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

[Su Yue <suy.fnst@cn.fujitsu.com>]

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
>>
> 
>