[PATCH v4] btrfs-progs: dump-tree: add noscan option

[PATCH v4] btrfs-progs: dump-tree: add noscan option

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

There is no way to dump tree from a disk in the degraded mode.
Such as, when you specify a device for the cli 'btrfs inspect
dump-tree /dev/sda' it would invariably scan for its partner devices
to built and print the tree. This approach at times defeats the purpose.
Suppose in RAID1 if you want to review each mirror separately as of now
there is no way you can do that. So this patch adds an option --noscan
for example:
  'btrfs inspect dump-tree --noscan <dev> [<dev>..]'
with which it shall not scan for the other devices to report the tree, and
helps debug RAID1s.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
v3->v4: change the patch title.
	collapse scan_args() to its only parent cmd_inspect_dump_tree()
	(it was bit confusing).
	update the change log.
	update usage.
	update man page.
v2->v3: make it scalable for more than two disks in noscan mode
v1->v2: rename --degraded to --noscan
---
 Documentation/btrfs-inspect-internal.asciidoc |  5 ++-
 cmds-inspect-dump-tree.c                      | 57 ++++++++++++++++++++-------
 2 files changed, 47 insertions(+), 15 deletions(-)

diff --git a/Documentation/btrfs-inspect-internal.asciidoc b/Documentation/btrfs-inspect-internal.asciidoc
index 381497d284b8..f9d7f1c58f00 100644
--- a/Documentation/btrfs-inspect-internal.asciidoc
+++ b/Documentation/btrfs-inspect-internal.asciidoc
@@ -61,7 +61,7 @@ specify which mirror to print, valid values are 0, 1 and 2 and the superblock
 must be present on the device with a valid signature, can be used together with
 '--force'
 
-*dump-tree* [options] <device>::
+*dump-tree* [options] <device> [device...]::
 (replaces the standalone tool *btrfs-debug-tree*)
 +
 Dump tree structures from a given device in textual form, expand keys to human
@@ -95,6 +95,9 @@ intermixed in the output
 --bfs::::
 use breadth-first search to print trees. the nodes are printed before all
 leaves
+--noscan::::
+do not scan the system for other partner device(s), only use the device(s)
+provided in the argument
 -t <tree_id>::::
 print only the tree with the specified ID, where the ID can be numerical or
 common name in a flexible human readable form
diff --git a/cmds-inspect-dump-tree.c b/cmds-inspect-dump-tree.c
index ad5345b4f1db..9dd040e5de17 100644
--- a/cmds-inspect-dump-tree.c
+++ b/cmds-inspect-dump-tree.c
@@ -21,6 +21,7 @@
 #include <unistd.h>
 #include <uuid/uuid.h>
 #include <getopt.h>
+#include <fcntl.h>
 
 #include "kerncompat.h"
 #include "radix-tree.h"
@@ -185,7 +186,7 @@ static u64 treeid_from_string(const char *str, const char **end)
 }
 
 const char * const cmd_inspect_dump_tree_usage[] = {
-	"btrfs inspect-internal dump-tree [options] device",
+	"btrfs inspect-internal dump-tree [options] <device> [<device> ..]",
 	"Dump tree structures from a given device",
 	"Dump tree structures from a given device in textual form, expand keys to human",
 	"readable equivalents where possible.",
@@ -200,6 +201,7 @@ const char * const cmd_inspect_dump_tree_usage[] = {
 	"-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)",
 	"--follow               use with -b, to show all children tree blocks of <block_num>",
+	"--noscan               do not scan for the partner device(s)",
 	NULL
 };
 
@@ -214,7 +216,7 @@ int cmd_inspect_dump_tree(int argc, char **argv)
 	struct btrfs_disk_key disk_key;
 	struct btrfs_key found_key;
 	char uuidbuf[BTRFS_UUID_UNPARSED_SIZE];
-	int ret;
+	int ret = 0;
 	int slot;
 	int extent_only = 0;
 	int device_only = 0;
@@ -222,6 +224,7 @@ int cmd_inspect_dump_tree(int argc, char **argv)
 	int roots_only = 0;
 	int root_backups = 0;
 	int traverse = BTRFS_PRINT_TREE_DEFAULT;
+	int dev_optind;
 	unsigned open_ctree_flags;
 	u64 block_only = 0;
 	struct btrfs_root *tree_root_scan;
@@ -239,8 +242,8 @@ int cmd_inspect_dump_tree(int argc, char **argv)
 	optind = 0;
 	while (1) {
 		int c;
-		enum { GETOPT_VAL_FOLLOW = 256, GETOPT_VAL_DFS,
-		       GETOPT_VAL_BFS };
+		enum { GETOPT_VAL_FOLLOW = 256, GETOPT_VAL_DFS, GETOPT_VAL_BFS,
+		       GETOPT_VAL_NOSCAN};
 		static const struct option long_options[] = {
 			{ "extents", no_argument, NULL, 'e'},
 			{ "device", no_argument, NULL, 'd'},
@@ -252,6 +255,7 @@ int cmd_inspect_dump_tree(int argc, char **argv)
 			{ "follow", no_argument, NULL, GETOPT_VAL_FOLLOW },
 			{ "bfs", no_argument, NULL, GETOPT_VAL_BFS },
 			{ "dfs", no_argument, NULL, GETOPT_VAL_DFS },
+			{ "noscan", no_argument, NULL, GETOPT_VAL_NOSCAN },
 			{ NULL, 0, NULL, 0 }
 		};
 
@@ -313,24 +317,49 @@ int cmd_inspect_dump_tree(int argc, char **argv)
 		case GETOPT_VAL_BFS:
 			traverse = BTRFS_PRINT_TREE_BFS;
 			break;
+		case GETOPT_VAL_NOSCAN:
+			open_ctree_flags |= OPEN_CTREE_NO_DEVICES;
+			break;
 		default:
 			usage(cmd_inspect_dump_tree_usage);
 		}
 	}
 
-	if (check_argc_exact(argc - optind, 1))
+	if (check_argc_min(argc - optind, 1))
 		usage(cmd_inspect_dump_tree_usage);
 
-	ret = check_arg_type(argv[optind]);
-	if (ret != BTRFS_ARG_BLKDEV && ret != BTRFS_ARG_REG) {
-		if (ret < 0) {
-			errno = -ret;
-			error("invalid argument %s: %m", argv[optind]);
-		} else {
-			error("not a block device or regular file: %s",
-			      argv[optind]);
+	dev_optind = optind;
+	while (dev_optind < argc) {
+		int fd;
+		struct btrfs_fs_devices *fs_devices;
+		u64 num_devices;
+
+		ret = check_arg_type(argv[optind]);
+		if (ret != BTRFS_ARG_BLKDEV && ret != BTRFS_ARG_REG) {
+			if (ret < 0) {
+				errno = -ret;
+				error("invalid argument %s: %m", argv[dev_optind]);
+			} else {
+				error("not a block device or regular file: %s",
+				       argv[dev_optind]);
+			}
 		}
-		goto out;
+		fd = open(argv[dev_optind], O_RDONLY);
+		if (fd < 0) {
+			error("cannot open %s: %m", argv[dev_optind]);
+			return -EINVAL;
+		}
+		ret = btrfs_scan_one_device(fd, argv[dev_optind], &fs_devices,
+					    &num_devices,
+					    BTRFS_SUPER_INFO_OFFSET,
+					    SBREAD_DEFAULT);
+		close(fd);
+		if (ret) {
+			error("device scan %s: %s", argv[dev_optind],
+			       strerror(-ret));
+			return ret;
+		}
+		dev_optind++;
 	}
 
 	printf("%s\n", PACKAGE_STRING);
-- 
1.8.3.1

Re: [PATCH v4] btrfs-progs: dump-tree: add noscan option

[Nikolay Borisov]

On 28.02.19 г. 8:54 ч., Anand Jain wrote:
> From: Anand Jain <Anand.Jain@oracle.com>
> 
> There is no way to dump tree from a disk in the degraded mode.
> Such as, when you specify a device for the cli 'btrfs inspect
> dump-tree /dev/sda' it would invariably scan for its partner devices
> to built and print the tree. This approach at times defeats the purpose.

define "at times" which are those times?

> Suppose in RAID1 if you want to review each mirror separately as of now
> there is no way you can do that. So this patch adds an option --noscan
> for example:
>   'btrfs inspect dump-tree --noscan <dev> [<dev>..]'
> with which it shall not scan for the other devices to report the tree, and
> helps debug RAID1s.

This example contradicts what the code is doing, with this patch you
will call btrfs_scan_one_device for every device passed to the noscan
option?

> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> v3->v4: change the patch title.
> 	collapse scan_args() to its only parent cmd_inspect_dump_tree()
> 	(it was bit confusing).
> 	update the change log.
> 	update usage.
> 	update man page.
> v2->v3: make it scalable for more than two disks in noscan mode
> v1->v2: rename --degraded to --noscan

So what problem is this actually trying to solve? The following succeeds
for me with btrfs-progs 4.17.1:

root@ubuntu-virtual:~# losetup -f file1.img
root@ubuntu-virtual:~# losetup -f file2.img
root@ubuntu-virtual:~# mkfs.btrfs -m raid1 /dev/loop1 /dev/loop0
losetup -d /dev/loop1
root@ubuntu-virtual:~# mount /dev/loop0 /media/scratch/
mount: wrong fs type, bad option, bad superblock on /dev/loop0,
       missing codepage or helper program, or other error

       In some cases useful info is found in syslog - try
       dmesg | tail or so.


root@ubuntu-virtual:~# btrfs inspect-internal dump-tree /dev/loop0
btrfs-progs v4.17.1
warning, device 1 is missing
root tree
leaf 30556160 items 10 free space 13173 generation 5 owner ROOT_TREE
leaf 30556160 flags 0x1(WRITTEN) backref revision 1
fs uuid 8727408c-b1af-4c14-b63b-51b12bcff933
chunk uuid 5ebde928-324f-42d0-98c6-f953d680fc21
	item 0 key (EXTENT_TREE ROOT_ITEM 0) itemoff 15844 itemsize 439
		generation 5 root_dirid 0 bytenr 30523392 level 0 refs 1
.................



Your changelog definitely needs rewriting to make it clear what you are
trying to do.

> ---
>  Documentation/btrfs-inspect-internal.asciidoc |  5 ++-
>  cmds-inspect-dump-tree.c                      | 57 ++++++++++++++++++++-------
>  2 files changed, 47 insertions(+), 15 deletions(-)
> 
> diff --git a/Documentation/btrfs-inspect-internal.asciidoc b/Documentation/btrfs-inspect-internal.asciidoc
> index 381497d284b8..f9d7f1c58f00 100644
> --- a/Documentation/btrfs-inspect-internal.asciidoc
> +++ b/Documentation/btrfs-inspect-internal.asciidoc
> @@ -61,7 +61,7 @@ specify which mirror to print, valid values are 0, 1 and 2 and the superblock
>  must be present on the device with a valid signature, can be used together with
>  '--force'
>  
> -*dump-tree* [options] <device>::
> +*dump-tree* [options] <device> [device...]::
>  (replaces the standalone tool *btrfs-debug-tree*)
>  +
>  Dump tree structures from a given device in textual form, expand keys to human
> @@ -95,6 +95,9 @@ intermixed in the output
>  --bfs::::
>  use breadth-first search to print trees. the nodes are printed before all
>  leaves
> +--noscan::::
> +do not scan the system for other partner device(s), only use the device(s)
> +provided in the argument
>  -t <tree_id>::::
>  print only the tree with the specified ID, where the ID can be numerical or
>  common name in a flexible human readable form
> diff --git a/cmds-inspect-dump-tree.c b/cmds-inspect-dump-tree.c
> index ad5345b4f1db..9dd040e5de17 100644
> --- a/cmds-inspect-dump-tree.c
> +++ b/cmds-inspect-dump-tree.c
> @@ -21,6 +21,7 @@
>  #include <unistd.h>
>  #include <uuid/uuid.h>
>  #include <getopt.h>
> +#include <fcntl.h>
>  
>  #include "kerncompat.h"
>  #include "radix-tree.h"
> @@ -185,7 +186,7 @@ static u64 treeid_from_string(const char *str, const char **end)
>  }
>  
>  const char * const cmd_inspect_dump_tree_usage[] = {
> -	"btrfs inspect-internal dump-tree [options] device",
> +	"btrfs inspect-internal dump-tree [options] <device> [<device> ..]",
>  	"Dump tree structures from a given device",
>  	"Dump tree structures from a given device in textual form, expand keys to human",
>  	"readable equivalents where possible.",
> @@ -200,6 +201,7 @@ const char * const cmd_inspect_dump_tree_usage[] = {
>  	"-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)",
>  	"--follow               use with -b, to show all children tree blocks of <block_num>",
> +	"--noscan               do not scan for the partner device(s)",
>  	NULL
>  };
>  
> @@ -214,7 +216,7 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>  	struct btrfs_disk_key disk_key;
>  	struct btrfs_key found_key;
>  	char uuidbuf[BTRFS_UUID_UNPARSED_SIZE];
> -	int ret;
> +	int ret = 0;
>  	int slot;
>  	int extent_only = 0;
>  	int device_only = 0;
> @@ -222,6 +224,7 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>  	int roots_only = 0;
>  	int root_backups = 0;
>  	int traverse = BTRFS_PRINT_TREE_DEFAULT;
> +	int dev_optind;
>  	unsigned open_ctree_flags;
>  	u64 block_only = 0;
>  	struct btrfs_root *tree_root_scan;
> @@ -239,8 +242,8 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>  	optind = 0;
>  	while (1) {
>  		int c;
> -		enum { GETOPT_VAL_FOLLOW = 256, GETOPT_VAL_DFS,
> -		       GETOPT_VAL_BFS };
> +		enum { GETOPT_VAL_FOLLOW = 256, GETOPT_VAL_DFS, GETOPT_VAL_BFS,
> +		       GETOPT_VAL_NOSCAN};
>  		static const struct option long_options[] = {
>  			{ "extents", no_argument, NULL, 'e'},
>  			{ "device", no_argument, NULL, 'd'},
> @@ -252,6 +255,7 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>  			{ "follow", no_argument, NULL, GETOPT_VAL_FOLLOW },
>  			{ "bfs", no_argument, NULL, GETOPT_VAL_BFS },
>  			{ "dfs", no_argument, NULL, GETOPT_VAL_DFS },
> +			{ "noscan", no_argument, NULL, GETOPT_VAL_NOSCAN },
>  			{ NULL, 0, NULL, 0 }
>  		};
>  
> @@ -313,24 +317,49 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>  		case GETOPT_VAL_BFS:
>  			traverse = BTRFS_PRINT_TREE_BFS;
>  			break;
> +		case GETOPT_VAL_NOSCAN:
> +			open_ctree_flags |= OPEN_CTREE_NO_DEVICES;
> +			break;
>  		default:
>  			usage(cmd_inspect_dump_tree_usage);
>  		}
>  	}
>  
> -	if (check_argc_exact(argc - optind, 1))
> +	if (check_argc_min(argc - optind, 1))
>  		usage(cmd_inspect_dump_tree_usage);
>  
> -	ret = check_arg_type(argv[optind]);
> -	if (ret != BTRFS_ARG_BLKDEV && ret != BTRFS_ARG_REG) {
> -		if (ret < 0) {
> -			errno = -ret;
> -			error("invalid argument %s: %m", argv[optind]);
> -		} else {
> -			error("not a block device or regular file: %s",
> -			      argv[optind]);
> +	dev_optind = optind;
> +	while (dev_optind < argc) {
> +		int fd;
> +		struct btrfs_fs_devices *fs_devices;
> +		u64 num_devices;
> +
> +		ret = check_arg_type(argv[optind]);
> +		if (ret != BTRFS_ARG_BLKDEV && ret != BTRFS_ARG_REG) {
> +			if (ret < 0) {
> +				errno = -ret;
> +				error("invalid argument %s: %m", argv[dev_optind]);
> +			} else {
> +				error("not a block device or regular file: %s",
> +				       argv[dev_optind]);
> +			}
>  		}
> -		goto out;
> +		fd = open(argv[dev_optind], O_RDONLY);
> +		if (fd < 0) {
> +			error("cannot open %s: %m", argv[dev_optind]);
> +			return -EINVAL;
> +		}
> +		ret = btrfs_scan_one_device(fd, argv[dev_optind], &fs_devices,
> +					    &num_devices,
> +					    BTRFS_SUPER_INFO_OFFSET,
> +					    SBREAD_DEFAULT);
> +		close(fd);
> +		if (ret) {
> +			error("device scan %s: %s", argv[dev_optind],
> +			       strerror(-ret));
> +			return ret;
> +		}
> +		dev_optind++;
>  	}
>  
>  	printf("%s\n", PACKAGE_STRING);
> 

Re: [PATCH v4] btrfs-progs: dump-tree: add noscan option

[Anand Jain]

On 3/11/19 6:11 PM, Nikolay Borisov wrote:
> 
> 
> On 28.02.19 г. 8:54 ч., Anand Jain wrote:
>> From: Anand Jain <Anand.Jain@oracle.com>
>>
>> There is no way to dump tree from a disk in the degraded mode.
>> Such as, when you specify a device for the cli 'btrfs inspect
>> dump-tree /dev/sda' it would invariably scan for its partner devices
>> to built and print the tree. This approach at times defeats the purpose.
> 
> define "at times" which are those times?

  Its already defined as below. Will reword or state it explicitly.

>> Suppose in RAID1 if you want to review each mirror separately as of now
>> there is no way you can do that. So this patch adds an option --noscan
>> for example:
>>    'btrfs inspect dump-tree --noscan <dev> [<dev>..]'
>> with which it shall not scan for the other devices to report the tree, and
>> helps debug RAID1s.
> 
> This example contradicts what the code is doing,

  No. did you miss the flag OPEN_CTREE_NO_DEVICES at [1] below. ?
  Which means it does not scan the system for the btrfs devices.

> with this patch you
> will call btrfs_scan_one_device for every device passed to the noscan
> option?

  That's right. Its correct behavior.

>>
>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
>> v3->v4: change the patch title.
>> 	collapse scan_args() to its only parent cmd_inspect_dump_tree()
>> 	(it was bit confusing).
>> 	update the change log.
>> 	update usage.
>> 	update man page.
>> v2->v3: make it scalable for more than two disks in noscan mode
>> v1->v2: rename --degraded to --noscan
> 
> So what problem is this actually trying to solve? The following succeeds
> for me with btrfs-progs 4.17.1:

> root@ubuntu-virtual:~# losetup -f file1.img
> root@ubuntu-virtual:~# losetup -f file2.img
> root@ubuntu-virtual:~# mkfs.btrfs -m raid1 /dev/loop1 /dev/loop0
> losetup -d /dev/loop1
> root@ubuntu-virtual:~# mount /dev/loop0 /media/scratch/
> mount: wrong fs type, bad option, bad superblock on /dev/loop0,
>         missing codepage or helper program, or other error
> 
>         In some cases useful info is found in syslog - try
>         dmesg | tail or so.
> 
> 
> root@ubuntu-virtual:~# btrfs inspect-internal dump-tree /dev/loop0
> btrfs-progs v4.17.1
> warning, device 1 is missing
> root tree
> leaf 30556160 items 10 free space 13173 generation 5 owner ROOT_TREE
> leaf 30556160 flags 0x1(WRITTEN) backref revision 1
> fs uuid 8727408c-b1af-4c14-b63b-51b12bcff933
> chunk uuid 5ebde928-324f-42d0-98c6-f953d680fc21
> 	item 0 key (EXTENT_TREE ROOT_ITEM 0) itemoff 15844 itemsize 439
> 		generation 5 root_dirid 0 bytenr 30523392 level 0 refs 1
> .................
> 
> 
> 
> Your changelog definitely needs rewriting to make it clear what you are
> trying to do.

  In your example above /dev/loop1 is destroyed. So are you suggesting to
  destroy the partner device to dump-tree in degraded mode? That's not
  a viable workaround.

Thanks, Anand

>> ---
>>   Documentation/btrfs-inspect-internal.asciidoc |  5 ++-
>>   cmds-inspect-dump-tree.c                      | 57 ++++++++++++++++++++-------
>>   2 files changed, 47 insertions(+), 15 deletions(-)
>>
>> diff --git a/Documentation/btrfs-inspect-internal.asciidoc b/Documentation/btrfs-inspect-internal.asciidoc
>> index 381497d284b8..f9d7f1c58f00 100644
>> --- a/Documentation/btrfs-inspect-internal.asciidoc
>> +++ b/Documentation/btrfs-inspect-internal.asciidoc
>> @@ -61,7 +61,7 @@ specify which mirror to print, valid values are 0, 1 and 2 and the superblock
>>   must be present on the device with a valid signature, can be used together with
>>   '--force'
>>   
>> -*dump-tree* [options] <device>::
>> +*dump-tree* [options] <device> [device...]::
>>   (replaces the standalone tool *btrfs-debug-tree*)
>>   +
>>   Dump tree structures from a given device in textual form, expand keys to human
>> @@ -95,6 +95,9 @@ intermixed in the output
>>   --bfs::::
>>   use breadth-first search to print trees. the nodes are printed before all
>>   leaves
>> +--noscan::::
>> +do not scan the system for other partner device(s), only use the device(s)
>> +provided in the argument
>>   -t <tree_id>::::
>>   print only the tree with the specified ID, where the ID can be numerical or
>>   common name in a flexible human readable form
>> diff --git a/cmds-inspect-dump-tree.c b/cmds-inspect-dump-tree.c
>> index ad5345b4f1db..9dd040e5de17 100644
>> --- a/cmds-inspect-dump-tree.c
>> +++ b/cmds-inspect-dump-tree.c
>> @@ -21,6 +21,7 @@
>>   #include <unistd.h>
>>   #include <uuid/uuid.h>
>>   #include <getopt.h>
>> +#include <fcntl.h>
>>   
>>   #include "kerncompat.h"
>>   #include "radix-tree.h"
>> @@ -185,7 +186,7 @@ static u64 treeid_from_string(const char *str, const char **end)
>>   }
>>   
>>   const char * const cmd_inspect_dump_tree_usage[] = {
>> -	"btrfs inspect-internal dump-tree [options] device",
>> +	"btrfs inspect-internal dump-tree [options] <device> [<device> ..]",
>>   	"Dump tree structures from a given device",
>>   	"Dump tree structures from a given device in textual form, expand keys to human",
>>   	"readable equivalents where possible.",
>> @@ -200,6 +201,7 @@ const char * const cmd_inspect_dump_tree_usage[] = {
>>   	"-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)",
>>   	"--follow               use with -b, to show all children tree blocks of <block_num>",
>> +	"--noscan               do not scan for the partner device(s)",
>>   	NULL
>>   };
>>   
>> @@ -214,7 +216,7 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>>   	struct btrfs_disk_key disk_key;
>>   	struct btrfs_key found_key;
>>   	char uuidbuf[BTRFS_UUID_UNPARSED_SIZE];
>> -	int ret;
>> +	int ret = 0;
>>   	int slot;
>>   	int extent_only = 0;
>>   	int device_only = 0;
>> @@ -222,6 +224,7 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>>   	int roots_only = 0;
>>   	int root_backups = 0;
>>   	int traverse = BTRFS_PRINT_TREE_DEFAULT;
>> +	int dev_optind;
>>   	unsigned open_ctree_flags;
>>   	u64 block_only = 0;
>>   	struct btrfs_root *tree_root_scan;
>> @@ -239,8 +242,8 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>>   	optind = 0;
>>   	while (1) {
>>   		int c;
>> -		enum { GETOPT_VAL_FOLLOW = 256, GETOPT_VAL_DFS,
>> -		       GETOPT_VAL_BFS };
>> +		enum { GETOPT_VAL_FOLLOW = 256, GETOPT_VAL_DFS, GETOPT_VAL_BFS,
>> +		       GETOPT_VAL_NOSCAN};
>>   		static const struct option long_options[] = {
>>   			{ "extents", no_argument, NULL, 'e'},
>>   			{ "device", no_argument, NULL, 'd'},
>> @@ -252,6 +255,7 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>>   			{ "follow", no_argument, NULL, GETOPT_VAL_FOLLOW },
>>   			{ "bfs", no_argument, NULL, GETOPT_VAL_BFS },
>>   			{ "dfs", no_argument, NULL, GETOPT_VAL_DFS },
>> +			{ "noscan", no_argument, NULL, GETOPT_VAL_NOSCAN },
>>   			{ NULL, 0, NULL, 0 }
>>   		};
>>   
>> @@ -313,24 +317,49 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>>   		case GETOPT_VAL_BFS:
>>   			traverse = BTRFS_PRINT_TREE_BFS;
>>   			break;
>> +		case GETOPT_VAL_NOSCAN:
>> +			open_ctree_flags |= OPEN_CTREE_NO_DEVICES;  <--- [1]
>> +			break;
>>   		default:
>>   			usage(cmd_inspect_dump_tree_usage);
>>   		}
>>   	}
>>   
>> -	if (check_argc_exact(argc - optind, 1))
>> +	if (check_argc_min(argc - optind, 1))
>>   		usage(cmd_inspect_dump_tree_usage);
>>   
>> -	ret = check_arg_type(argv[optind]);
>> -	if (ret != BTRFS_ARG_BLKDEV && ret != BTRFS_ARG_REG) {
>> -		if (ret < 0) {
>> -			errno = -ret;
>> -			error("invalid argument %s: %m", argv[optind]);
>> -		} else {
>> -			error("not a block device or regular file: %s",
>> -			      argv[optind]);
>> +	dev_optind = optind;
>> +	while (dev_optind < argc) {
>> +		int fd;
>> +		struct btrfs_fs_devices *fs_devices;
>> +		u64 num_devices;
>> +
>> +		ret = check_arg_type(argv[optind]);
>> +		if (ret != BTRFS_ARG_BLKDEV && ret != BTRFS_ARG_REG) {
>> +			if (ret < 0) {
>> +				errno = -ret;
>> +				error("invalid argument %s: %m", argv[dev_optind]);
>> +			} else {
>> +				error("not a block device or regular file: %s",
>> +				       argv[dev_optind]);
>> +			}
>>   		}
>> -		goto out;
>> +		fd = open(argv[dev_optind], O_RDONLY);
>> +		if (fd < 0) {
>> +			error("cannot open %s: %m", argv[dev_optind]);
>> +			return -EINVAL;
>> +		}
>> +		ret = btrfs_scan_one_device(fd, argv[dev_optind], &fs_devices,
>> +					    &num_devices,
>> +					    BTRFS_SUPER_INFO_OFFSET,
>> +					    SBREAD_DEFAULT);
>> +		close(fd);
>> +		if (ret) {
>> +			error("device scan %s: %s", argv[dev_optind],
>> +			       strerror(-ret));
>> +			return ret;
>> +		}
>> +		dev_optind++;
>>   	}
>>   
>>   	printf("%s\n", PACKAGE_STRING);
>>

Re: [PATCH v4] btrfs-progs: dump-tree: add noscan option

[Nikolay Borisov]

On 11.03.19 г. 16:44 ч., Anand Jain wrote:
> 
> 
> On 3/11/19 6:11 PM, Nikolay Borisov wrote:
>>
>>
>> On 28.02.19 г. 8:54 ч., Anand Jain wrote:
>>> From: Anand Jain <Anand.Jain@oracle.com>
>>>
>>> There is no way to dump tree from a disk in the degraded mode.
>>> Such as, when you specify a device for the cli 'btrfs inspect
>>> dump-tree /dev/sda' it would invariably scan for its partner devices
>>> to built and print the tree. This approach at times defeats the purpose.
>>
>> define "at times" which are those times?
> 
>  Its already defined as below. Will reword or state it explicitly.
> 
>>> Suppose in RAID1 if you want to review each mirror separately as of now
>>> there is no way you can do that. So this patch adds an option --noscan
>>> for example:
>>>    'btrfs inspect dump-tree --noscan <dev> [<dev>..]'
>>> with which it shall not scan for the other devices to report the
>>> tree, and
>>> helps debug RAID1s.
>>
>> This example contradicts what the code is doing,
> 
>  No. did you miss the flag OPEN_CTREE_NO_DEVICES at [1] below. ?
>  Which means it does not scan the system for the btrfs devices.
> 
>> with this patch you
>> will call btrfs_scan_one_device for every device passed to the noscan
>> option?
> 
>  That's right. Its correct behavior.
> 
>>>
>>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
>>> v3->v4: change the patch title.
>>>     collapse scan_args() to its only parent cmd_inspect_dump_tree()
>>>     (it was bit confusing).
>>>     update the change log.
>>>     update usage.
>>>     update man page.
>>> v2->v3: make it scalable for more than two disks in noscan mode
>>> v1->v2: rename --degraded to --noscan
>>
>> So what problem is this actually trying to solve? The following succeeds
>> for me with btrfs-progs 4.17.1:
> 
>> root@ubuntu-virtual:~# losetup -f file1.img
>> root@ubuntu-virtual:~# losetup -f file2.img
>> root@ubuntu-virtual:~# mkfs.btrfs -m raid1 /dev/loop1 /dev/loop0
>> losetup -d /dev/loop1
>> root@ubuntu-virtual:~# mount /dev/loop0 /media/scratch/
>> mount: wrong fs type, bad option, bad superblock on /dev/loop0,
>>         missing codepage or helper program, or other error
>>
>>         In some cases useful info is found in syslog - try
>>         dmesg | tail or so.
>>
>>
>> root@ubuntu-virtual:~# btrfs inspect-internal dump-tree /dev/loop0
>> btrfs-progs v4.17.1
>> warning, device 1 is missing
>> root tree
>> leaf 30556160 items 10 free space 13173 generation 5 owner ROOT_TREE
>> leaf 30556160 flags 0x1(WRITTEN) backref revision 1
>> fs uuid 8727408c-b1af-4c14-b63b-51b12bcff933
>> chunk uuid 5ebde928-324f-42d0-98c6-f953d680fc21
>>     item 0 key (EXTENT_TREE ROOT_ITEM 0) itemoff 15844 itemsize 439
>>         generation 5 root_dirid 0 bytenr 30523392 level 0 refs 1
>> .................
>>
>>
>>
>> Your changelog definitely needs rewriting to make it clear what you are
>> trying to do.
> 
>  In your example above /dev/loop1 is destroyed. So are you suggesting to
>  destroy the partner device to dump-tree in degraded mode? That's not
>  a viable workaround.

From your changelog I was left with the impression it's not possible to
issue dump-tree for a device whose counterpart is missing. Clearly
that's not what you are fixing so you have to be more eloquent in your
changelogs if you want people to quickly grasp what you are trying to do.

> 
> Thanks, Anand
> 
>>> ---
>>>   Documentation/btrfs-inspect-internal.asciidoc |  5 ++-
>>>   cmds-inspect-dump-tree.c                      | 57
>>> ++++++++++++++++++++-------
>>>   2 files changed, 47 insertions(+), 15 deletions(-)
>>>
>>> diff --git a/Documentation/btrfs-inspect-internal.asciidoc
>>> b/Documentation/btrfs-inspect-internal.asciidoc
>>> index 381497d284b8..f9d7f1c58f00 100644
>>> --- a/Documentation/btrfs-inspect-internal.asciidoc
>>> +++ b/Documentation/btrfs-inspect-internal.asciidoc
>>> @@ -61,7 +61,7 @@ specify which mirror to print, valid values are 0,
>>> 1 and 2 and the superblock
>>>   must be present on the device with a valid signature, can be used
>>> together with
>>>   '--force'
>>>   -*dump-tree* [options] <device>::
>>> +*dump-tree* [options] <device> [device...]::
>>>   (replaces the standalone tool *btrfs-debug-tree*)
>>>   +
>>>   Dump tree structures from a given device in textual form, expand
>>> keys to human
>>> @@ -95,6 +95,9 @@ intermixed in the output
>>>   --bfs::::
>>>   use breadth-first search to print trees. the nodes are printed
>>> before all
>>>   leaves
>>> +--noscan::::
>>> +do not scan the system for other partner device(s), only use the
>>> device(s)
>>> +provided in the argument
>>>   -t <tree_id>::::
>>>   print only the tree with the specified ID, where the ID can be
>>> numerical or
>>>   common name in a flexible human readable form
>>> diff --git a/cmds-inspect-dump-tree.c b/cmds-inspect-dump-tree.c
>>> index ad5345b4f1db..9dd040e5de17 100644
>>> --- a/cmds-inspect-dump-tree.c
>>> +++ b/cmds-inspect-dump-tree.c
>>> @@ -21,6 +21,7 @@
>>>   #include <unistd.h>
>>>   #include <uuid/uuid.h>
>>>   #include <getopt.h>
>>> +#include <fcntl.h>
>>>     #include "kerncompat.h"
>>>   #include "radix-tree.h"
>>> @@ -185,7 +186,7 @@ static u64 treeid_from_string(const char *str,
>>> const char **end)
>>>   }
>>>     const char * const cmd_inspect_dump_tree_usage[] = {
>>> -    "btrfs inspect-internal dump-tree [options] device",
>>> +    "btrfs inspect-internal dump-tree [options] <device> [<device>
>>> ..]",
>>>       "Dump tree structures from a given device",
>>>       "Dump tree structures from a given device in textual form,
>>> expand keys to human",
>>>       "readable equivalents where possible.",
>>> @@ -200,6 +201,7 @@ const char * const cmd_inspect_dump_tree_usage[] = {
>>>       "-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)",
>>>       "--follow               use with -b, to show all children tree
>>> blocks of <block_num>",
>>> +    "--noscan               do not scan for the partner device(s)",
>>>       NULL
>>>   };
>>>   @@ -214,7 +216,7 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>>>       struct btrfs_disk_key disk_key;
>>>       struct btrfs_key found_key;
>>>       char uuidbuf[BTRFS_UUID_UNPARSED_SIZE];
>>> -    int ret;
>>> +    int ret = 0;
>>>       int slot;
>>>       int extent_only = 0;
>>>       int device_only = 0;
>>> @@ -222,6 +224,7 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>>>       int roots_only = 0;
>>>       int root_backups = 0;
>>>       int traverse = BTRFS_PRINT_TREE_DEFAULT;
>>> +    int dev_optind;
>>>       unsigned open_ctree_flags;
>>>       u64 block_only = 0;
>>>       struct btrfs_root *tree_root_scan;
>>> @@ -239,8 +242,8 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>>>       optind = 0;
>>>       while (1) {
>>>           int c;
>>> -        enum { GETOPT_VAL_FOLLOW = 256, GETOPT_VAL_DFS,
>>> -               GETOPT_VAL_BFS };
>>> +        enum { GETOPT_VAL_FOLLOW = 256, GETOPT_VAL_DFS, GETOPT_VAL_BFS,
>>> +               GETOPT_VAL_NOSCAN};
>>>           static const struct option long_options[] = {
>>>               { "extents", no_argument, NULL, 'e'},
>>>               { "device", no_argument, NULL, 'd'},
>>> @@ -252,6 +255,7 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>>>               { "follow", no_argument, NULL, GETOPT_VAL_FOLLOW },
>>>               { "bfs", no_argument, NULL, GETOPT_VAL_BFS },
>>>               { "dfs", no_argument, NULL, GETOPT_VAL_DFS },
>>> +            { "noscan", no_argument, NULL, GETOPT_VAL_NOSCAN },
>>>               { NULL, 0, NULL, 0 }
>>>           };
>>>   @@ -313,24 +317,49 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>>>           case GETOPT_VAL_BFS:
>>>               traverse = BTRFS_PRINT_TREE_BFS;
>>>               break;
>>> +        case GETOPT_VAL_NOSCAN:
>>> +            open_ctree_flags |= OPEN_CTREE_NO_DEVICES;  <--- [1]
>>> +            break;
>>>           default:
>>>               usage(cmd_inspect_dump_tree_usage);
>>>           }
>>>       }
>>>   -    if (check_argc_exact(argc - optind, 1))
>>> +    if (check_argc_min(argc - optind, 1))
>>>           usage(cmd_inspect_dump_tree_usage);
>>>   -    ret = check_arg_type(argv[optind]);
>>> -    if (ret != BTRFS_ARG_BLKDEV && ret != BTRFS_ARG_REG) {
>>> -        if (ret < 0) {
>>> -            errno = -ret;
>>> -            error("invalid argument %s: %m", argv[optind]);
>>> -        } else {
>>> -            error("not a block device or regular file: %s",
>>> -                  argv[optind]);
>>> +    dev_optind = optind;
>>> +    while (dev_optind < argc) {
>>> +        int fd;
>>> +        struct btrfs_fs_devices *fs_devices;
>>> +        u64 num_devices;
>>> +
>>> +        ret = check_arg_type(argv[optind]);
>>> +        if (ret != BTRFS_ARG_BLKDEV && ret != BTRFS_ARG_REG) {
>>> +            if (ret < 0) {
>>> +                errno = -ret;
>>> +                error("invalid argument %s: %m", argv[dev_optind]);
>>> +            } else {
>>> +                error("not a block device or regular file: %s",
>>> +                       argv[dev_optind]);
>>> +            }
>>>           }
>>> -        goto out;
>>> +        fd = open(argv[dev_optind], O_RDONLY);
>>> +        if (fd < 0) {
>>> +            error("cannot open %s: %m", argv[dev_optind]);
>>> +            return -EINVAL;
>>> +        }
>>> +        ret = btrfs_scan_one_device(fd, argv[dev_optind], &fs_devices,
>>> +                        &num_devices,
>>> +                        BTRFS_SUPER_INFO_OFFSET,
>>> +                        SBREAD_DEFAULT);
>>> +        close(fd);
>>> +        if (ret) {
>>> +            error("device scan %s: %s", argv[dev_optind],
>>> +                   strerror(-ret));
>>> +            return ret;
>>> +        }
>>> +        dev_optind++;
>>>       }
>>>         printf("%s\n", PACKAGE_STRING);
>>>
> 

Re: [PATCH v4] btrfs-progs: dump-tree: add noscan option

[Su Yue]

On 2019/2/28 2:54 PM, Anand Jain wrote:
> From: Anand Jain <Anand.Jain@oracle.com>
> 
> There is no way to dump tree from a disk in the degraded mode.
> Such as, when you specify a device for the cli 'btrfs inspect
> dump-tree /dev/sda' it would invariably scan for its partner devices
> to built and print the tree. This approach at times defeats the purpose.
> Suppose in RAID1 if you want to review each mirror separately as of now
> there is no way you can do that. So this patch adds an option --noscan
> for example:
>    'btrfs inspect dump-tree --noscan <dev> [<dev>..]'
> with which it shall not scan for the other devices to report the tree, and
> helps debug RAID1s.
> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> v3->v4: change the patch title.
> 	collapse scan_args() to its only parent cmd_inspect_dump_tree()
> 	(it was bit confusing).
> 	update the change log.
> 	update usage.
> 	update man page.
> v2->v3: make it scalable for more than two disks in noscan mode
> v1->v2: rename --degraded to --noscan
> ---
>   Documentation/btrfs-inspect-internal.asciidoc |  5 ++-
>   cmds-inspect-dump-tree.c                      | 57 ++++++++++++++++++++-------
>   2 files changed, 47 insertions(+), 15 deletions(-)
> 
> diff --git a/Documentation/btrfs-inspect-internal.asciidoc b/Documentation/btrfs-inspect-internal.asciidoc
> index 381497d284b8..f9d7f1c58f00 100644
> --- a/Documentation/btrfs-inspect-internal.asciidoc
> +++ b/Documentation/btrfs-inspect-internal.asciidoc
> @@ -61,7 +61,7 @@ specify which mirror to print, valid values are 0, 1 and 2 and the superblock
>   must be present on the device with a valid signature, can be used together with
>   '--force'
>   
> -*dump-tree* [options] <device>::
> +*dump-tree* [options] <device> [device...]::
>   (replaces the standalone tool *btrfs-debug-tree*)
>   +
>   Dump tree structures from a given device in textual form, expand keys to human
> @@ -95,6 +95,9 @@ intermixed in the output
>   --bfs::::
>   use breadth-first search to print trees. the nodes are printed before all
>   leaves
> +--noscan::::
> +do not scan the system for other partner device(s), only use the device(s)
> +provided in the argument
>   -t <tree_id>::::
>   print only the tree with the specified ID, where the ID can be numerical or
>   common name in a flexible human readable form
> diff --git a/cmds-inspect-dump-tree.c b/cmds-inspect-dump-tree.c
> index ad5345b4f1db..9dd040e5de17 100644
> --- a/cmds-inspect-dump-tree.c
> +++ b/cmds-inspect-dump-tree.c
> @@ -21,6 +21,7 @@
>   #include <unistd.h>
>   #include <uuid/uuid.h>
>   #include <getopt.h>
> +#include <fcntl.h>
>   
>   #include "kerncompat.h"
>   #include "radix-tree.h"
> @@ -185,7 +186,7 @@ static u64 treeid_from_string(const char *str, const char **end)
>   }
>   
>   const char * const cmd_inspect_dump_tree_usage[] = {
> -	"btrfs inspect-internal dump-tree [options] device",
> +	"btrfs inspect-internal dump-tree [options] <device> [<device> ..]",
>   	"Dump tree structures from a given device",
>   	"Dump tree structures from a given device in textual form, expand keys to human",
>   	"readable equivalents where possible.",
> @@ -200,6 +201,7 @@ const char * const cmd_inspect_dump_tree_usage[] = {
>   	"-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)",
>   	"--follow               use with -b, to show all children tree blocks of <block_num>",
> +	"--noscan               do not scan for the partner device(s)",
>   	NULL
>   };
>   
> @@ -214,7 +216,7 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>   	struct btrfs_disk_key disk_key;
>   	struct btrfs_key found_key;
>   	char uuidbuf[BTRFS_UUID_UNPARSED_SIZE];
> -	int ret;
> +	int ret = 0;
>   	int slot;
>   	int extent_only = 0;
>   	int device_only = 0;
> @@ -222,6 +224,7 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>   	int roots_only = 0;
>   	int root_backups = 0;
>   	int traverse = BTRFS_PRINT_TREE_DEFAULT;
> +	int dev_optind;
>   	unsigned open_ctree_flags;
>   	u64 block_only = 0;
>   	struct btrfs_root *tree_root_scan;
> @@ -239,8 +242,8 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>   	optind = 0;
>   	while (1) {
>   		int c;
> -		enum { GETOPT_VAL_FOLLOW = 256, GETOPT_VAL_DFS,
> -		       GETOPT_VAL_BFS };
> +		enum { GETOPT_VAL_FOLLOW = 256, GETOPT_VAL_DFS, GETOPT_VAL_BFS,
> +		       GETOPT_VAL_NOSCAN};
>   		static const struct option long_options[] = {
>   			{ "extents", no_argument, NULL, 'e'},
>   			{ "device", no_argument, NULL, 'd'},
> @@ -252,6 +255,7 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>   			{ "follow", no_argument, NULL, GETOPT_VAL_FOLLOW },
>   			{ "bfs", no_argument, NULL, GETOPT_VAL_BFS },
>   			{ "dfs", no_argument, NULL, GETOPT_VAL_DFS },
> +			{ "noscan", no_argument, NULL, GETOPT_VAL_NOSCAN },
>   			{ NULL, 0, NULL, 0 }
>   		};
>   
> @@ -313,24 +317,49 @@ int cmd_inspect_dump_tree(int argc, char **argv)
>   		case GETOPT_VAL_BFS:
>   			traverse = BTRFS_PRINT_TREE_BFS;
>   			break;
> +		case GETOPT_VAL_NOSCAN:
> +			open_ctree_flags |= OPEN_CTREE_NO_DEVICES;
> +			break;
>   		default:
>   			usage(cmd_inspect_dump_tree_usage);
>   		}
>   	}
>   
> -	if (check_argc_exact(argc - optind, 1))
> +	if (check_argc_min(argc - optind, 1))
>   		usage(cmd_inspect_dump_tree_usage);
>   
> -	ret = check_arg_type(argv[optind]);
> -	if (ret != BTRFS_ARG_BLKDEV && ret != BTRFS_ARG_REG) {
> -		if (ret < 0) {
> -			errno = -ret;
> -			error("invalid argument %s: %m", argv[optind]);
> -		} else {
> -			error("not a block device or regular file: %s",
> -			      argv[optind]);
> +	dev_optind = optind;
> +	while (dev_optind < argc) {
> +		int fd;
> +		struct btrfs_fs_devices *fs_devices;
> +		u64 num_devices;
> +
> +		ret = check_arg_type(argv[optind]);
> +		if (ret != BTRFS_ARG_BLKDEV && ret != BTRFS_ARG_REG) {
> +			if (ret < 0) {
> +				errno = -ret;
> +				error("invalid argument %s: %m", argv[dev_optind]);
> +			} else {
> +				error("not a block device or regular file: %s",
> +				       argv[dev_optind]);
> +			}
>   		}
> -		goto out;
> +		fd = open(argv[dev_optind], O_RDONLY);
> +		if (fd < 0) {
> +			error("cannot open %s: %m", argv[dev_optind]);
> +			return -EINVAL;
> +		}
> +		ret = btrfs_scan_one_device(fd, argv[dev_optind], &fs_devices,
> +					    &num_devices,
> +					    BTRFS_SUPER_INFO_OFFSET,
> +					    SBREAD_DEFAULT);
> +		close(fd);
> +		if (ret) {
> +			error("device scan %s: %s", argv[dev_optind],
> +			       strerror(-ret));

Nit:

Should do some change to follow current "%m" style?

Thanks
Su
> +			return ret;
> +		}
> +		dev_optind++;
>   	}
>   
>   	printf("%s\n", PACKAGE_STRING);
> 

Re: [PATCH v4] btrfs-progs: dump-tree: add noscan option

[Anand Jain]

>> +        if (ret) {
>> +            error("device scan %s: %s", argv[dev_optind],
>> +                   strerror(-ret));
> 
> Nit:
> 
> Should do some change to follow current "%m" style?
> 
> Thanks
> Su

  Ok will change it. Thanks for catching.

Thanks, Anand