump_version dump_versions[] = {
 	{ .version = 0,
 	  .max_pending_size = SZ_256K,
 	  .magic_cpu = 0xbd5c25e27295668bULL,
-	  .extra_sb_flags = 1 }
+	  .extra_sb_flags = 1 },
+#if EXPERIMENTAL
+	/*
+	 * The newer format, with much larger item size to contain
+	 * any data extent.
+	 */
+	{ .version = 1,
+	  .max_pending_size = SZ_256M,
+	  .magic_cpu = 0x31765f506d55445fULL, /* ascii _DUmP_v1, no null */
+	  .extra_sb_flags = 0 },
+#endif
 };
 
 const struct dump_version *current_version = &dump_versions[0];
@@ -455,10 +465,14 @@ static void metadump_destroy(struct metadump_struct *md, int num_threads)
 
 static int metadump_init(struct metadump_struct *md, struct btrfs_root *root,
 			 FILE *out, int num_threads, int compress_level,
-			 enum sanitize_mode sanitize_names)
+			 bool dump_data, enum sanitize_mode sanitize_names)
 {
 	int i, ret = 0;
 
+	/* We need larger item/cluster limit for data extents */
+	if (dump_data)
+		current_version = &dump_versions[1];
+
 	memset(md, 0, sizeof(*md));
 	INIT_LIST_HEAD(&md->list);
 	INIT_LIST_HEAD(&md->ordered);
@@ -886,7 +900,7 @@ static int copy_space_cache(struct btrfs_root *root,
 }
 
 static int copy_from_extent_tree(struct metadump_struct *metadump,
-				 struct btrfs_path *path)
+				 struct btrfs_path *path, bool dump_data)
 {
 	struct btrfs_root *extent_root;
 	struct extent_buffer *leaf;
@@ -951,9 +965,15 @@ static int copy_from_extent_tree(struct metadump_struct *metadump,
 			ei = btrfs_item_ptr(leaf, path->slots[0],
 					    struct btrfs_extent_item);
 			if (btrfs_extent_flags(leaf, ei) &
-			    BTRFS_EXTENT_FLAG_TREE_BLOCK) {
+			    BTRFS_EXTENT_FLAG_TREE_BLOCK ||
+			    (dump_data && (btrfs_extent_flags(leaf, ei) &
+					   BTRFS_EXTENT_FLAG_DATA))) {
+				bool is_data;
+
+				is_data = btrfs_extent_flags(leaf, ei) &
+					  BTRFS_EXTENT_FLAG_DATA;
 				ret = add_extent(bytenr, num_bytes, metadump,
-						 0);
+						 is_data);
 				if (ret) {
 					error("unable to add block %llu: %d",
 						(unsigned long long)bytenr, ret);
@@ -976,7 +996,7 @@ static int copy_from_extent_tree(struct metadump_struct *metadump,
 
 static int create_metadump(const char *input, FILE *out, int num_threads,
 			   int compress_level, enum sanitize_mode sanitize,
-			   int walk_trees)
+			   int walk_trees, bool dump_data)
 {
 	struct btrfs_root *root;
 	struct btrfs_path path;
@@ -991,7 +1011,7 @@ static int create_metadump(const char *input, FILE *out, int num_threads,
 	}
 
 	ret = metadump_init(&metadump, root, out, num_threads,
-			    compress_level, sanitize);
+			    compress_level, dump_data, sanitize);
 	if (ret) {
 		error("failed to initialize metadump: %d", ret);
 		close_ctree(root);
@@ -1023,7 +1043,7 @@ static int create_metadump(const char *input, FILE *out, int num_threads,
 			goto out;
 		}
 	} else {
-		ret = copy_from_extent_tree(&metadump, &path);
+		ret = copy_from_extent_tree(&metadump, &path, dump_data);
 		if (ret) {
 			err = ret;
 			goto out;
@@ -2929,6 +2949,7 @@ static void print_usage(int ret)
 	printf("\t-s      \tsanitize file names, use once to just use garbage, use twice if you want crc collisions\n");
 	printf("\t-w      \twalk all trees instead of using extent tree, do this if your extent tree is broken\n");
 	printf("\t-m	   \trestore for multiple devices\n");
+	printf("\t-d	   \talso dump data, conflicts with -w\n");
 	printf("\n");
 	printf("\tIn the dump mode, source is the btrfs device and target is the output file (use '-' for stdout).\n");
 	printf("\tIn the restore mode, source is the dumped image and target is the btrfs device/file.\n");
@@ -2948,6 +2969,7 @@ int BOX_MAIN(image)(int argc, char *argv[])
 	int ret;
 	enum sanitize_mode sanitize = SANITIZE_NONE;
 	int dev_cnt = 0;
+	bool dump_data = false;
 	int usage_error = 0;
 	FILE *out;
 
@@ -2956,7 +2978,7 @@ int BOX_MAIN(image)(int argc, char *argv[])
 			{ "help", no_argument, NULL, GETOPT_VAL_HELP},
 			{ NULL, 0, NULL, 0 }
 		};
-		int c = getopt_long(argc, argv, "rc:t:oswm", long_options, NULL);
+		int c = getopt_long(argc, argv, "rc:t:oswmd", long_options, NULL);
 		if (c < 0)
 			break;
 		switch (c) {
@@ -2996,6 +3018,9 @@ int BOX_MAIN(image)(int argc, char *argv[])
 			create = 0;
 			multi_devices = 1;
 			break;
+		case 'd':
+			dump_data = true;
+			break;
 		case GETOPT_VAL_HELP:
 		default:
 			print_usage(c != GETOPT_VAL_HELP);
@@ -3008,16 +3033,28 @@ int BOX_MAIN(image)(int argc, char *argv[])
 
 	dev_cnt = argc - optind - 1;
 
+#if !EXPERIMENTAL
+	if (dump_data) {
+		error(
+"data dump feature is experimental and is not configured in this build");
+		print_usage(1);
+	}
+#endif
 	if (create) {
 		if (old_restore) {
 			error(
 			"create and restore cannot be used at the same time");
 			usage_error++;
 		}
+		if (dump_data && walk_trees) {
+			error("-d conflicts with -w option");
+			usage_error++;
+		}
 	} else {
-		if (walk_trees || sanitize != SANITIZE_NONE || compress_level) {
+		if (walk_trees || sanitize != SANITIZE_NONE || compress_level ||
+		    dump_data) {
 			error(
-			"using -w, -s, -c options for restore makes no sense");
+		"using -w, -s, -c, -d options for restore makes no sense");
 			usage_error++;
 		}
 		if (multi_devices && dev_cnt < 2) {
@@ -3070,7 +3107,8 @@ int BOX_MAIN(image)(int argc, char *argv[])
 		}
 
 		ret = create_metadump(source, out, num_threads,
-				      compress_level, sanitize, walk_trees);
+				      compress_level, sanitize, walk_trees,
+				      dump_data);
 	} else {
 		ret = restore_metadump(source, out, old_restore, num_threads,
 				       0, target, multi_devices);
-- 
2.32.0

[PATCH v7 3/4] btrfs-progs: image: reduce memory requirement for decompression

[Qu Wenruo]

With recent change to enlarge max_pending_size to 256M for data dump,
the decompress code requires quite a lot of memory space. (256M * 4).

The main reason behind it is, we're using wrapped uncompress() function
call, which needs the buffer to be large enough to contain the
decompressed data.

This patch will re-work the decompress work to use inflate() which can
resume it decompression so that we can use a much smaller buffer size.

This patch choose to use 512K buffer size.

Now the memory consumption for restore is reduced to
 Cluster data size + 512K * nr_running_threads

Instead of the original one:
 Cluster data size + 1G * nr_running_threads

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 image/main.c | 222 +++++++++++++++++++++++++++++++++------------------
 1 file changed, 146 insertions(+), 76 deletions(-)

diff --git a/image/main.c b/image/main.c
index b57120875f72..c622c544b5d3 100644
--- a/image/main.c
+++ b/image/main.c
@@ -1363,130 +1363,200 @@ static void write_backup_supers(int fd, u8 *buf)
 	}
 }
 
-static void *restore_worker(void *data)
+/*
+ * Restore one item.
+ *
+ * For uncompressed data, it's just reading from work->buf then write to output.
+ * For compressed data, since we can have very large decompressed data
+ * (up to 256M), we need to consider memory usage. So here we will fill buffer
+ * then write the decompressed buffer to output.
+ */
+static int restore_one_work(struct mdrestore_struct *mdres,
+			    struct async_work *async, u8 *buffer, int bufsize)
 {
-	struct mdrestore_struct *mdres = (struct mdrestore_struct *)data;
-	struct async_work *async;
-	size_t size;
-	u8 *buffer;
-	u8 *outbuf;
-	int outfd;
+	z_stream strm;
+	int buf_offset = 0;	/* offset inside work->buffer */
+	int out_offset = 0;	/* offset for output */
+	int out_len;
+	int outfd = fileno(mdres->out);
+	int compress_method = mdres->compress_method;
 	int ret;
-	int compress_size = current_version->max_pending_size * 4;
 
-	outfd = fileno(mdres->out);
-	buffer = malloc(compress_size);
-	if (!buffer) {
-		error("not enough memory for restore worker buffer");
-		pthread_mutex_lock(&mdres->mutex);
-		if (!mdres->error)
-			mdres->error = -ENOMEM;
-		pthread_mutex_unlock(&mdres->mutex);
-		pthread_exit(NULL);
+	ASSERT(is_power_of_2(bufsize));
+
+	if (compress_method == COMPRESS_ZLIB) {
+		strm.zalloc = Z_NULL;
+		strm.zfree = Z_NULL;
+		strm.opaque = Z_NULL;
+		strm.avail_in = async->bufsize;
+		strm.next_in = async->buffer;
+		strm.avail_out = 0;
+		strm.next_out = Z_NULL;
+		ret = inflateInit(&strm);
+		if (ret != Z_OK) {
+			error("failed to initialize decompress parameters: %d",
+				ret);
+			return ret;
+		}
 	}
+	while (buf_offset < async->bufsize) {
+		bool compress_end = false;
+		int read_size = min_t(u64, async->bufsize - buf_offset,
+				      bufsize);
 
-	while (1) {
-		u64 bytenr, physical_dup;
-		off_t offset = 0;
-		int err = 0;
-
-		pthread_mutex_lock(&mdres->mutex);
-		while (!mdres->nodesize || list_empty(&mdres->list)) {
-			if (mdres->done) {
-				pthread_mutex_unlock(&mdres->mutex);
-				goto out;
+		/* Read part */
+		if (compress_method == COMPRESS_ZLIB) {
+			if (strm.avail_out == 0) {
+				strm.avail_out = bufsize;
+				strm.next_out = buffer;
 			}
-			pthread_cond_wait(&mdres->cond, &mdres->mutex);
-		}
-		async = list_entry(mdres->list.next, struct async_work, list);
-		list_del_init(&async->list);
-
-		if (mdres->compress_method == COMPRESS_ZLIB) {
-			size = compress_size;
 			pthread_mutex_unlock(&mdres->mutex);
-			ret = uncompress(buffer, (unsigned long *)&size,
-					 async->buffer, async->bufsize);
+			ret = inflate(&strm, Z_NO_FLUSH);
 			pthread_mutex_lock(&mdres->mutex);
-			if (ret != Z_OK) {
-				error("decompression failed with %d", ret);
-				err = -EIO;
+			switch (ret) {
+			case Z_NEED_DICT:
+				ret = Z_DATA_ERROR;
+				__attribute__ ((fallthrough));
+			case Z_DATA_ERROR:
+			case Z_MEM_ERROR:
+				goto out;
+			}
+			if (ret == Z_STREAM_END) {
+				ret = 0;
+				compress_end = true;
 			}
-			outbuf = buffer;
+			out_len = bufsize - strm.avail_out;
 		} else {
-			outbuf = async->buffer;
-			size = async->bufsize;
+			/* No compress, read as many data as possible */
+			memcpy(buffer, async->buffer + buf_offset, read_size);
+
+			buf_offset += read_size;
+			out_len = read_size;
 		}
 
+		/* Fixup part */
 		if (!mdres->multi_devices) {
 			if (async->start == BTRFS_SUPER_INFO_OFFSET) {
-				memcpy(mdres->original_super, outbuf,
+				memcpy(mdres->original_super, buffer,
 				       BTRFS_SUPER_INFO_SIZE);
 				if (mdres->old_restore) {
-					update_super_old(outbuf);
+					update_super_old(buffer);
 				} else {
-					ret = update_super(mdres, outbuf);
-					if (ret)
-						err = ret;
+					ret = update_super(mdres, buffer);
+					if (ret < 0)
+						goto out;
 				}
 			} else if (!mdres->old_restore) {
-				ret = fixup_chunk_tree_block(mdres, async, outbuf, size);
+				ret = fixup_chunk_tree_block(mdres, async,
+							     buffer, out_len);
 				if (ret)
-					err = ret;
+					goto out;
 			}
 		}
 
+		/* Write part */
 		if (!mdres->fixup_offset) {
+			int size = out_len;
+			off_t offset = 0;
+
 			while (size) {
+				u64 logical = async->start + out_offset + offset;
 				u64 chunk_size = size;
-				physical_dup = 0;
+				u64 physical_dup = 0;
+				u64 bytenr;
+
 				if (!mdres->multi_devices && !mdres->old_restore)
 					bytenr = logical_to_physical(mdres,
-						     async->start + offset,
-						     &chunk_size,
-						     &physical_dup);
+							logical, &chunk_size,
+							&physical_dup);
 				else
-					bytenr = async->start + offset;
+					bytenr = logical;
 
-				ret = pwrite64(outfd, outbuf+offset, chunk_size,
-					       bytenr);
+				ret = pwrite64(outfd, buffer + offset, chunk_size, bytenr);
 				if (ret != chunk_size)
-					goto error;
+					goto write_error;
 
 				if (physical_dup)
-					ret = pwrite64(outfd, outbuf+offset,
-						       chunk_size,
-						       physical_dup);
+					ret = pwrite64(outfd, buffer + offset,
+						       chunk_size, physical_dup);
 				if (ret != chunk_size)
-					goto error;
+					goto write_error;
 
 				size -= chunk_size;
 				offset += chunk_size;
 				continue;
-
-error:
-				if (ret < 0) {
-					error("unable to write to device: %m");
-					err = errno;
-				} else {
-					error("short write");
-					err = -EIO;
-				}
 			}
 		} else if (async->start != BTRFS_SUPER_INFO_OFFSET) {
-			ret = write_data_to_disk(mdres->info, outbuf, async->start, size, 0);
+			ret = write_data_to_disk(mdres->info, buffer,
+						 async->start, out_len, 0);
 			if (ret) {
 				error("failed to write data");
 				exit(1);
 			}
 		}
 
-
 		/* backup super blocks are already there at fixup_offset stage */
-		if (!mdres->multi_devices && async->start == BTRFS_SUPER_INFO_OFFSET)
-			write_backup_supers(outfd, outbuf);
+		if (async->start == BTRFS_SUPER_INFO_OFFSET &&
+		    !mdres->multi_devices)
+			write_backup_supers(outfd, buffer);
+		out_offset += out_len;
+		if (compress_end) {
+			inflateEnd(&strm);
+			break;
+		}
+	}
+	return ret;
+
+write_error:
+	if (ret < 0) {
+		error("unable to write to device: %m");
+		ret = -errno;
+	} else {
+		error("short write");
+		ret = -EIO;
+	}
+out:
+	if (compress_method == COMPRESS_ZLIB)
+		inflateEnd(&strm);
+	return ret;
+}
+
+static void *restore_worker(void *data)
+{
+	struct mdrestore_struct *mdres = (struct mdrestore_struct *)data;
+	struct async_work *async;
+	u8 *buffer;
+	int ret;
+	int buffer_size = SZ_512K;
+
+	buffer = malloc(buffer_size);
+	if (!buffer) {
+		error("not enough memory for restore worker buffer");
+		pthread_mutex_lock(&mdres->mutex);
+		if (!mdres->error)
+			mdres->error = -ENOMEM;
+		pthread_mutex_unlock(&mdres->mutex);
+		pthread_exit(NULL);
+	}
+
+	while (1) {
+		pthread_mutex_lock(&mdres->mutex);
+		while (!mdres->nodesize || list_empty(&mdres->list)) {
+			if (mdres->done) {
+				pthread_mutex_unlock(&mdres->mutex);
+				goto out;
+			}
+			pthread_cond_wait(&mdres->cond, &mdres->mutex);
+		}
+		async = list_entry(mdres->list.next, struct async_work, list);
+		list_del_init(&async->list);
 
-		if (err && !mdres->error)
-			mdres->error = err;
+		ret = restore_one_work(mdres, async, buffer, buffer_size);
+		if (ret < 0) {
+			mdres->error = ret;
+			pthread_mutex_unlock(&mdres->mutex);
+			goto out;
+		}
 		mdres->num_items--;
 		pthread_mutex_unlock(&mdres->mutex);
 
-- 
2.32.0

[PATCH v7 4/4] btrfs-progs: image: fix restored image size misalignment

[Qu Wenruo]

[BUG]
There is a small device size misalignment between the super block device
size and the device extent size:
total_bytes             10737418240 	<<<
bytes_used              15097856
dev_item.total_bytes    10737418240
dev_item.bytes_used     1094713344

        item 0 key (DEV_ITEMS DEV_ITEM 1) itemoff 16185 itemsize 98
                devid 1 total_bytes 1095761920 bytes_used 1094713344
				    ^^^^^^^^^^

[CAUSE]
In fixup_device_size(), we only reset superblock device item size, which
will be overwritten in write_dev_supers() using
btrfs_device::total_bytes.

And it doesn't touch btrfs_superblock::total_bytes either.

[FIX]
So fix the small mismatch by also resetting btrfs_device::total_bytes,
btrfs_device::bytes_used and btrfs_superblock::total_bytes.

Thankfully since commit 73dd4e3c87c9 ("btrfs-progs: image: Don't modify
the chunk and device tree if the source dump is single device") single
device dump won't have such problem, but it's still worthy for
multi-device dump.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 image/main.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/image/main.c b/image/main.c
index c622c544b5d3..bf4c62dafbaa 100644
--- a/image/main.c
+++ b/image/main.c
@@ -2377,6 +2377,7 @@ static int fixup_device_size(struct btrfs_trans_handle *trans,
 	struct btrfs_fs_info *fs_info = trans->fs_info;
 	struct btrfs_dev_item *dev_item;
 	struct btrfs_dev_extent *dev_ext;
+	struct btrfs_device *dev;
 	struct btrfs_path path;
 	struct extent_buffer *leaf;
 	struct btrfs_root *root = fs_info->chunk_root;
@@ -2395,6 +2396,8 @@ static int fixup_device_size(struct btrfs_trans_handle *trans,
 	key.type = BTRFS_DEV_EXTENT_KEY;
 	key.offset = (u64)-1;
 
+	dev = list_first_entry(&fs_info->fs_devices->devices,
+				struct btrfs_device, dev_list);
 	ret = btrfs_search_slot(NULL, fs_info->dev_root, &key, &path, 0, 0);
 	if (ret < 0) {
 		errno = -ret;
@@ -2428,6 +2431,9 @@ static int fixup_device_size(struct btrfs_trans_handle *trans,
 
 	btrfs_set_stack_device_total_bytes(dev_item, dev_size);
 	btrfs_set_stack_device_bytes_used(dev_item, mdres->alloced_chunks);
+	dev->total_bytes = dev_size;
+	dev->bytes_used = mdres->alloced_chunks;
+	btrfs_set_super_total_bytes(fs_info->super_copy, dev_size);
 	ret = fstat(out_fd, &buf);
 	if (ret < 0) {
 		error("failed to stat result image: %m");
-- 
2.32.0

Re: [PATCH v7 0/4] btrfs-progs: image: new data dump feature

[David Sterba]

On Tue, Aug 24, 2021 at 03:41:04PM +0800, Qu Wenruo wrote:
> v7:
> - Rebased to latest devel branch
>   No conflicts at all.
> 
> - Hide the data dump feature behind the experimental features
>   Now to make "btrfs-image -d" work, one must enable experimental
>   features, or "btrfs-image -d" will only output an error message.
> 
>   And if experimental features are not enabled, the new header format
>   will also be disabled, so that btrfs-image can't detect the new format
>   either.
> 
>   Although the "-d" option is still enabled for the non-experimental
>   build.

Thanks.  I've created issue #394 for tracking, with label 'experimental'
so we know what's in progress. If there are separate tasks related to
that then they could be tracked in other issues and referenced from that
one.