diff mbox

[3/3] btrfs-progs: use BTRFS_SCAN_BACKUP_SB flag in btrfs_scan_one_device

Message ID 1362756300-30212-4-git-send-email-anand.jain@oracle.com (mailing list archive)
State Under Review, archived
Headers show

Commit Message

Anand Jain March 8, 2013, 3:25 p.m. UTC 
bug:
-------
mkfs.btrfs /dev/sdb -f && yes| mkfs.ext4 /dev/sdb && mount /dev/sdb /ext4
mkfs.btrfs -f /dev/sdc /dev/sdd (run twice)
mkfs.btrfs -f /dev/sdc /dev/sdd
::
ERROR: unable to scan the device '/dev/sdb' - Device or resource busy
ERROR: unable to scan the device '/dev/sdb' - Device or resource busy
adding device /dev/sdd id 2
fs created label (null) on /dev/sdc
	nodesize 4096 leafsize 4096 sectorsize 4096 size 3.11GB
--------

Since we run mkfs.btrfs twice above, there is already a stale
btrfs when mkfs.btrfs is run for the 2nd time. which kicks in
btrfs_scan_for_fsid() to perform a system-wide scan to find the
stale btrfs's partner (to check if that by any chance is mounted)
which in process comes across /dev/sdb. Now when it finds
/dev/sdb it finds that primary SB is not present and we need
to stop him there.
This is done by NOT setting BTRFS_SCAN_BACKUP_SB for the function
btrfs_scan_for_fsid(). To ensure rest of the logic is unaffected,
this patch will ensure BTRFS_SCAN_BACKUP_SB is set for all other
places except at check_mounted_where().

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 cmds-device.c     | 3 ++-
 cmds-filesystem.c | 2 +-
 cmds-replace.c    | 3 ++-
 disk-io.c         | 7 ++++---
 find-root.c       | 5 +++--
 utils.c           | 9 ++++++---
 volumes.c         | 4 ++--
 volumes.h         | 2 +-
 8 files changed, 21 insertions(+), 14 deletions(-)

Comments

Eric Sandeen March 11, 2013, 3:03 p.m. UTC | #1 
On 3/8/13 9:25 AM, Anand Jain wrote:
> bug:
> -------
> mkfs.btrfs /dev/sdb -f && yes| mkfs.ext4 /dev/sdb && mount /dev/sdb /ext4
> mkfs.btrfs -f /dev/sdc /dev/sdd (run twice)
> mkfs.btrfs -f /dev/sdc /dev/sdd
> ::
> ERROR: unable to scan the device '/dev/sdb' - Device or resource busy
> ERROR: unable to scan the device '/dev/sdb' - Device or resource busy
> adding device /dev/sdd id 2
> fs created label (null) on /dev/sdc
> 	nodesize 4096 leafsize 4096 sectorsize 4096 size 3.11GB
> --------
> 
> Since we run mkfs.btrfs twice above, there is already a stale
> btrfs when mkfs.btrfs is run for the 2nd time. which kicks in
> btrfs_scan_for_fsid() to perform a system-wide scan to find the
> stale btrfs's partner (to check if that by any chance is mounted)
> which in process comes across /dev/sdb. Now when it finds
> /dev/sdb it finds that primary SB is not present and we need
> to stop him there.
> This is done by NOT setting BTRFS_SCAN_BACKUP_SB for the function
> btrfs_scan_for_fsid(). To ensure rest of the logic is unaffected,
> this patch will ensure BTRFS_SCAN_BACKUP_SB is set for all other
> places except at check_mounted_where().

Thanks, this seems like progress in the right direction.

But that means that many other paths will still scan backups, right?

In the following case sdb1 is an ext4-mounted partition w/ a stale btrfs
backup superblock present in the middle.

# mount /dev/sdb1 /mnt/test
# mount | grep sdb1
/dev/sdb1 on /mnt/test type ext4 (rw)

# btrfs device scan /dev/sdb1
Scanning for Btrfs filesystems in '/dev/sdb1'
ERROR: unable to scan the device '/dev/sdb1' - Device or resource busy

Perhaps this is ok since we explicitly told it to scan an
ext4-mounted device.

[[But, then if I unmount it:

# btrfs device scan /dev/sdb1
Scanning for Btrfs filesystems in '/dev/sdb1'
ERROR: unable to scan the device '/dev/sdb1' - Invalid argument

weird, not sure where that came from.  :(  Unrelated to this question
though.]]

Also:

# btrfs filesystem show /dev/sdb1
Label: none  uuid: a96ea6e6-d3d5-444d-9aaf-057ec579dffe
	Total devices 1 FS bytes used 28.00KB
	devid    1 size 4.00GB used 445.50MB path /dev/sdb1

whoa, ok, so it's a currently mounted ext4 device, but filesystem
show tells me it's btrfs?

How about this one:
# mount /dev/sdb1 /mnt/test
# mount | grep sdb1
/dev/sdb1 on /mnt/test type ext4 (rw)

# btrfs check /dev/sdb1
Checking filesystem on /dev/sdb1
UUID: a96ea6e6-d3d5-444d-9aaf-057ec579dffe
checking extents
checking fs roots
checking root refs
found 28672 bytes used err is 0
total csum bytes: 0
total tree bytes: 28672
total fs tree bytes: 8192
btree space waste bytes: 22875
file data blocks allocated: 0
 referenced 0
Btrfs v0.20-rc1-194-g3deeb4c

So my mountged ext4 fs is also a perfectly consistent btrfs fs?

and I think the list goes on.

IMHO, nothing should be checking the backup superblocks unless explicitly
told to.  i.e. in e2fsprogs, e2fsck has:

       -b superblock
              Instead  of using the normal superblock, use an alternative
              superblock specified by superblock.

and debugfs has:

       -s superblock
              Causes the file system superblock to be read from the given
              block  number,  instead  of  using  the  primary superblock

I think the backups need to be used for explicit recovery (and maybe to
be checked once the primary has been confirmed) and never used during any
normal operation, if the first one is found to be missing.

-Eric



> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> ---
>  cmds-device.c     | 3 ++-
>  cmds-filesystem.c | 2 +-
>  cmds-replace.c    | 3 ++-
>  disk-io.c         | 7 ++++---
>  find-root.c       | 5 +++--
>  utils.c           | 9 ++++++---
>  volumes.c         | 4 ++--
>  volumes.h         | 2 +-
>  8 files changed, 21 insertions(+), 14 deletions(-)
> 
> diff --git a/cmds-device.c b/cmds-device.c
> index 1b8f378..9447e7f 100644
> --- a/cmds-device.c
> +++ b/cmds-device.c
> @@ -203,7 +203,8 @@ static int cmd_scan_dev(int argc, char **argv)
>  
>  		printf("Scanning for Btrfs filesystems\n");
>  		if(checklist)
> -			ret = btrfs_scan_block_devices(BTRFS_SCAN_REGISTER);
> +			ret = btrfs_scan_block_devices(BTRFS_SCAN_REGISTER|
> +						       BTRFS_SCAN_BACKUP_SB);
>  		else
>  			ret = btrfs_scan_one_dir("/dev", BTRFS_SCAN_REGISTER);
>  		if (ret){
> diff --git a/cmds-filesystem.c b/cmds-filesystem.c
> index 2210020..d2e708d 100644
> --- a/cmds-filesystem.c
> +++ b/cmds-filesystem.c
> @@ -257,7 +257,7 @@ static int cmd_show(int argc, char **argv)
>  		usage(cmd_show_usage);
>  
>  	if(checklist)
> -		ret = btrfs_scan_block_devices(0);
> +		ret = btrfs_scan_block_devices(BTRFS_SCAN_BACKUP_SB);
>  	else
>  		ret = btrfs_scan_one_dir("/dev", 0);
>  
> diff --git a/cmds-replace.c b/cmds-replace.c
> index 4cc32df..f6e1619 100644
> --- a/cmds-replace.c
> +++ b/cmds-replace.c
> @@ -275,7 +275,8 @@ static int cmd_start_replace(int argc, char **argv)
>  		goto leave_with_error;
>  	}
>  	ret = btrfs_scan_one_device(fddstdev, dstdev, &fs_devices_mnt,
> -				    &total_devs, BTRFS_SUPER_INFO_OFFSET);
> +				    &total_devs, BTRFS_SUPER_INFO_OFFSET,
> +				    BTRFS_SCAN_BACKUP_SB);
>  	if (ret >= 0 && !force_using_targetdev) {
>  		fprintf(stderr,
>  			"Error, target device %s contains filesystem, use '-f' to force overwriting.\n",
> diff --git a/disk-io.c b/disk-io.c
> index 33e7e78..914b567 100644
> --- a/disk-io.c
> +++ b/disk-io.c
> @@ -825,7 +825,8 @@ static struct btrfs_fs_info *__open_ctree_fd(int fp, const char *path,
>  	posix_fadvise(fp, 0, 0, POSIX_FADV_DONTNEED);
>  
>  	ret = btrfs_scan_one_device(fp, path, &fs_devices,
> -				    &total_devs, sb_bytenr);
> +				    &total_devs, sb_bytenr,
> +				    BTRFS_SCAN_BACKUP_SB);
>  
>  	if (ret) {
>  		fprintf(stderr, "No valid Btrfs found on %s\n", path);
> @@ -834,7 +835,7 @@ static struct btrfs_fs_info *__open_ctree_fd(int fp, const char *path,
>  
>  	if (total_devs != 1) {
>  		ret = btrfs_scan_for_fsid(fs_devices, total_devs,
> -			BTRFS_SCAN_REGISTER);
> +			BTRFS_SCAN_REGISTER|BTRFS_SCAN_BACKUP_SB);
>  		if (ret)
>  			goto out;
>  	}
> @@ -1102,7 +1103,7 @@ struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr,
>  }
>  
>  int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr,
> -	u64 flags)
> +			 u64 flags)
>  {
>  	u8 fsid[BTRFS_FSID_SIZE];
>  	int fsid_is_initialized = 0;
> diff --git a/find-root.c b/find-root.c
> index c76de2b..40cacf1 100644
> --- a/find-root.c
> +++ b/find-root.c
> @@ -102,7 +102,8 @@ static struct btrfs_root *open_ctree_broken(int fd, const char *device)
>  	u64 features;
>  
>  	ret = btrfs_scan_one_device(fd, device, &fs_devices,
> -				    &total_devs, BTRFS_SUPER_INFO_OFFSET);
> +				    &total_devs, BTRFS_SUPER_INFO_OFFSET,
> +				    BTRFS_SCAN_BACKUP_SB);
>  
>  	if (ret) {
>  		fprintf(stderr, "No valid Btrfs found on %s\n", device);
> @@ -111,7 +112,7 @@ static struct btrfs_root *open_ctree_broken(int fd, const char *device)
>  
>  	if (total_devs != 1) {
>  		ret = btrfs_scan_for_fsid(fs_devices, total_devs,
> -			BTRFS_SCAN_REGISTER);
> +			BTRFS_SCAN_REGISTER|BTRFS_SCAN_BACKUP_SB);
>  		if (ret)
>  			goto out;
>  	}
> diff --git a/utils.c b/utils.c
> index feee572..95dee29 100644
> --- a/utils.c
> +++ b/utils.c
> @@ -835,7 +835,8 @@ int check_mounted_where(int fd, const char *file, char *where, int size,
>  
>  	/* scan the initial device */
>  	ret = btrfs_scan_one_device(fd, file, &fs_devices_mnt,
> -				    &total_devs, BTRFS_SUPER_INFO_OFFSET);
> +				    &total_devs, BTRFS_SUPER_INFO_OFFSET,
> +				    BTRFS_SCAN_BACKUP_SB);
>  	is_btrfs = (ret >= 0);
>  
>  	/* scan other devices */
> @@ -1032,7 +1033,8 @@ again:
>  		}
>  		ret = btrfs_scan_one_device(fd, fullpath, &tmp_devices,
>  					    &num_devices,
> -					    BTRFS_SUPER_INFO_OFFSET);
> +					    BTRFS_SUPER_INFO_OFFSET,
> +					    BTRFS_SCAN_BACKUP_SB);
>  		if (ret == 0 && flags & BTRFS_SCAN_REGISTER) {
>  			btrfs_register_one_device(fullpath);
>  		}
> @@ -1361,7 +1363,8 @@ scan_again:
>  		}
>  		ret = btrfs_scan_one_device(fd, fullpath, &tmp_devices,
>  					    &num_devices,
> -					    BTRFS_SUPER_INFO_OFFSET);
> +					    BTRFS_SUPER_INFO_OFFSET,
> +					    flags);
>  		if (ret == 0 && flags & BTRFS_SCAN_REGISTER) {
>  			btrfs_register_one_device(fullpath);
>  		}
> diff --git a/volumes.c b/volumes.c
> index b6e3f29..e1795e3 100644
> --- a/volumes.c
> +++ b/volumes.c
> @@ -212,7 +212,7 @@ fail:
>  
>  int btrfs_scan_one_device(int fd, const char *path,
>  			  struct btrfs_fs_devices **fs_devices_ret,
> -			  u64 *total_devs, u64 super_offset)
> +			  u64 *total_devs, u64 super_offset, u64 flags)
>  {
>  	struct btrfs_super_block *disk_super;
>  	char *buf;
> @@ -227,7 +227,7 @@ int btrfs_scan_one_device(int fd, const char *path,
>  	}
>  	disk_super = (struct btrfs_super_block *)buf;
>  	ret = btrfs_read_dev_super(fd, disk_super, super_offset,
> -		BTRFS_SCAN_BACKUP_SB);
> +				flags);
>  	if (ret < 0) {
>  		ret = -EIO;
>  		goto error_brelse;
> diff --git a/volumes.h b/volumes.h
> index 911f788..f87aa5b 100644
> --- a/volumes.h
> +++ b/volumes.h
> @@ -179,7 +179,7 @@ int btrfs_update_device(struct btrfs_trans_handle *trans,
>  			struct btrfs_device *device);
>  int btrfs_scan_one_device(int fd, const char *path,
>  			  struct btrfs_fs_devices **fs_devices_ret,
> -			  u64 *total_devs, u64 super_offset);
> +			  u64 *total_devs, u64 super_offset, u64 flags);
>  int btrfs_num_copies(struct btrfs_mapping_tree *map_tree, u64 logical, u64 len);
>  int btrfs_bootstrap_super_map(struct btrfs_mapping_tree *map_tree,
>  			      struct btrfs_fs_devices *fs_devices);
> 

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David Sterba March 11, 2013, 6:16 p.m. UTC | #2 
On Mon, Mar 11, 2013 at 10:03:46AM -0500, Eric Sandeen wrote:
> IMHO, nothing should be checking the backup superblocks unless explicitly
> told to.

That's the whole point I believe.

update the infrastructure, every SB access looks to the first copy
unless told by command line options.


david
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Anand Jain March 13, 2013, 11:46 a.m. UTC | #3 
Thanks Eric and David.

  I have sent out V3 patch-set which will disable access
  to backup super-block unless requested by the user.

  here below are some test cases and results before and
  after this fix.. which finds the patch works awesome.


--------
the original problem which all this started..

mkfs.btrfs /dev/sdb -f && yes| mkfs.ext4 /dev/sdb && mount /dev/sdb /ext4
~/before/mkfs.btrfs -f /dev/sdc /dev/sdd (run twice)
~/before/mkfs.btrfs -f /dev/sdc /dev/sdd
::
ERROR: unable to scan the device '/dev/sdb' - Device or resource busy
ERROR: unable to scan the device '/dev/sdb' - Device or resource busy
adding device /dev/sdd id 2
fs created label (null) on /dev/sdc
         nodesize 4096 leafsize 4096 sectorsize 4096 size 3.11GB


after the fix.

# mkfs.btrfs -f /dev/sdc /dev/sdd

WARNING! - Btrfs v0.20-rc1-238-g170881a-dirty IS EXPERIMENTAL
WARNING! - see http://btrfs.wiki.kernel.org before using

adding device /dev/sdd id 2
fs created label (null) on /dev/sdc
	nodesize 4096 leafsize 4096 sectorsize 4096 size 104.98GB
Btrfs v0.20-rc1-238-g170881a-dirty
-------------

# umount /ext4

# mkfs.btrfs /dev/sdb /dev/sdc -f && wipefs /dev/sdb

There is an existing bug..

# ~/before/btrfs check /dev/sdc --repair
enabling repair mode
warning, device 1 is missing
warning, device 1 is missing
warning devid 1 not found already
Checking filesystem on /dev/sdc
UUID: e03c477d-b696-46c1-bf79-43b8b8454f11
checking extents
checking fs roots
checking root refs
btrfs: extent-tree.c:2553: btrfs_reserve_extent: Assertion `!(ret)' failed.
Aborted (core dumped)
#

and its still there even after this patch :-)

# btrfs check /dev/sdc --repair
enabling repair mode
warning, device 1 is missing
warning, device 1 is missing
warning devid 1 not found already
Checking filesystem on /dev/sdc
UUID: e03c477d-b696-46c1-bf79-43b8b8454f11
checking extents
checking fs roots
checking root refs
btrfs: extent-tree.c:2553: btrfs_reserve_extent: Assertion `!(ret)' failed.
Aborted (core dumped)

-------------------------


# mkfs.btrfs /dev/sdb /dev/sdc -f && yes|mkfs.ext4 /dev/sdb

without the fix
# ~/before/btrfs restore -o /dev/sdb ~/tmp
ERROR: device scan failed '/dev/sdb' - Invalid argument
ERROR: device scan failed '/dev/sdb' - Invalid argument
Root objectid is 5

with the fix

# btrfs restore -o /dev/sdb ~/tmp
No valid Btrfs found on /dev/sdb
Could not open root, trying backup super
Root objectid is 5

now I say to use sb backup 1..

# btrfs restore -u 1 -o /dev/sdb ~/tmp
Root objectid is 5
# echo $?
0

--------------

# mkfs.btrfs /dev/sdb /dev/sdc -f && yes|mkfs.ext4 /dev/sdb

# ~/before/btrfs check /dev/sdc --repair
enabling repair mode
ERROR: device scan failed '/dev/sdb' - Invalid argument
ERROR: device scan failed '/dev/sdb' - Invalid argument
Checking filesystem on /dev/sdc
UUID: 5dc5c663-eeea-4ec2-b8fe-170157f5d68d
checking extents
checking fs roots
checking root refs
found 28672 bytes used err is 0
total csum bytes: 0
total tree bytes: 28672
total fs tree bytes: 8192
btree space waste bytes: 22420
file data blocks allocated: 0
  referenced 0
Btrfs v0.20-rc1-235-gdd21bc1

# mkfs.btrfs /dev/sdb /dev/sdc -f && yes|mkfs.ext4 /dev/sdb

since now new code doesn't read backup SB of devid1
it hits the earlier known bug.

# btrfs check /dev/sdc --repair
enabling repair mode
warning, device 1 is missing
warning, device 1 is missing
warning devid 1 not found already
Checking filesystem on /dev/sdc
UUID: daa0dc6d-35b6-43ab-8333-894710a5b917
checking extents
checking fs roots
checking root refs
btrfs: extent-tree.c:2553: btrfs_reserve_extent: Assertion `!(ret)' failed.
Aborted (core dumped)

So user would need to fix the devid1 first.

# btrfs check /dev/sdb --repair
enabling repair mode
No valid Btrfs found on /dev/sdb

# btrfs check -s 1 /dev/sdb --repair
using SB copy 1, bytenr 67108864
enabling repair mode
Checking filesystem on /dev/sdb
UUID: daa0dc6d-35b6-43ab-8333-894710a5b917
checking extents
checking fs roots
checking root refs
found 28672 bytes used err is 0
total csum bytes: 0
total tree bytes: 28672
total fs tree bytes: 8192
btree space waste bytes: 22420
file data blocks allocated: 0
  referenced 0
Btrfs v0.20-rc1-238-g170881a-dirty

# btrfs check /dev/sdc --repair
enabling repair mode
warning, device 1 is missing
warning, device 1 is missing
warning devid 1 not found already
Checking filesystem on /dev/sdc
UUID: daa0dc6d-35b6-43ab-8333-894710a5b917
checking extents
checking fs roots
checking root refs
btrfs: extent-tree.c:2553: btrfs_reserve_extent: Assertion `!(ret)' failed.
Aborted (core dumped)

Need to write back the backup SB to primary SB.
IMO when -s 1 was given it had the chance to fix
primary.. this can be fixed later.

# ./btrfs-select-super -s 1 /dev/sdb
using SB copy 1, bytenr 67108864
ERROR: device scan failed '/dev/sdb' - Invalid argument

# btrfs check /dev/sdc --repair
enabling repair mode
Checking filesystem on /dev/sdc
UUID: daa0dc6d-35b6-43ab-8333-894710a5b917
checking extents
checking fs roots
checking root refs
found 28672 bytes used err is 0
total csum bytes: 0
total tree bytes: 28672
total fs tree bytes: 8192
btree space waste bytes: 22420
file data blocks allocated: 0
  referenced 0
Btrfs v0.20-rc1-238-g170881a-dirty
---------------------------------------------------------------


I am not sure if I have a wipe -a working for btrfs,
so I would clean using dd.

# dd if=/dev/zero bs=1 count=8 of=/dev/sdb seek=$((64*1024+64))
8+0 records in
8+0 records out
8 bytes (8 B) copied, 0.000324503 s, 24.7 kB/s

# dd if=/dev/zero bs=1 count=8 of=/dev/sdb seek=$((64*1024*1024+64))
8+0 records in
8+0 records out
8 bytes (8 B) copied, 0.000364635 s, 21.9 kB/s

# dd if=/dev/zero bs=1 count=8 of=/dev/sdb seek=$((256*1024*1024*1024+64))
dd: `/dev/sdb': cannot seek: Invalid argument
0+0 records in
0+0 records out
0 bytes (0 B) copied, 0.000430846 s, 0.0 kB/s

This behavior is same before and after the patch.

# btrfs check /dev/sdb
No valid Btrfs found on /dev/sdb
# btrfs check /dev/sdb -s 1
using SB copy 1, bytenr 67108864
No valid Btrfs found on /dev/sdb
# btrfs check /dev/sdb -s 2
using SB copy 2, bytenr 274877906944
No valid Btrfs found on /dev/sdb
#
------------------------

  # mkfs.btrfs /dev/sdb /dev/sdc -f && mount /dev/sdc /btrfs

  # dd if=/dev/zero bs=1 count=8 of=/dev/sdb seek=$((64*1024+64))
  # dd if=/dev/zero bs=1 count=8 of=/dev/sdb seek=$((64*1024*1024+64))
  # dd if=/dev/zero bs=1 count=8 of=/dev/sdb seek=$((256*1024*1024*1024+64))

# mkfs.btrfs /dev/sdb

WARNING! - Btrfs v0.20-rc1-238-g170881a-dirty IS EXPERIMENTAL
WARNING! - see http://btrfs.wiki.kernel.org before using

/dev/sdb is mounted


# umount /btrfs

# mkfs.btrfs /dev/sdb

WARNING! - Btrfs v0.20-rc1-238-g170881a-dirty IS EXPERIMENTAL
WARNING! - see http://btrfs.wiki.kernel.org before using

/dev/sdb appears to contain an existing filesystem (btrfs).
Use the -f option to force overwrite.
#

-------------------------


# mkfs.btrfs /dev/sdd /dev/sde -f

WARNING! - Btrfs v0.20-rc1-238-g170881a-dirty IS EXPERIMENTAL
WARNING! - see http://btrfs.wiki.kernel.org before using

adding device /dev/sde id 2
fs created label (null) on /dev/sdd
	nodesize 4096 leafsize 4096 sectorsize 4096 size 93.22GB
Btrfs v0.20-rc1-238-g170881a-dirty
# mount /dev/sde /btrfs
# umount /btrfs
# dd if=/dev/zero bs=1 count=8 of=/dev/sde seek=$((64*1024+64))
8+0 records in
8+0 records out
8 bytes (8 B) copied, 0.0149415 s, 0.5 kB/s

remove /dev/sdd

# x="0 0 3 0"
# echo "scsi remove-single-device $x" > /proc/scsi/scsi
# lsscsi
[0:0:0:0]    disk    Sun      boot1            V1.0  /dev/sda
[0:0:2:0]    disk    Sun      boot3            V1.0  /dev/sdc
[0:0:4:0]    disk    Sun      boot5            V1.0  /dev/sde
[0:1:0:0]    disk    SEAGATE  ST914602SSUN146G 0603  -
[0:1:1:0]    disk    SEAGATE  ST914602SSUN146G 0603  -
[0:3:0:0]    enclosu ADAPTEC  Virtual SGPIO  0 0001  -


# btrfs check /dev/sde
No valid Btrfs found on /dev/sde

# btrfs check /dev/sde -s 1
using SB copy 1, bytenr 67108864
warning, device 1 is missing
warning, device 1 is missing
warning devid 1 not found already
Checking filesystem on /dev/sde
UUID: fa08122d-832f-4f32-87ee-58eb9380d5da
checking extents
checking fs roots
checking root refs
found 815104 bytes used err is 0
total csum bytes: 0
total tree bytes: 28672
total fs tree bytes: 8192
btree space waste bytes: 21476
file data blocks allocated: 786432
  referenced 786432
Btrfs v0.20-rc1-238-g170881a-dirty

# ./btrfs-select-super -s 1 /dev/sde
using SB copy 1, bytenr 67108864
ERROR: device scan failed '/dev/sdc' - Invalid argument
warning, device 1 is missing
warning, device 1 is missing
warning devid 1 not found already

# btrfs check /dev/sde
warning, device 1 is missing
warning, device 1 is missing
warning devid 1 not found already
Checking filesystem on /dev/sde
UUID: fa08122d-832f-4f32-87ee-58eb9380d5da
checking extents
checking fs roots
checking root refs
found 815104 bytes used err is 0
total csum bytes: 0
total tree bytes: 28672
total fs tree bytes: 8192
btree space waste bytes: 21476
file data blocks allocated: 786432
  referenced 786432
Btrfs v0.20-rc1-238-g170881a-dirty
#
---------------


Thanks, Anand


On 03/12/2013 02:16 AM, David Sterba wrote:
> On Mon, Mar 11, 2013 at 10:03:46AM -0500, Eric Sandeen wrote:
>> IMHO, nothing should be checking the backup superblocks unless explicitly
>> told to.
>
> That's the whole point I believe.
>
> update the infrastructure, every SB access looks to the first copy
> unless told by command line options.
>
>
> david
> --
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Anand Jain March 14, 2013, 8:51 a.m. UTC | #4 
just for the record, this patch also fixes the following 2 issues..

  sdc contains primary-SB of ext4 and backup SB of btrfs

# blkid /dev/sdc
/dev/sdc: UUID="4450e281-db04-4736-a03e-1ce6deda74f3" TYPE="ext4"
#

# btrfs-show-super -i 1 /dev/sdc
superblock: bytenr=67108864, device=/dev/sdc
::

----
# ~/before/btrfs dev scan
Scanning for Btrfs filesystems
ERROR: device scan failed '/dev/sdc' - Invalid argument

# btrfs dev scan
Scanning for Btrfs filesystems
----

-----
# ~/before/btrfs fi show
::

Label: none  uuid: aa8b3f0c-3ade-490a-a35d-dd62dbd9cc07
	Total devices 2 FS bytes used 796.00KB
	devid    2 size 59.99GB used 2.01GB path /dev/sdc
	*** Some devices missing
::
Btrfs v0.20-rc1-235-gdd21bc1
#


# btrfs fi show
Label: none  uuid: 0d690e00-a34f-4c6b-9660-c6b1b6684ecc
	Total devices 1 FS bytes used 28.00KB
	devid    1 size 59.99GB used 2.04GB path /dev/sdb

Label: none  uuid: fa08122d-832f-4f32-87ee-58eb9380d5da
	Total devices 2 FS bytes used 796.00KB
	devid    2 size 48.23GB used 2.01GB path /dev/sde
	devid    1 size 44.99GB used 2.03GB path /dev/sdd

Btrfs v0.20-rc1-238-g5d571b4-dirty
-----

Thanks, Anand


On 03/13/2013 07:46 PM, Anand Jain wrote:
>
>
> Thanks Eric and David.
>
>   I have sent out V3 patch-set which will disable access
>   to backup super-block unless requested by the user.
>
>   here below are some test cases and results before and
>   after this fix.. which finds the patch works awesome.
>
>
> --------
> the original problem which all this started..
>
> mkfs.btrfs /dev/sdb -f && yes| mkfs.ext4 /dev/sdb && mount /dev/sdb /ext4
> ~/before/mkfs.btrfs -f /dev/sdc /dev/sdd (run twice)
> ~/before/mkfs.btrfs -f /dev/sdc /dev/sdd
> ::
> ERROR: unable to scan the device '/dev/sdb' - Device or resource busy
> ERROR: unable to scan the device '/dev/sdb' - Device or resource busy
> adding device /dev/sdd id 2
> fs created label (null) on /dev/sdc
>          nodesize 4096 leafsize 4096 sectorsize 4096 size 3.11GB
>
>
> after the fix.
>
> # mkfs.btrfs -f /dev/sdc /dev/sdd
>
> WARNING! - Btrfs v0.20-rc1-238-g170881a-dirty IS EXPERIMENTAL
> WARNING! - see http://btrfs.wiki.kernel.org before using
>
> adding device /dev/sdd id 2
> fs created label (null) on /dev/sdc
>      nodesize 4096 leafsize 4096 sectorsize 4096 size 104.98GB
> Btrfs v0.20-rc1-238-g170881a-dirty
> -------------
>
> # umount /ext4
>
> # mkfs.btrfs /dev/sdb /dev/sdc -f && wipefs /dev/sdb
>
> There is an existing bug..
>
> # ~/before/btrfs check /dev/sdc --repair
> enabling repair mode
> warning, device 1 is missing
> warning, device 1 is missing
> warning devid 1 not found already
> Checking filesystem on /dev/sdc
> UUID: e03c477d-b696-46c1-bf79-43b8b8454f11
> checking extents
> checking fs roots
> checking root refs
> btrfs: extent-tree.c:2553: btrfs_reserve_extent: Assertion `!(ret)' failed.
> Aborted (core dumped)
> #
>
> and its still there even after this patch :-)
>
> # btrfs check /dev/sdc --repair
> enabling repair mode
> warning, device 1 is missing
> warning, device 1 is missing
> warning devid 1 not found already
> Checking filesystem on /dev/sdc
> UUID: e03c477d-b696-46c1-bf79-43b8b8454f11
> checking extents
> checking fs roots
> checking root refs
> btrfs: extent-tree.c:2553: btrfs_reserve_extent: Assertion `!(ret)' failed.
> Aborted (core dumped)
>
> -------------------------
>
>
> # mkfs.btrfs /dev/sdb /dev/sdc -f && yes|mkfs.ext4 /dev/sdb
>
> without the fix
> # ~/before/btrfs restore -o /dev/sdb ~/tmp
> ERROR: device scan failed '/dev/sdb' - Invalid argument
> ERROR: device scan failed '/dev/sdb' - Invalid argument
> Root objectid is 5
>
> with the fix
>
> # btrfs restore -o /dev/sdb ~/tmp
> No valid Btrfs found on /dev/sdb
> Could not open root, trying backup super
> Root objectid is 5
>
> now I say to use sb backup 1..
>
> # btrfs restore -u 1 -o /dev/sdb ~/tmp
> Root objectid is 5
> # echo $?
> 0
>
> --------------
>
> # mkfs.btrfs /dev/sdb /dev/sdc -f && yes|mkfs.ext4 /dev/sdb
>
> # ~/before/btrfs check /dev/sdc --repair
> enabling repair mode
> ERROR: device scan failed '/dev/sdb' - Invalid argument
> ERROR: device scan failed '/dev/sdb' - Invalid argument
> Checking filesystem on /dev/sdc
> UUID: 5dc5c663-eeea-4ec2-b8fe-170157f5d68d
> checking extents
> checking fs roots
> checking root refs
> found 28672 bytes used err is 0
> total csum bytes: 0
> total tree bytes: 28672
> total fs tree bytes: 8192
> btree space waste bytes: 22420
> file data blocks allocated: 0
>   referenced 0
> Btrfs v0.20-rc1-235-gdd21bc1
>
> # mkfs.btrfs /dev/sdb /dev/sdc -f && yes|mkfs.ext4 /dev/sdb
>
> since now new code doesn't read backup SB of devid1
> it hits the earlier known bug.
>
> # btrfs check /dev/sdc --repair
> enabling repair mode
> warning, device 1 is missing
> warning, device 1 is missing
> warning devid 1 not found already
> Checking filesystem on /dev/sdc
> UUID: daa0dc6d-35b6-43ab-8333-894710a5b917
> checking extents
> checking fs roots
> checking root refs
> btrfs: extent-tree.c:2553: btrfs_reserve_extent: Assertion `!(ret)' failed.
> Aborted (core dumped)
>
> So user would need to fix the devid1 first.
>
> # btrfs check /dev/sdb --repair
> enabling repair mode
> No valid Btrfs found on /dev/sdb
>
> # btrfs check -s 1 /dev/sdb --repair
> using SB copy 1, bytenr 67108864
> enabling repair mode
> Checking filesystem on /dev/sdb
> UUID: daa0dc6d-35b6-43ab-8333-894710a5b917
> checking extents
> checking fs roots
> checking root refs
> found 28672 bytes used err is 0
> total csum bytes: 0
> total tree bytes: 28672
> total fs tree bytes: 8192
> btree space waste bytes: 22420
> file data blocks allocated: 0
>   referenced 0
> Btrfs v0.20-rc1-238-g170881a-dirty
>
> # btrfs check /dev/sdc --repair
> enabling repair mode
> warning, device 1 is missing
> warning, device 1 is missing
> warning devid 1 not found already
> Checking filesystem on /dev/sdc
> UUID: daa0dc6d-35b6-43ab-8333-894710a5b917
> checking extents
> checking fs roots
> checking root refs
> btrfs: extent-tree.c:2553: btrfs_reserve_extent: Assertion `!(ret)' failed.
> Aborted (core dumped)
>
> Need to write back the backup SB to primary SB.
> IMO when -s 1 was given it had the chance to fix
> primary.. this can be fixed later.
>
> # ./btrfs-select-super -s 1 /dev/sdb
> using SB copy 1, bytenr 67108864
> ERROR: device scan failed '/dev/sdb' - Invalid argument
>
> # btrfs check /dev/sdc --repair
> enabling repair mode
> Checking filesystem on /dev/sdc
> UUID: daa0dc6d-35b6-43ab-8333-894710a5b917
> checking extents
> checking fs roots
> checking root refs
> found 28672 bytes used err is 0
> total csum bytes: 0
> total tree bytes: 28672
> total fs tree bytes: 8192
> btree space waste bytes: 22420
> file data blocks allocated: 0
>   referenced 0
> Btrfs v0.20-rc1-238-g170881a-dirty
> ---------------------------------------------------------------
>
>
> I am not sure if I have a wipe -a working for btrfs,
> so I would clean using dd.
>
> # dd if=/dev/zero bs=1 count=8 of=/dev/sdb seek=$((64*1024+64))
> 8+0 records in
> 8+0 records out
> 8 bytes (8 B) copied, 0.000324503 s, 24.7 kB/s
>
> # dd if=/dev/zero bs=1 count=8 of=/dev/sdb seek=$((64*1024*1024+64))
> 8+0 records in
> 8+0 records out
> 8 bytes (8 B) copied, 0.000364635 s, 21.9 kB/s
>
> # dd if=/dev/zero bs=1 count=8 of=/dev/sdb seek=$((256*1024*1024*1024+64))
> dd: `/dev/sdb': cannot seek: Invalid argument
> 0+0 records in
> 0+0 records out
> 0 bytes (0 B) copied, 0.000430846 s, 0.0 kB/s
>
> This behavior is same before and after the patch.
>
> # btrfs check /dev/sdb
> No valid Btrfs found on /dev/sdb
> # btrfs check /dev/sdb -s 1
> using SB copy 1, bytenr 67108864
> No valid Btrfs found on /dev/sdb
> # btrfs check /dev/sdb -s 2
> using SB copy 2, bytenr 274877906944
> No valid Btrfs found on /dev/sdb
> #
> ------------------------
>
>   # mkfs.btrfs /dev/sdb /dev/sdc -f && mount /dev/sdc /btrfs
>
>   # dd if=/dev/zero bs=1 count=8 of=/dev/sdb seek=$((64*1024+64))
>   # dd if=/dev/zero bs=1 count=8 of=/dev/sdb seek=$((64*1024*1024+64))
>   # dd if=/dev/zero bs=1 count=8 of=/dev/sdb
> seek=$((256*1024*1024*1024+64))
>
> # mkfs.btrfs /dev/sdb
>
> WARNING! - Btrfs v0.20-rc1-238-g170881a-dirty IS EXPERIMENTAL
> WARNING! - see http://btrfs.wiki.kernel.org before using
>
> /dev/sdb is mounted
>
>
> # umount /btrfs
>
> # mkfs.btrfs /dev/sdb
>
> WARNING! - Btrfs v0.20-rc1-238-g170881a-dirty IS EXPERIMENTAL
> WARNING! - see http://btrfs.wiki.kernel.org before using
>
> /dev/sdb appears to contain an existing filesystem (btrfs).
> Use the -f option to force overwrite.
> #
>
> -------------------------
>
>
> # mkfs.btrfs /dev/sdd /dev/sde -f
>
> WARNING! - Btrfs v0.20-rc1-238-g170881a-dirty IS EXPERIMENTAL
> WARNING! - see http://btrfs.wiki.kernel.org before using
>
> adding device /dev/sde id 2
> fs created label (null) on /dev/sdd
>      nodesize 4096 leafsize 4096 sectorsize 4096 size 93.22GB
> Btrfs v0.20-rc1-238-g170881a-dirty
> # mount /dev/sde /btrfs
> # umount /btrfs
> # dd if=/dev/zero bs=1 count=8 of=/dev/sde seek=$((64*1024+64))
> 8+0 records in
> 8+0 records out
> 8 bytes (8 B) copied, 0.0149415 s, 0.5 kB/s
>
> remove /dev/sdd
>
> # x="0 0 3 0"
> # echo "scsi remove-single-device $x" > /proc/scsi/scsi
> # lsscsi
> [0:0:0:0]    disk    Sun      boot1            V1.0  /dev/sda
> [0:0:2:0]    disk    Sun      boot3            V1.0  /dev/sdc
> [0:0:4:0]    disk    Sun      boot5            V1.0  /dev/sde
> [0:1:0:0]    disk    SEAGATE  ST914602SSUN146G 0603  -
> [0:1:1:0]    disk    SEAGATE  ST914602SSUN146G 0603  -
> [0:3:0:0]    enclosu ADAPTEC  Virtual SGPIO  0 0001  -
>
>
> # btrfs check /dev/sde
> No valid Btrfs found on /dev/sde
>
> # btrfs check /dev/sde -s 1
> using SB copy 1, bytenr 67108864
> warning, device 1 is missing
> warning, device 1 is missing
> warning devid 1 not found already
> Checking filesystem on /dev/sde
> UUID: fa08122d-832f-4f32-87ee-58eb9380d5da
> checking extents
> checking fs roots
> checking root refs
> found 815104 bytes used err is 0
> total csum bytes: 0
> total tree bytes: 28672
> total fs tree bytes: 8192
> btree space waste bytes: 21476
> file data blocks allocated: 786432
>   referenced 786432
> Btrfs v0.20-rc1-238-g170881a-dirty
>
> # ./btrfs-select-super -s 1 /dev/sde
> using SB copy 1, bytenr 67108864
> ERROR: device scan failed '/dev/sdc' - Invalid argument
> warning, device 1 is missing
> warning, device 1 is missing
> warning devid 1 not found already
>
> # btrfs check /dev/sde
> warning, device 1 is missing
> warning, device 1 is missing
> warning devid 1 not found already
> Checking filesystem on /dev/sde
> UUID: fa08122d-832f-4f32-87ee-58eb9380d5da
> checking extents
> checking fs roots
> checking root refs
> found 815104 bytes used err is 0
> total csum bytes: 0
> total tree bytes: 28672
> total fs tree bytes: 8192
> btree space waste bytes: 21476
> file data blocks allocated: 786432
>   referenced 786432
> Btrfs v0.20-rc1-238-g170881a-dirty
> #
> ---------------
>
>
> Thanks, Anand
>
>
> On 03/12/2013 02:16 AM, David Sterba wrote:
>> On Mon, Mar 11, 2013 at 10:03:46AM -0500, Eric Sandeen wrote:
>>> IMHO, nothing should be checking the backup superblocks unless
>>> explicitly
>>> told to.
>>
>> That's the whole point I believe.
>>
>> update the infrastructure, every SB access looks to the first copy
>> unless told by command line options.
>>
>>
>> david
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
> --
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diff mbox

Patch

diff --git a/cmds-device.c b/cmds-device.c
index 1b8f378..9447e7f 100644
--- a/cmds-device.c
+++ b/cmds-device.c
@@ -203,7 +203,8 @@  static int cmd_scan_dev(int argc, char **argv)
 
 		printf("Scanning for Btrfs filesystems\n");
 		if(checklist)
-			ret = btrfs_scan_block_devices(BTRFS_SCAN_REGISTER);
+			ret = btrfs_scan_block_devices(BTRFS_SCAN_REGISTER|
+						       BTRFS_SCAN_BACKUP_SB);
 		else
 			ret = btrfs_scan_one_dir("/dev", BTRFS_SCAN_REGISTER);
 		if (ret){
diff --git a/cmds-filesystem.c b/cmds-filesystem.c
index 2210020..d2e708d 100644
--- a/cmds-filesystem.c
+++ b/cmds-filesystem.c
@@ -257,7 +257,7 @@  static int cmd_show(int argc, char **argv)
 		usage(cmd_show_usage);
 
 	if(checklist)
-		ret = btrfs_scan_block_devices(0);
+		ret = btrfs_scan_block_devices(BTRFS_SCAN_BACKUP_SB);
 	else
 		ret = btrfs_scan_one_dir("/dev", 0);
 
diff --git a/cmds-replace.c b/cmds-replace.c
index 4cc32df..f6e1619 100644
--- a/cmds-replace.c
+++ b/cmds-replace.c
@@ -275,7 +275,8 @@  static int cmd_start_replace(int argc, char **argv)
 		goto leave_with_error;
 	}
 	ret = btrfs_scan_one_device(fddstdev, dstdev, &fs_devices_mnt,
-				    &total_devs, BTRFS_SUPER_INFO_OFFSET);
+				    &total_devs, BTRFS_SUPER_INFO_OFFSET,
+				    BTRFS_SCAN_BACKUP_SB);
 	if (ret >= 0 && !force_using_targetdev) {
 		fprintf(stderr,
 			"Error, target device %s contains filesystem, use '-f' to force overwriting.\n",
diff --git a/disk-io.c b/disk-io.c
index 33e7e78..914b567 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -825,7 +825,8 @@  static struct btrfs_fs_info *__open_ctree_fd(int fp, const char *path,
 	posix_fadvise(fp, 0, 0, POSIX_FADV_DONTNEED);
 
 	ret = btrfs_scan_one_device(fp, path, &fs_devices,
-				    &total_devs, sb_bytenr);
+				    &total_devs, sb_bytenr,
+				    BTRFS_SCAN_BACKUP_SB);
 
 	if (ret) {
 		fprintf(stderr, "No valid Btrfs found on %s\n", path);
@@ -834,7 +835,7 @@  static struct btrfs_fs_info *__open_ctree_fd(int fp, const char *path,
 
 	if (total_devs != 1) {
 		ret = btrfs_scan_for_fsid(fs_devices, total_devs,
-			BTRFS_SCAN_REGISTER);
+			BTRFS_SCAN_REGISTER|BTRFS_SCAN_BACKUP_SB);
 		if (ret)
 			goto out;
 	}
@@ -1102,7 +1103,7 @@  struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr,
 }
 
 int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr,
-	u64 flags)
+			 u64 flags)
 {
 	u8 fsid[BTRFS_FSID_SIZE];
 	int fsid_is_initialized = 0;
diff --git a/find-root.c b/find-root.c
index c76de2b..40cacf1 100644
--- a/find-root.c
+++ b/find-root.c
@@ -102,7 +102,8 @@  static struct btrfs_root *open_ctree_broken(int fd, const char *device)
 	u64 features;
 
 	ret = btrfs_scan_one_device(fd, device, &fs_devices,
-				    &total_devs, BTRFS_SUPER_INFO_OFFSET);
+				    &total_devs, BTRFS_SUPER_INFO_OFFSET,
+				    BTRFS_SCAN_BACKUP_SB);
 
 	if (ret) {
 		fprintf(stderr, "No valid Btrfs found on %s\n", device);
@@ -111,7 +112,7 @@  static struct btrfs_root *open_ctree_broken(int fd, const char *device)
 
 	if (total_devs != 1) {
 		ret = btrfs_scan_for_fsid(fs_devices, total_devs,
-			BTRFS_SCAN_REGISTER);
+			BTRFS_SCAN_REGISTER|BTRFS_SCAN_BACKUP_SB);
 		if (ret)
 			goto out;
 	}
diff --git a/utils.c b/utils.c
index feee572..95dee29 100644
--- a/utils.c
+++ b/utils.c
@@ -835,7 +835,8 @@  int check_mounted_where(int fd, const char *file, char *where, int size,
 
 	/* scan the initial device */
 	ret = btrfs_scan_one_device(fd, file, &fs_devices_mnt,
-				    &total_devs, BTRFS_SUPER_INFO_OFFSET);
+				    &total_devs, BTRFS_SUPER_INFO_OFFSET,
+				    BTRFS_SCAN_BACKUP_SB);
 	is_btrfs = (ret >= 0);
 
 	/* scan other devices */
@@ -1032,7 +1033,8 @@  again:
 		}
 		ret = btrfs_scan_one_device(fd, fullpath, &tmp_devices,
 					    &num_devices,
-					    BTRFS_SUPER_INFO_OFFSET);
+					    BTRFS_SUPER_INFO_OFFSET,
+					    BTRFS_SCAN_BACKUP_SB);
 		if (ret == 0 && flags & BTRFS_SCAN_REGISTER) {
 			btrfs_register_one_device(fullpath);
 		}
@@ -1361,7 +1363,8 @@  scan_again:
 		}
 		ret = btrfs_scan_one_device(fd, fullpath, &tmp_devices,
 					    &num_devices,
-					    BTRFS_SUPER_INFO_OFFSET);
+					    BTRFS_SUPER_INFO_OFFSET,
+					    flags);
 		if (ret == 0 && flags & BTRFS_SCAN_REGISTER) {
 			btrfs_register_one_device(fullpath);
 		}
diff --git a/volumes.c b/volumes.c
index b6e3f29..e1795e3 100644
--- a/volumes.c
+++ b/volumes.c
@@ -212,7 +212,7 @@  fail:
 
 int btrfs_scan_one_device(int fd, const char *path,
 			  struct btrfs_fs_devices **fs_devices_ret,
-			  u64 *total_devs, u64 super_offset)
+			  u64 *total_devs, u64 super_offset, u64 flags)
 {
 	struct btrfs_super_block *disk_super;
 	char *buf;
@@ -227,7 +227,7 @@  int btrfs_scan_one_device(int fd, const char *path,
 	}
 	disk_super = (struct btrfs_super_block *)buf;
 	ret = btrfs_read_dev_super(fd, disk_super, super_offset,
-		BTRFS_SCAN_BACKUP_SB);
+				flags);
 	if (ret < 0) {
 		ret = -EIO;
 		goto error_brelse;
diff --git a/volumes.h b/volumes.h
index 911f788..f87aa5b 100644
--- a/volumes.h
+++ b/volumes.h
@@ -179,7 +179,7 @@  int btrfs_update_device(struct btrfs_trans_handle *trans,
 			struct btrfs_device *device);
 int btrfs_scan_one_device(int fd, const char *path,
 			  struct btrfs_fs_devices **fs_devices_ret,
-			  u64 *total_devs, u64 super_offset);
+			  u64 *total_devs, u64 super_offset, u64 flags);
 int btrfs_num_copies(struct btrfs_mapping_tree *map_tree, u64 logical, u64 len);
 int btrfs_bootstrap_super_map(struct btrfs_mapping_tree *map_tree,
 			      struct btrfs_fs_devices *fs_devices);