[PATCH] btrfs-progs: inspect-internal: add option '-k u64,u8,u64' of dump-tree

[PATCH] btrfs-progs: inspect-internal: add option '-k u64,u8,u64' of dump-tree

[Su Yue]

For big filesystems, there are many items in trees(extent tree
specially).
For example, to dump one extent, we usually dump extent tree then pipe
result to grep. The time-consuming part is that dump tree traverses
items. And it eats cpu and memory too.

This patch introduces an option '-k u64,u8,u64' for users(developer more
likely) to appoint a specific key to search and dump, then the path
from root node down the leaf will be dumped.
The search of the key costs most time of this way.

Signed-off-by: Su Yue <suy.fnst@cn.fujitsu.com>
---
In my experiment, not usual case though.
Image was provided by Chris Murphy, thanks.

#btrfs filesystem df /mnt
Data, single: total=767.00GiB, used=766.58GiB
System, DUP: total=32.00MiB, used=112.00KiB
Metadata, DUP: total=5.50GiB, used=4.69GiB
Metadata, single: total=16.00MiB, used=0.00B
GlobalReserve, single: total=512.00MiB, used=0.00B

Before:
#time bash -c 'btrfs inspect-internal dump-tree -t 2 ~/test/test.img | grep "1295194308608" >> /dev/null'
real    0m34.024s
user    0m3.269s
sys     0m4.047s

Patched and use -k:
#time bash -c './btrfs inspect-internal dump-tree -t 2  -k 1295194308608,0,0 ~/test/test.img >> /dev/null'

real    0m1.408s
user    0m0.006s
sys     0m0.014s

The new way is 34 times faster than 'grep' way, uses less memory and
cpu, and it prints path useful for debug.

---
 cmds-inspect-dump-tree.c |  54 +++++++++++++++++--
 print-tree.c             | 112 +++++++++++++++++++++++++++++++++++++++
 print-tree.h             |   2 +
 3 files changed, 163 insertions(+), 5 deletions(-)

diff --git a/cmds-inspect-dump-tree.c b/cmds-inspect-dump-tree.c
index c8acd55a0c3a..2a1a40c8270d 100644
--- a/cmds-inspect-dump-tree.c
+++ b/cmds-inspect-dump-tree.c
@@ -184,6 +184,21 @@ static u64 treeid_from_string(const char *str, const char **end)
 	return id;
 }
 
+static int parse_key(struct btrfs_key *key)
+{
+
+	int ret = sscanf(optarg, "%llu,%hhu,%llu", &key->objectid,
+			 &key->type, &key->offset);
+	if (ret != 3) {
+		error("error parsing key '%s'\n", optarg);
+		ret = -EINVAL;
+	} else {
+		ret = 0;
+	}
+
+	return ret;
+}
+
 const char * const cmd_inspect_dump_tree_usage[] = {
 	"btrfs inspect-internal dump-tree [options] device",
 	"Dump tree structures from a given device",
@@ -199,6 +214,7 @@ const char * const cmd_inspect_dump_tree_usage[] = {
 	"-u|--uuid              print only the uuid tree",
 	"-b|--block <block_num> print info from the specified block only",
 	"-t|--tree <tree_id>    print only tree with the given id (string or number)",
+	"-k|--key <u64,u8,u64>  search the specific key then print path, must with -t",
 	"--follow               use with -b, to show all children tree blocks of <block_num>",
 	NULL
 };
@@ -224,8 +240,10 @@ int cmd_inspect_dump_tree(int argc, char **argv)
 	unsigned open_ctree_flags;
 	u64 block_only = 0;
 	struct btrfs_root *tree_root_scan;
+	struct btrfs_key spec_key = { 0 };
 	u64 tree_id = 0;
 	bool follow = false;
+	bool is_key_spec = false;
 
 	/*
 	 * For debug-tree, we care nothing about extent tree (it's just backref
@@ -248,10 +266,11 @@ int cmd_inspect_dump_tree(int argc, char **argv)
 			{ "block", required_argument, NULL, 'b'},
 			{ "tree", required_argument, NULL, 't'},
 			{ "follow", no_argument, NULL, GETOPT_VAL_FOLLOW },
+			{"key", required_argument, NULL, 'k'},
 			{ NULL, 0, NULL, 0 }
 		};
 
-		c = getopt_long(argc, argv, "deb:rRut:", long_options, NULL);
+		c = getopt_long(argc, argv, "deb:rRut:k:", long_options, NULL);
 		if (c < 0)
 			break;
 		switch (c) {
@@ -300,6 +319,12 @@ int cmd_inspect_dump_tree(int argc, char **argv)
 			}
 			break;
 			}
+		case 'k':
+			ret = parse_key(&spec_key);
+			if (ret)
+				exit(1);
+			is_key_spec = true;
+			break;
 		case GETOPT_VAL_FOLLOW:
 			follow = true;
 			break;
@@ -308,6 +333,9 @@ int cmd_inspect_dump_tree(int argc, char **argv)
 		}
 	}
 
+	if (!tree_id && is_key_spec)
+		usage(cmd_inspect_dump_tree_usage);
+
 	if (check_argc_exact(argc - optind, 1))
 		usage(cmd_inspect_dump_tree_usage);
 
@@ -398,7 +426,11 @@ again:
 			goto close_root;
 		}
 		printf("root tree\n");
-		btrfs_print_tree(info->tree_root->node, 1);
+		if (is_key_spec)
+			btrfs_print_spec_key(info, BTRFS_ROOT_TREE_OBJECTID,
+					     &spec_key);
+		else
+			btrfs_print_tree(info->tree_root->node, 1);
 		goto close_root;
 	}
 
@@ -408,7 +440,11 @@ again:
 			goto close_root;
 		}
 		printf("chunk tree\n");
-		btrfs_print_tree(info->chunk_root->node, 1);
+		if (is_key_spec)
+			btrfs_print_spec_key(info, BTRFS_CHUNK_TREE_OBJECTID,
+					     &spec_key);
+		else
+			btrfs_print_tree(info->chunk_root->node, 1);
 		goto close_root;
 	}
 
@@ -418,7 +454,11 @@ again:
 			goto close_root;
 		}
 		printf("log root tree\n");
-		btrfs_print_tree(info->log_root_tree->node, 1);
+		if (is_key_spec)
+			btrfs_print_spec_key(info, BTRFS_TREE_LOG_OBJECTID,
+					     &spec_key);
+		else
+			btrfs_print_tree(info->log_root_tree->node, 1);
 		goto close_root;
 	}
 
@@ -564,7 +604,11 @@ again:
 					       btrfs_header_level(buf));
 				} else {
 					printf(" \n");
-					btrfs_print_tree(buf, 1);
+					if (is_key_spec)
+						btrfs_print_spec_key(info,
+						     found_key.objectid, &spec_key);
+					else
+						btrfs_print_tree(buf, 1);
 				}
 			}
 			free_extent_buffer(buf);
diff --git a/print-tree.c b/print-tree.c
index a09ecfbb28f0..f3a19fed8591 100644
--- a/print-tree.c
+++ b/print-tree.c
@@ -1459,3 +1459,115 @@ void btrfs_print_tree(struct extent_buffer *eb, int follow)
 
 	return;
 }
+
+void btrfs_print_spec_key(struct btrfs_fs_info *fs_info, u64 root_objectid,
+			  struct btrfs_key *skey)
+{
+	int i;
+	u32 nr;
+	u32 ptr_num;
+	int ret;
+	int level;
+	struct btrfs_root *root;
+	struct btrfs_disk_key disk_key;
+	struct btrfs_key key;
+	struct extent_buffer *next;
+	struct extent_buffer *eb;
+	struct btrfs_path path;
+
+	key.objectid = root_objectid;
+	key.type = BTRFS_ROOT_ITEM_KEY;
+	key.offset = (u64)-1;
+
+	if (key.objectid == BTRFS_TREE_RELOC_OBJECTID)
+		root = btrfs_read_fs_root_no_cache(fs_info, &key);
+	else
+		root = btrfs_read_fs_root(fs_info, &key);
+
+	if (IS_ERR(root) || !root) {
+		error("failed to read tree: %lld", key.objectid);
+		return;
+	}
+
+	btrfs_init_path(&path);
+	ret = btrfs_search_slot(NULL, root, skey, &path, 0, 0);
+	if (ret < 0) {
+		error("error search the key [%llu, %u, %llu] in root %llu",
+		      skey->objectid, skey->type, skey->offset, root->objectid);
+		goto out;
+	}
+
+	if (ret > 0) {
+		if (path.slots[0] > btrfs_header_nritems(path.nodes[0])) {
+			ret = btrfs_next_item(root, &path);
+			if (ret) {
+				error(
+	"error search the key [%llu, %u, %llu] in root %llu, no next key",
+					skey->objectid, skey->type,
+					skey->offset, root->objectid);
+				goto out;
+			}
+		}
+
+		btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
+		printf("next to search key is [%llu, %u, %llu]\n",
+		       key.objectid, key.type, key.offset);
+	}
+
+	level = btrfs_header_level(root->node);
+	for (; level >= 0 ; --level) {
+		eb = path.nodes[level];
+		next = path.nodes[level - 1];
+		nr = btrfs_header_nritems(eb);
+		if (btrfs_is_leaf(eb)) {
+			btrfs_print_leaf(eb);
+			goto out;
+		}
+
+		/* We are crossing eb boundary, this node must be corrupted */
+		if (nr > BTRFS_NODEPTRS_PER_EXTENT_BUFFER(eb))
+			warning(
+		"node nr_items corrupted, has %u limit %u, continue anyway",
+				nr, BTRFS_NODEPTRS_PER_EXTENT_BUFFER(eb));
+		printf(
+		"node %llu level %d items %d free %u generation %llu owner ",
+		       (unsigned long long)eb->start,
+		       btrfs_header_level(eb), nr,
+		       (u32)BTRFS_NODEPTRS_PER_EXTENT_BUFFER(eb) - nr,
+		       (unsigned long long)btrfs_header_generation(eb));
+		print_objectid(stdout, btrfs_header_owner(eb), 0);
+		printf("\n");
+		print_uuids(eb);
+		fflush(stdout);
+		ptr_num = BTRFS_NODEPTRS_PER_EXTENT_BUFFER(eb);
+		for (i = 0; i < nr && i < ptr_num; i++) {
+			u64 blocknr = btrfs_node_blockptr(eb, i);
+
+			btrfs_node_key(eb, &disk_key, i);
+			btrfs_disk_key_to_cpu(&key, &disk_key);
+			printf("\t");
+			btrfs_print_key(&disk_key);
+			printf(" block %llu (%llu) gen %llu\n",
+			       (unsigned long long)blocknr,
+			       (unsigned long long)blocknr / eb->len,
+			       (unsigned long long)btrfs_node_ptr_generation(eb, i));
+			fflush(stdout);
+		}
+
+		if (btrfs_header_level(next) != btrfs_header_level(eb) - 1) {
+			warning(
+				"eb corrupted: parent bytenr %llu slot %d level %d child bytenr %llu level has %d expect %d, skipping the slot",
+				btrfs_header_bytenr(eb), i,
+				btrfs_header_level(eb),
+				btrfs_header_bytenr(next),
+				btrfs_header_level(next),
+				btrfs_header_level(eb) - 1);
+			continue;
+		}
+	}
+
+out:
+	if (root_objectid == BTRFS_TREE_RELOC_OBJECTID)
+		btrfs_free_fs_root(root);
+	btrfs_release_path(&path);
+}
diff --git a/print-tree.h b/print-tree.h
index 62667d7f6195..94f231875a6c 100644
--- a/print-tree.h
+++ b/print-tree.h
@@ -26,4 +26,6 @@ void print_chunk_item(struct extent_buffer *eb, struct btrfs_chunk *chunk);
 void print_extent_item(struct extent_buffer *eb, int slot, int metadata);
 void print_objectid(FILE *stream, u64 objectid, u8 type);
 void print_key_type(FILE *stream, u64 objectid, u8 type);
+void btrfs_print_spec_key(struct btrfs_fs_info *info, u64 root_objectid,
+			  struct btrfs_key *key);
 #endif
-- 
2.17.1

Re: [PATCH] btrfs-progs: inspect-internal: add option '-k u64,u8,u64' of dump-tree

[Qu Wenruo]

On 2018年07月16日 13:55, Su Yue wrote:
> For big filesystems, there are many items in trees(extent tree
> specially).
> For example, to dump one extent, we usually dump extent tree then pipe
> result to grep. The time-consuming part is that dump tree traverses
> items. And it eats cpu and memory too.
> 
> This patch introduces an option '-k u64,u8,u64' for users(developer more
> likely) to appoint a specific key to search and dump, then the path
> from root node down the leaf will be dumped.
> The search of the key costs most time of this way.

Indeed a pretty useful debug oriented feature.

> 
> Signed-off-by: Su Yue <suy.fnst@cn.fujitsu.com>
> ---
> In my experiment, not usual case though.
> Image was provided by Chris Murphy, thanks.
> 
> #btrfs filesystem df /mnt
> Data, single: total=767.00GiB, used=766.58GiB
> System, DUP: total=32.00MiB, used=112.00KiB
> Metadata, DUP: total=5.50GiB, used=4.69GiB
> Metadata, single: total=16.00MiB, used=0.00B
> GlobalReserve, single: total=512.00MiB, used=0.00B
> 
> Before:
> #time bash -c 'btrfs inspect-internal dump-tree -t 2 ~/test/test.img | grep "1295194308608" >> /dev/null'
> real    0m34.024s
> user    0m3.269s
> sys     0m4.047s
> 
> Patched and use -k:
> #time bash -c './btrfs inspect-internal dump-tree -t 2  -k 1295194308608,0,0 ~/test/test.img >> /dev/null'
> 
> real    0m1.408s
> user    0m0.006s
> sys     0m0.014s
> 
> The new way is 34 times faster than 'grep' way, uses less memory and
> cpu, and it prints path useful for debug.
> 
> ---
>  cmds-inspect-dump-tree.c |  54 +++++++++++++++++--
>  print-tree.c             | 112 +++++++++++++++++++++++++++++++++++++++
>  print-tree.h             |   2 +
>  3 files changed, 163 insertions(+), 5 deletions(-)
> 
> diff --git a/cmds-inspect-dump-tree.c b/cmds-inspect-dump-tree.c
> index c8acd55a0c3a..2a1a40c8270d 100644
> --- a/cmds-inspect-dump-tree.c
> +++ b/cmds-inspect-dump-tree.c
> @@ -184,6 +184,21 @@ static u64 treeid_from_string(const char *str, const char **end)
>  	return id;
>  }
>  
> +static int parse_key(struct btrfs_key *key)
> +{
> +
> +	int ret = sscanf(optarg, "%llu,%hhu,%llu", &key->objectid,
> +			 &key->type, &key->offset);
> +	if (ret != 3) {
> +		error("error parsing key '%s'\n", optarg);
> +		ret = -EINVAL;
> +	} else {
> +		ret = 0;
> +	}
> +
> +	return ret;
> +}
> +
>  const char * const cmd_inspect_dump_tree_usage[] = {
>  	"btrfs inspect-internal dump-tree [options] device",
>  	"Dump tree structures from a given device",
> @@ -199,6 +214,7 @@ const char * const cmd_inspect_dump_tree_usage[] = {
>  	"-u|--uuid              print only the uuid tree",
>  	"-b|--block <block_num> print info from the specified block only",
>  	"-t|--tree <tree_id>    print only tree with the given id (string or number)",
> +	"-k|--key <u64,u8,u64>  search the specific key then print path, must with -t",

Shouldn't it conflict with -b and -r?

>  	"--follow               use with -b, to show all children tree blocks of <block_num>",
>  	NULL
>  };
> @@ -224,8 +240,10 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>  	unsigned open_ctree_flags;
>  	u64 block_only = 0;
>  	struct btrfs_root *tree_root_scan;
> +	struct btrfs_key spec_key = { 0 };
>  	u64 tree_id = 0;
>  	bool follow = false;
> +	bool is_key_spec = false;

What about @key_set? @is_key_spec looks a little strange here.

>  
>  	/*
>  	 * For debug-tree, we care nothing about extent tree (it's just backref
> @@ -248,10 +266,11 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>  			{ "block", required_argument, NULL, 'b'},
>  			{ "tree", required_argument, NULL, 't'},
>  			{ "follow", no_argument, NULL, GETOPT_VAL_FOLLOW },
> +			{"key", required_argument, NULL, 'k'},

Small alignment mismatch, missing a space before "key".

>  			{ NULL, 0, NULL, 0 }
>  		};
>  
> -		c = getopt_long(argc, argv, "deb:rRut:", long_options, NULL);
> +		c = getopt_long(argc, argv, "deb:rRut:k:", long_options, NULL);
>  		if (c < 0)
>  			break;
>  		switch (c) {
> @@ -300,6 +319,12 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>  			}
>  			break;
>  			}
> +		case 'k':
> +			ret = parse_key(&spec_key);
> +			if (ret)
> +				exit(1);
> +			is_key_spec = true;
> +			break;
>  		case GETOPT_VAL_FOLLOW:
>  			follow = true;
>  			break;
> @@ -308,6 +333,9 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>  		}
>  	}
>  
> +	if (!tree_id && is_key_spec)
> +		usage(cmd_inspect_dump_tree_usage);
> +
>  	if (check_argc_exact(argc - optind, 1))
>  		usage(cmd_inspect_dump_tree_usage);
>  
> @@ -398,7 +426,11 @@ again:
>  			goto close_root;
>  		}
>  		printf("root tree\n");
> -		btrfs_print_tree(info->tree_root->node, 1);
> +		if (is_key_spec)
> +			btrfs_print_spec_key(info, BTRFS_ROOT_TREE_OBJECTID,
> +					     &spec_key);
> +		else
> +			btrfs_print_tree(info->tree_root->node, 1);
>  		goto close_root;
>  	}
>  
> @@ -408,7 +440,11 @@ again:
>  			goto close_root;
>  		}
>  		printf("chunk tree\n");
> -		btrfs_print_tree(info->chunk_root->node, 1);
> +		if (is_key_spec)
> +			btrfs_print_spec_key(info, BTRFS_CHUNK_TREE_OBJECTID,
> +					     &spec_key);
> +		else
> +			btrfs_print_tree(info->chunk_root->node, 1);
>  		goto close_root;
>  	}
>  

I really don't thing we need to put btrfS_print_spec_key() here.

It's in fact a special case, no need to nest it into the loop.
Not to mention it appears 3 times in the main loop.

> @@ -418,7 +454,11 @@ again:
>  			goto close_root;
>  		}
>  		printf("log root tree\n");
> -		btrfs_print_tree(info->log_root_tree->node, 1);
> +		if (is_key_spec)
> +			btrfs_print_spec_key(info, BTRFS_TREE_LOG_OBJECTID,
> +					     &spec_key);
> +		else
> +			btrfs_print_tree(info->log_root_tree->node, 1);
>  		goto close_root;
>  	}
>  
> @@ -564,7 +604,11 @@ again:
>  					       btrfs_header_level(buf));
>  				} else {
>  					printf(" \n");
> -					btrfs_print_tree(buf, 1);
> +					if (is_key_spec)
> +						btrfs_print_spec_key(info,
> +						     found_key.objectid, &spec_key);
> +					else
> +						btrfs_print_tree(buf, 1);
>  				}
>  			}
>  			free_extent_buffer(buf);
> diff --git a/print-tree.c b/print-tree.c
> index a09ecfbb28f0..f3a19fed8591 100644
> --- a/print-tree.c
> +++ b/print-tree.c
> @@ -1459,3 +1459,115 @@ void btrfs_print_tree(struct extent_buffer *eb, int follow)
>  
>  	return;
>  }
> +
> +void btrfs_print_spec_key(struct btrfs_fs_info *fs_info, u64 root_objectid,
> +			  struct btrfs_key *skey)
> +{
> +	int i;
> +	u32 nr;
> +	u32 ptr_num;
> +	int ret;
> +	int level;
> +	struct btrfs_root *root;
> +	struct btrfs_disk_key disk_key;
> +	struct btrfs_key key;
> +	struct extent_buffer *next;
> +	struct extent_buffer *eb;
> +	struct btrfs_path path;
> +
> +	key.objectid = root_objectid;
> +	key.type = BTRFS_ROOT_ITEM_KEY;
> +	key.offset = (u64)-1;
> +
> +	if (key.objectid == BTRFS_TREE_RELOC_OBJECTID)
> +		root = btrfs_read_fs_root_no_cache(fs_info, &key);
> +	else
> +		root = btrfs_read_fs_root(fs_info, &key);
> +
> +	if (IS_ERR(root) || !root) {
> +		error("failed to read tree: %lld", key.objectid);
> +		return;
> +	}
> +
> +	btrfs_init_path(&path);
> +	ret = btrfs_search_slot(NULL, root, skey, &path, 0, 0);
> +	if (ret < 0) {
> +		error("error search the key [%llu, %u, %llu] in root %llu",
> +		      skey->objectid, skey->type, skey->offset, root->objectid);
> +		goto out;
> +	}
> +
> +	if (ret > 0) {
> +		if (path.slots[0] > btrfs_header_nritems(path.nodes[0])) {
> +			ret = btrfs_next_item(root, &path);
> +			if (ret) {
> +				error(
> +	"error search the key [%llu, %u, %llu] in root %llu, no next key",
> +					skey->objectid, skey->type,
> +					skey->offset, root->objectid);
> +				goto out;
> +			}
> +		}
> +
> +		btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
> +		printf("next to search key is [%llu, %u, %llu]\n",
> +		       key.objectid, key.type, key.offset);
> +	}
> +
> +	level = btrfs_header_level(root->node);
> +	for (; level >= 0 ; --level) {
> +		eb = path.nodes[level];
> +		next = path.nodes[level - 1];
> +		nr = btrfs_header_nritems(eb);

In fact, btrfs_print_tree() could replace all the following code.
Which should further shrink the code size.

Thanks,
Qu

> +		if (btrfs_is_leaf(eb)) {
> +			btrfs_print_leaf(eb);
> +			goto out;
> +		}
> +
> +		/* We are crossing eb boundary, this node must be corrupted */
> +		if (nr > BTRFS_NODEPTRS_PER_EXTENT_BUFFER(eb))
> +			warning(
> +		"node nr_items corrupted, has %u limit %u, continue anyway",
> +				nr, BTRFS_NODEPTRS_PER_EXTENT_BUFFER(eb));
> +		printf(
> +		"node %llu level %d items %d free %u generation %llu owner ",
> +		       (unsigned long long)eb->start,
> +		       btrfs_header_level(eb), nr,
> +		       (u32)BTRFS_NODEPTRS_PER_EXTENT_BUFFER(eb) - nr,
> +		       (unsigned long long)btrfs_header_generation(eb));
> +		print_objectid(stdout, btrfs_header_owner(eb), 0);
> +		printf("\n");
> +		print_uuids(eb);
> +		fflush(stdout);
> +		ptr_num = BTRFS_NODEPTRS_PER_EXTENT_BUFFER(eb);
> +		for (i = 0; i < nr && i < ptr_num; i++) {
> +			u64 blocknr = btrfs_node_blockptr(eb, i);
> +
> +			btrfs_node_key(eb, &disk_key, i);
> +			btrfs_disk_key_to_cpu(&key, &disk_key);
> +			printf("\t");
> +			btrfs_print_key(&disk_key);
> +			printf(" block %llu (%llu) gen %llu\n",
> +			       (unsigned long long)blocknr,
> +			       (unsigned long long)blocknr / eb->len,
> +			       (unsigned long long)btrfs_node_ptr_generation(eb, i));
> +			fflush(stdout);
> +		}
> +
> +		if (btrfs_header_level(next) != btrfs_header_level(eb) - 1) {
> +			warning(
> +				"eb corrupted: parent bytenr %llu slot %d level %d child bytenr %llu level has %d expect %d, skipping the slot",
> +				btrfs_header_bytenr(eb), i,
> +				btrfs_header_level(eb),
> +				btrfs_header_bytenr(next),
> +				btrfs_header_level(next),
> +				btrfs_header_level(eb) - 1);
> +			continue;
> +		}
> +	}
> +
> +out:
> +	if (root_objectid == BTRFS_TREE_RELOC_OBJECTID)
> +		btrfs_free_fs_root(root);
> +	btrfs_release_path(&path);
> +}
> diff --git a/print-tree.h b/print-tree.h
> index 62667d7f6195..94f231875a6c 100644
> --- a/print-tree.h
> +++ b/print-tree.h
> @@ -26,4 +26,6 @@ void print_chunk_item(struct extent_buffer *eb, struct btrfs_chunk *chunk);
>  void print_extent_item(struct extent_buffer *eb, int slot, int metadata);
>  void print_objectid(FILE *stream, u64 objectid, u8 type);
>  void print_key_type(FILE *stream, u64 objectid, u8 type);
> +void btrfs_print_spec_key(struct btrfs_fs_info *info, u64 root_objectid,
> +			  struct btrfs_key *key);
>  #endif
> 

Re: [PATCH] btrfs-progs: inspect-internal: add option '-k u64,u8,u64' of dump-tree

[Su Yue]

On 07/16/2018 03:45 PM, Qu Wenruo wrote:
> 
> 
> On 2018年07月16日 13:55, Su Yue wrote:
>> For big filesystems, there are many items in trees(extent tree
>> specially).
>> For example, to dump one extent, we usually dump extent tree then pipe
>> result to grep. The time-consuming part is that dump tree traverses
>> items. And it eats cpu and memory too.
>>
>> This patch introduces an option '-k u64,u8,u64' for users(developer more
>> likely) to appoint a specific key to search and dump, then the path
>> from root node down the leaf will be dumped.
>> The search of the key costs most time of this way.
> 
> Indeed a pretty useful debug oriented feature.
> 
>>
>> Signed-off-by: Su Yue <suy.fnst@cn.fujitsu.com>
>> ---
>> In my experiment, not usual case though.
>> Image was provided by Chris Murphy, thanks.
>>
>> #btrfs filesystem df /mnt
>> Data, single: total=767.00GiB, used=766.58GiB
>> System, DUP: total=32.00MiB, used=112.00KiB
>> Metadata, DUP: total=5.50GiB, used=4.69GiB
>> Metadata, single: total=16.00MiB, used=0.00B
>> GlobalReserve, single: total=512.00MiB, used=0.00B
>>
>> Before:
>> #time bash -c 'btrfs inspect-internal dump-tree -t 2 ~/test/test.img | grep "1295194308608" >> /dev/null'
>> real    0m34.024s
>> user    0m3.269s
>> sys     0m4.047s
>>
>> Patched and use -k:
>> #time bash -c './btrfs inspect-internal dump-tree -t 2  -k 1295194308608,0,0 ~/test/test.img >> /dev/null'
>>
>> real    0m1.408s
>> user    0m0.006s
>> sys     0m0.014s
>>
>> The new way is 34 times faster than 'grep' way, uses less memory and
>> cpu, and it prints path useful for debug.
>>
>> ---
>>   cmds-inspect-dump-tree.c |  54 +++++++++++++++++--
>>   print-tree.c             | 112 +++++++++++++++++++++++++++++++++++++++
>>   print-tree.h             |   2 +
>>   3 files changed, 163 insertions(+), 5 deletions(-)
>>
>> diff --git a/cmds-inspect-dump-tree.c b/cmds-inspect-dump-tree.c
>> index c8acd55a0c3a..2a1a40c8270d 100644
>> --- a/cmds-inspect-dump-tree.c
>> +++ b/cmds-inspect-dump-tree.c
>> @@ -184,6 +184,21 @@ static u64 treeid_from_string(const char *str, const char **end)
>>   	return id;
>>   }
>>   
>> +static int parse_key(struct btrfs_key *key)
>> +{
>> +
>> +	int ret = sscanf(optarg, "%llu,%hhu,%llu", &key->objectid,
>> +			 &key->type, &key->offset);
>> +	if (ret != 3) {
>> +		error("error parsing key '%s'\n", optarg);
>> +		ret = -EINVAL;
>> +	} else {
>> +		ret = 0;
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>>   const char * const cmd_inspect_dump_tree_usage[] = {
>>   	"btrfs inspect-internal dump-tree [options] device",
>>   	"Dump tree structures from a given device",
>> @@ -199,6 +214,7 @@ const char * const cmd_inspect_dump_tree_usage[] = {
>>   	"-u|--uuid              print only the uuid tree",
>>   	"-b|--block <block_num> print info from the specified block only",
>>   	"-t|--tree <tree_id>    print only tree with the given id (string or number)",
>> +	"-k|--key <u64,u8,u64>  search the specific key then print path, must with -t",
> 
> Shouldn't it conflict with -b and -r?
> 
>>   	"--follow               use with -b, to show all children tree blocks of <block_num>",
>>   	NULL
>>   };
>> @@ -224,8 +240,10 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>>   	unsigned open_ctree_flags;
>>   	u64 block_only = 0;
>>   	struct btrfs_root *tree_root_scan;
>> +	struct btrfs_key spec_key = { 0 };
>>   	u64 tree_id = 0;
>>   	bool follow = false;
>> +	bool is_key_spec = false;
> 
> What about @key_set? @is_key_spec looks a little strange here.
> 
Ok, will call it is_spec_key_set in next version.

>>   
>>   	/*
>>   	 * For debug-tree, we care nothing about extent tree (it's just backref
>> @@ -248,10 +266,11 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>>   			{ "block", required_argument, NULL, 'b'},
>>   			{ "tree", required_argument, NULL, 't'},
>>   			{ "follow", no_argument, NULL, GETOPT_VAL_FOLLOW },
>> +			{"key", required_argument, NULL, 'k'},
> 
> Small alignment mismatch, missing a space before "key".
> 
>>   			{ NULL, 0, NULL, 0 }
>>   		};
>>   
>> -		c = getopt_long(argc, argv, "deb:rRut:", long_options, NULL);
>> +		c = getopt_long(argc, argv, "deb:rRut:k:", long_options, NULL);
>>   		if (c < 0)
>>   			break;
>>   		switch (c) {
>> @@ -300,6 +319,12 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>>   			}
>>   			break;
>>   			}
>> +		case 'k':
>> +			ret = parse_key(&spec_key);
>> +			if (ret)
>> +				exit(1);
>> +			is_key_spec = true;
>> +			break;
>>   		case GETOPT_VAL_FOLLOW:
>>   			follow = true;
>>   			break;
>> @@ -308,6 +333,9 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>>   		}
>>   	}
>>   
>> +	if (!tree_id && is_key_spec)
>> +		usage(cmd_inspect_dump_tree_usage);
>> +
>>   	if (check_argc_exact(argc - optind, 1))
>>   		usage(cmd_inspect_dump_tree_usage);
>>   
>> @@ -398,7 +426,11 @@ again:
>>   			goto close_root;
>>   		}
>>   		printf("root tree\n");
>> -		btrfs_print_tree(info->tree_root->node, 1);
>> +		if (is_key_spec)
>> +			btrfs_print_spec_key(info, BTRFS_ROOT_TREE_OBJECTID,
>> +					     &spec_key);
>> +		else
>> +			btrfs_print_tree(info->tree_root->node, 1);
>>   		goto close_root;
>>   	}
>>   
>> @@ -408,7 +440,11 @@ again:
>>   			goto close_root;
>>   		}
>>   		printf("chunk tree\n");
>> -		btrfs_print_tree(info->chunk_root->node, 1);
>> +		if (is_key_spec)
>> +			btrfs_print_spec_key(info, BTRFS_CHUNK_TREE_OBJECTID,
>> +					     &spec_key);
>> +		else
>> +			btrfs_print_tree(info->chunk_root->node, 1);
>>   		goto close_root;
>>   	}
>>   
> 
> I really don't thing we need to put btrfS_print_spec_key() here.
> 
> It's in fact a special case, no need to nest it into the loop.
> Not to mention it appears 3 times in the main loop.
> 
Not understood what you mean.

>> @@ -418,7 +454,11 @@ again:
>>   			goto close_root;
>>   		}
>>   		printf("log root tree\n");
>> -		btrfs_print_tree(info->log_root_tree->node, 1);
>> +		if (is_key_spec)
>> +			btrfs_print_spec_key(info, BTRFS_TREE_LOG_OBJECTID,
>> +					     &spec_key);
>> +		else
>> +			btrfs_print_tree(info->log_root_tree->node, 1);
>>   		goto close_root;
>>   	}
>>   
>> @@ -564,7 +604,11 @@ again:
>>   					       btrfs_header_level(buf));
>>   				} else {
>>   					printf(" \n");
>> -					btrfs_print_tree(buf, 1);
>> +					if (is_key_spec)
>> +						btrfs_print_spec_key(info,
>> +						     found_key.objectid, &spec_key);
>> +					else
>> +						btrfs_print_tree(buf, 1);
>>   				}
>>   			}
>>   			free_extent_buffer(buf);
>> diff --git a/print-tree.c b/print-tree.c
>> index a09ecfbb28f0..f3a19fed8591 100644
>> --- a/print-tree.c
>> +++ b/print-tree.c
>> @@ -1459,3 +1459,115 @@ void btrfs_print_tree(struct extent_buffer *eb, int follow)
>>   
>>   	return;
>>   }
>> +
>> +void btrfs_print_spec_key(struct btrfs_fs_info *fs_info, u64 root_objectid,
>> +			  struct btrfs_key *skey)
>> +{
>> +	int i;
>> +	u32 nr;
>> +	u32 ptr_num;
>> +	int ret;
>> +	int level;
>> +	struct btrfs_root *root;
>> +	struct btrfs_disk_key disk_key;
>> +	struct btrfs_key key;
>> +	struct extent_buffer *next;
>> +	struct extent_buffer *eb;
>> +	struct btrfs_path path;
>> +
>> +	key.objectid = root_objectid;
>> +	key.type = BTRFS_ROOT_ITEM_KEY;
>> +	key.offset = (u64)-1;
>> +
>> +	if (key.objectid == BTRFS_TREE_RELOC_OBJECTID)
>> +		root = btrfs_read_fs_root_no_cache(fs_info, &key);
>> +	else
>> +		root = btrfs_read_fs_root(fs_info, &key);
>> +
>> +	if (IS_ERR(root) || !root) {
>> +		error("failed to read tree: %lld", key.objectid);
>> +		return;
>> +	}
>> +
>> +	btrfs_init_path(&path);
>> +	ret = btrfs_search_slot(NULL, root, skey, &path, 0, 0);
>> +	if (ret < 0) {
>> +		error("error search the key [%llu, %u, %llu] in root %llu",
>> +		      skey->objectid, skey->type, skey->offset, root->objectid);
>> +		goto out;
>> +	}
>> +
>> +	if (ret > 0) {
>> +		if (path.slots[0] > btrfs_header_nritems(path.nodes[0])) {
>> +			ret = btrfs_next_item(root, &path);
>> +			if (ret) {
>> +				error(
>> +	"error search the key [%llu, %u, %llu] in root %llu, no next key",
>> +					skey->objectid, skey->type,
>> +					skey->offset, root->objectid);
>> +				goto out;
>> +			}
>> +		}
>> +
>> +		btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
>> +		printf("next to search key is [%llu, %u, %llu]\n",
>> +		       key.objectid, key.type, key.offset);
>> +	}
>> +
>> +	level = btrfs_header_level(root->node);
>> +	for (; level >= 0 ; --level) {
>> +		eb = path.nodes[level];
>> +		next = path.nodes[level - 1];
>> +		nr = btrfs_header_nritems(eb);
> 
> In fact, btrfs_print_tree() could replace all the following code.
> Which should further shrink the code size.
> 
Oh..just saw it, the code is copied and pasted from it though.

Thanks,
Su
> Thanks,
> Qu
> 
>> +		if (btrfs_is_leaf(eb)) {
>> +			btrfs_print_leaf(eb);
>> +			goto out;
>> +		}
>> +
>> +		/* We are crossing eb boundary, this node must be corrupted */
>> +		if (nr > BTRFS_NODEPTRS_PER_EXTENT_BUFFER(eb))
>> +			warning(
>> +		"node nr_items corrupted, has %u limit %u, continue anyway",
>> +				nr, BTRFS_NODEPTRS_PER_EXTENT_BUFFER(eb));
>> +		printf(
>> +		"node %llu level %d items %d free %u generation %llu owner ",
>> +		       (unsigned long long)eb->start,
>> +		       btrfs_header_level(eb), nr,
>> +		       (u32)BTRFS_NODEPTRS_PER_EXTENT_BUFFER(eb) - nr,
>> +		       (unsigned long long)btrfs_header_generation(eb));
>> +		print_objectid(stdout, btrfs_header_owner(eb), 0);
>> +		printf("\n");
>> +		print_uuids(eb);
>> +		fflush(stdout);
>> +		ptr_num = BTRFS_NODEPTRS_PER_EXTENT_BUFFER(eb);
>> +		for (i = 0; i < nr && i < ptr_num; i++) {
>> +			u64 blocknr = btrfs_node_blockptr(eb, i);
>> +
>> +			btrfs_node_key(eb, &disk_key, i);
>> +			btrfs_disk_key_to_cpu(&key, &disk_key);
>> +			printf("\t");
>> +			btrfs_print_key(&disk_key);
>> +			printf(" block %llu (%llu) gen %llu\n",
>> +			       (unsigned long long)blocknr,
>> +			       (unsigned long long)blocknr / eb->len,
>> +			       (unsigned long long)btrfs_node_ptr_generation(eb, i));
>> +			fflush(stdout);
>> +		}
>> +
>> +		if (btrfs_header_level(next) != btrfs_header_level(eb) - 1) {
>> +			warning(
>> +				"eb corrupted: parent bytenr %llu slot %d level %d child bytenr %llu level has %d expect %d, skipping the slot",
>> +				btrfs_header_bytenr(eb), i,
>> +				btrfs_header_level(eb),
>> +				btrfs_header_bytenr(next),
>> +				btrfs_header_level(next),
>> +				btrfs_header_level(eb) - 1);
>> +			continue;
>> +		}
>> +	}
>> +
>> +out:
>> +	if (root_objectid == BTRFS_TREE_RELOC_OBJECTID)
>> +		btrfs_free_fs_root(root);
>> +	btrfs_release_path(&path);
>> +}
>> diff --git a/print-tree.h b/print-tree.h
>> index 62667d7f6195..94f231875a6c 100644
>> --- a/print-tree.h
>> +++ b/print-tree.h
>> @@ -26,4 +26,6 @@ void print_chunk_item(struct extent_buffer *eb, struct btrfs_chunk *chunk);
>>   void print_extent_item(struct extent_buffer *eb, int slot, int metadata);
>>   void print_objectid(FILE *stream, u64 objectid, u8 type);
>>   void print_key_type(FILE *stream, u64 objectid, u8 type);
>> +void btrfs_print_spec_key(struct btrfs_fs_info *info, u64 root_objectid,
>> +			  struct btrfs_key *key);
>>   #endif
>>
> 
> 

Re: [PATCH] btrfs-progs: inspect-internal: add option '-k u64,u8,u64' of dump-tree

[Qu Wenruo]

On 2018年07月16日 16:14, Su Yue wrote:
> 
> 
> On 07/16/2018 03:45 PM, Qu Wenruo wrote:
>>
>>
>> On 2018年07月16日 13:55, Su Yue wrote:
>>> For big filesystems, there are many items in trees(extent tree
>>> specially).
>>> For example, to dump one extent, we usually dump extent tree then pipe
>>> result to grep. The time-consuming part is that dump tree traverses
>>> items. And it eats cpu and memory too.
>>>
>>> This patch introduces an option '-k u64,u8,u64' for users(developer more
>>> likely) to appoint a specific key to search and dump, then the path
>>> from root node down the leaf will be dumped.
>>> The search of the key costs most time of this way.
>>
>> Indeed a pretty useful debug oriented feature.
>>
>>>
>>> Signed-off-by: Su Yue <suy.fnst@cn.fujitsu.com>
>>> ---
>>> In my experiment, not usual case though.
>>> Image was provided by Chris Murphy, thanks.
>>>
>>> #btrfs filesystem df /mnt
>>> Data, single: total=767.00GiB, used=766.58GiB
>>> System, DUP: total=32.00MiB, used=112.00KiB
>>> Metadata, DUP: total=5.50GiB, used=4.69GiB
>>> Metadata, single: total=16.00MiB, used=0.00B
>>> GlobalReserve, single: total=512.00MiB, used=0.00B
>>>
>>> Before:
>>> #time bash -c 'btrfs inspect-internal dump-tree -t 2 ~/test/test.img
>>> | grep "1295194308608" >> /dev/null'
>>> real    0m34.024s
>>> user    0m3.269s
>>> sys     0m4.047s
>>>
>>> Patched and use -k:
>>> #time bash -c './btrfs inspect-internal dump-tree -t 2  -k
>>> 1295194308608,0,0 ~/test/test.img >> /dev/null'
>>>
>>> real    0m1.408s
>>> user    0m0.006s
>>> sys     0m0.014s
>>>
>>> The new way is 34 times faster than 'grep' way, uses less memory and
>>> cpu, and it prints path useful for debug.
>>>
>>> ---
>>>   cmds-inspect-dump-tree.c |  54 +++++++++++++++++--
>>>   print-tree.c             | 112 +++++++++++++++++++++++++++++++++++++++
>>>   print-tree.h             |   2 +
>>>   3 files changed, 163 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/cmds-inspect-dump-tree.c b/cmds-inspect-dump-tree.c
>>> index c8acd55a0c3a..2a1a40c8270d 100644
>>> --- a/cmds-inspect-dump-tree.c
>>> +++ b/cmds-inspect-dump-tree.c
>>> @@ -184,6 +184,21 @@ static u64 treeid_from_string(const char *str,
>>> const char **end)
>>>       return id;
>>>   }
>>>   +static int parse_key(struct btrfs_key *key)
>>> +{
>>> +
>>> +    int ret = sscanf(optarg, "%llu,%hhu,%llu", &key->objectid,
>>> +             &key->type, &key->offset);
>>> +    if (ret != 3) {
>>> +        error("error parsing key '%s'\n", optarg);
>>> +        ret = -EINVAL;
>>> +    } else {
>>> +        ret = 0;
>>> +    }
>>> +
>>> +    return ret;
>>> +}
>>> +
>>>   const char * const cmd_inspect_dump_tree_usage[] = {
>>>       "btrfs inspect-internal dump-tree [options] device",
>>>       "Dump tree structures from a given device",
>>> @@ -199,6 +214,7 @@ const char * const cmd_inspect_dump_tree_usage[] = {
>>>       "-u|--uuid              print only the uuid tree",
>>>       "-b|--block <block_num> print info from the specified block only",
>>>       "-t|--tree <tree_id>    print only tree with the given id
>>> (string or number)",
>>> +    "-k|--key <u64,u8,u64>  search the specific key then print path,
>>> must with -t",
>>
>> Shouldn't it conflict with -b and -r?
>>
>>>       "--follow               use with -b, to show all children tree
>>> blocks of <block_num>",
>>>       NULL
>>>   };
>>> @@ -224,8 +240,10 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>>>       unsigned open_ctree_flags;
>>>       u64 block_only = 0;
>>>       struct btrfs_root *tree_root_scan;
>>> +    struct btrfs_key spec_key = { 0 };
>>>       u64 tree_id = 0;
>>>       bool follow = false;
>>> +    bool is_key_spec = false;
>>
>> What about @key_set? @is_key_spec looks a little strange here.
>>
> Ok, will call it is_spec_key_set in next version.
> 
>>>         /*
>>>        * For debug-tree, we care nothing about extent tree (it's just
>>> backref
>>> @@ -248,10 +266,11 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>>>               { "block", required_argument, NULL, 'b'},
>>>               { "tree", required_argument, NULL, 't'},
>>>               { "follow", no_argument, NULL, GETOPT_VAL_FOLLOW },
>>> +            {"key", required_argument, NULL, 'k'},
>>
>> Small alignment mismatch, missing a space before "key".
>>
>>>               { NULL, 0, NULL, 0 }
>>>           };
>>>   -        c = getopt_long(argc, argv, "deb:rRut:", long_options, NULL);
>>> +        c = getopt_long(argc, argv, "deb:rRut:k:", long_options, NULL);
>>>           if (c < 0)
>>>               break;
>>>           switch (c) {
>>> @@ -300,6 +319,12 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>>>               }
>>>               break;
>>>               }
>>> +        case 'k':
>>> +            ret = parse_key(&spec_key);
>>> +            if (ret)
>>> +                exit(1);
>>> +            is_key_spec = true;
>>> +            break;
>>>           case GETOPT_VAL_FOLLOW:
>>>               follow = true;
>>>               break;
>>> @@ -308,6 +333,9 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>>>           }
>>>       }
>>>   +    if (!tree_id && is_key_spec)
>>> +        usage(cmd_inspect_dump_tree_usage);
>>> +
>>>       if (check_argc_exact(argc - optind, 1))
>>>           usage(cmd_inspect_dump_tree_usage);
>>>   @@ -398,7 +426,11 @@ again:
>>>               goto close_root;
>>>           }
>>>           printf("root tree\n");
>>> -        btrfs_print_tree(info->tree_root->node, 1);
>>> +        if (is_key_spec)
>>> +            btrfs_print_spec_key(info, BTRFS_ROOT_TREE_OBJECTID,
>>> +                         &spec_key);
>>> +        else
>>> +            btrfs_print_tree(info->tree_root->node, 1);
>>>           goto close_root;
>>>       }
>>>   @@ -408,7 +440,11 @@ again:
>>>               goto close_root;
>>>           }
>>>           printf("chunk tree\n");
>>> -        btrfs_print_tree(info->chunk_root->node, 1);
>>> +        if (is_key_spec)
>>> +            btrfs_print_spec_key(info, BTRFS_CHUNK_TREE_OBJECTID,
>>> +                         &spec_key);
>>> +        else
>>> +            btrfs_print_tree(info->chunk_root->node, 1);
>>>           goto close_root;
>>>       }
>>>   
>>
>> I really don't thing we need to put btrfS_print_spec_key() here.
>>
>> It's in fact a special case, no need to nest it into the loop.
>> Not to mention it appears 3 times in the main loop.
>>
> Not understood what you mean.

I mean, just put the function call of btrfs_print_spec_key() just after
open_ctree_fs_info().
So it should looks like:

info = open_ctree_fs_info();
if (!info){
	/* error handling */
}
if (is_spec_key_set) {
	ret = btrfs_print_spec_key(info, tree_id, &spec_key);
	if (ret < 0) {
		/* Error handling */
	}
	goto close_root;
}

...

Thanks,
Qu

> 
>>> @@ -418,7 +454,11 @@ again:
>>>               goto close_root;
>>>           }
>>>           printf("log root tree\n");
>>> -        btrfs_print_tree(info->log_root_tree->node, 1);
>>> +        if (is_key_spec)
>>> +            btrfs_print_spec_key(info, BTRFS_TREE_LOG_OBJECTID,
>>> +                         &spec_key);
>>> +        else
>>> +            btrfs_print_tree(info->log_root_tree->node, 1);
>>>           goto close_root;
>>>       }
>>>   @@ -564,7 +604,11 @@ again:
>>>                              btrfs_header_level(buf));
>>>                   } else {
>>>                       printf(" \n");
>>> -                    btrfs_print_tree(buf, 1);
>>> +                    if (is_key_spec)
>>> +                        btrfs_print_spec_key(info,
>>> +                             found_key.objectid, &spec_key);
>>> +                    else
>>> +                        btrfs_print_tree(buf, 1);
>>>                   }
>>>               }
>>>               free_extent_buffer(buf);
>>> diff --git a/print-tree.c b/print-tree.c
>>> index a09ecfbb28f0..f3a19fed8591 100644
>>> --- a/print-tree.c
>>> +++ b/print-tree.c
>>> @@ -1459,3 +1459,115 @@ void btrfs_print_tree(struct extent_buffer
>>> *eb, int follow)
>>>         return;
>>>   }
>>> +
>>> +void btrfs_print_spec_key(struct btrfs_fs_info *fs_info, u64
>>> root_objectid,
>>> +              struct btrfs_key *skey)
>>> +{
>>> +    int i;
>>> +    u32 nr;
>>> +    u32 ptr_num;
>>> +    int ret;
>>> +    int level;
>>> +    struct btrfs_root *root;
>>> +    struct btrfs_disk_key disk_key;
>>> +    struct btrfs_key key;
>>> +    struct extent_buffer *next;
>>> +    struct extent_buffer *eb;
>>> +    struct btrfs_path path;
>>> +
>>> +    key.objectid = root_objectid;
>>> +    key.type = BTRFS_ROOT_ITEM_KEY;
>>> +    key.offset = (u64)-1;
>>> +
>>> +    if (key.objectid == BTRFS_TREE_RELOC_OBJECTID)
>>> +        root = btrfs_read_fs_root_no_cache(fs_info, &key);
>>> +    else
>>> +        root = btrfs_read_fs_root(fs_info, &key);
>>> +
>>> +    if (IS_ERR(root) || !root) {
>>> +        error("failed to read tree: %lld", key.objectid);
>>> +        return;
>>> +    }
>>> +
>>> +    btrfs_init_path(&path);
>>> +    ret = btrfs_search_slot(NULL, root, skey, &path, 0, 0);
>>> +    if (ret < 0) {
>>> +        error("error search the key [%llu, %u, %llu] in root %llu",
>>> +              skey->objectid, skey->type, skey->offset,
>>> root->objectid);
>>> +        goto out;
>>> +    }
>>> +
>>> +    if (ret > 0) {
>>> +        if (path.slots[0] > btrfs_header_nritems(path.nodes[0])) {
>>> +            ret = btrfs_next_item(root, &path);
>>> +            if (ret) {
>>> +                error(
>>> +    "error search the key [%llu, %u, %llu] in root %llu, no next key",
>>> +                    skey->objectid, skey->type,
>>> +                    skey->offset, root->objectid);
>>> +                goto out;
>>> +            }
>>> +        }
>>> +
>>> +        btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
>>> +        printf("next to search key is [%llu, %u, %llu]\n",
>>> +               key.objectid, key.type, key.offset);
>>> +    }
>>> +
>>> +    level = btrfs_header_level(root->node);
>>> +    for (; level >= 0 ; --level) {
>>> +        eb = path.nodes[level];
>>> +        next = path.nodes[level - 1];
>>> +        nr = btrfs_header_nritems(eb);
>>
>> In fact, btrfs_print_tree() could replace all the following code.
>> Which should further shrink the code size.
>>
> Oh..just saw it, the code is copied and pasted from it though.
> 
> Thanks,
> Su
>> Thanks,
>> Qu
>>
>>> +        if (btrfs_is_leaf(eb)) {
>>> +            btrfs_print_leaf(eb);
>>> +            goto out;
>>> +        }
>>> +
>>> +        /* We are crossing eb boundary, this node must be corrupted */
>>> +        if (nr > BTRFS_NODEPTRS_PER_EXTENT_BUFFER(eb))
>>> +            warning(
>>> +        "node nr_items corrupted, has %u limit %u, continue anyway",
>>> +                nr, BTRFS_NODEPTRS_PER_EXTENT_BUFFER(eb));
>>> +        printf(
>>> +        "node %llu level %d items %d free %u generation %llu owner ",
>>> +               (unsigned long long)eb->start,
>>> +               btrfs_header_level(eb), nr,
>>> +               (u32)BTRFS_NODEPTRS_PER_EXTENT_BUFFER(eb) - nr,
>>> +               (unsigned long long)btrfs_header_generation(eb));
>>> +        print_objectid(stdout, btrfs_header_owner(eb), 0);
>>> +        printf("\n");
>>> +        print_uuids(eb);
>>> +        fflush(stdout);
>>> +        ptr_num = BTRFS_NODEPTRS_PER_EXTENT_BUFFER(eb);
>>> +        for (i = 0; i < nr && i < ptr_num; i++) {
>>> +            u64 blocknr = btrfs_node_blockptr(eb, i);
>>> +
>>> +            btrfs_node_key(eb, &disk_key, i);
>>> +            btrfs_disk_key_to_cpu(&key, &disk_key);
>>> +            printf("\t");
>>> +            btrfs_print_key(&disk_key);
>>> +            printf(" block %llu (%llu) gen %llu\n",
>>> +                   (unsigned long long)blocknr,
>>> +                   (unsigned long long)blocknr / eb->len,
>>> +                   (unsigned long long)btrfs_node_ptr_generation(eb,
>>> i));
>>> +            fflush(stdout);
>>> +        }
>>> +
>>> +        if (btrfs_header_level(next) != btrfs_header_level(eb) - 1) {
>>> +            warning(
>>> +                "eb corrupted: parent bytenr %llu slot %d level %d
>>> child bytenr %llu level has %d expect %d, skipping the slot",
>>> +                btrfs_header_bytenr(eb), i,
>>> +                btrfs_header_level(eb),
>>> +                btrfs_header_bytenr(next),
>>> +                btrfs_header_level(next),
>>> +                btrfs_header_level(eb) - 1);
>>> +            continue;
>>> +        }
>>> +    }
>>> +
>>> +out:
>>> +    if (root_objectid == BTRFS_TREE_RELOC_OBJECTID)
>>> +        btrfs_free_fs_root(root);
>>> +    btrfs_release_path(&path);
>>> +}
>>> diff --git a/print-tree.h b/print-tree.h
>>> index 62667d7f6195..94f231875a6c 100644
>>> --- a/print-tree.h
>>> +++ b/print-tree.h
>>> @@ -26,4 +26,6 @@ void print_chunk_item(struct extent_buffer *eb,
>>> struct btrfs_chunk *chunk);
>>>   void print_extent_item(struct extent_buffer *eb, int slot, int
>>> metadata);
>>>   void print_objectid(FILE *stream, u64 objectid, u8 type);
>>>   void print_key_type(FILE *stream, u64 objectid, u8 type);
>>> +void btrfs_print_spec_key(struct btrfs_fs_info *info, u64
>>> root_objectid,
>>> +              struct btrfs_key *key);
>>>   #endif
>>>
>>
>>
> 
> 
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