Btrfs-progs 4.1, released June 2015, includes support for changing the
UUID of a btrfs file system using the btrfstune command. Check for
availability by looking for the -u option in the btrfstune help output.
Use btrfstune like this:
# umount /dev/sdb1
# btrfstune -f -u /dev/sdb1
Current fsid: e7ad5dba-d721-4f99-990b-1ba2901c8ad2
New fsid: 231563d9-e173-410d-b1da-d34c4319a423
Set superblock flag CHANGING_FSID
Change fsid in extents
Change fsid on devices
Clear superblock flag CHANGING_FSID
Fsid change finished
# echo $?
0
Bug 751337 - btrfstune in btrfs-progs 4.1 supports changing the file
system UUID
Linux can only show a single device name in /proc/mounts and /etc/mtab
for each mounted btrfs, even if it is a multi-device file system. So
GParted only shows a mount point for one of the devices in the btrfs, no
matter how many devices are part of the file system.
# mkfs.btrfs /dev/sdb1 /dev/sdb2
# btrfs filesystem show /dev/sdb1
Label: none uuid: 36eb51a2-2927-4c92-820f-b2f0b5cdae50
Total devices 2 FS bytes used 156.00KB
devid 2 size 2.00GB used 512.00MB path /dev/sdb2
devid 1 size 2.00GB used 240.75MB path /dev/sdb1
# mount /dev/sdb1 /mnt/1
# grep btrfs /proc/mounts
/dev/sdb1 /mnt/1 btrfs rw,seclabel,relatime,ssd,space_cache 0 0
GParted only shows the mount point for /dev/sdb1 as /mnt/1, but nothing
for /dev/sdb2.
Make GParted report the same mount point for all devices included in a
multi-device btrfs file system.
Add btrfs specific get_mount_device() method to report the mounting
device, if any, for the btrfs file system in the occupying the device in
question. Uses the existing cache of btrfs file system device
membership. Also extract common code from GParted_Core::
set_mountpoints() into set_mountpoints_helper().
Bug #723842 - GParted resizes the wrong filesystem (does not pass the
devid to btrfs filesystem resize)
Busy detection of file systems works by checking if the device is
mounted (appears in the mount_info map). For a multi-device btrfs file
system this will only report one of the devices as busy, not all of
them.
# btrfs filesystem show /dev/sdb1
Label: none uuid: 36eb51a2-2927-4c92-820f-b2f0b5cdae50
Total devices 2 FS bytes used 156.00KB
devid 2 size 2.00GB used 512.00MB path /dev/sdb2
devid 1 size 2.00GB used 240.75MB path /dev/sdb1
# mount /dev/sdb1 /mnt/1
# grep btrfs /proc/mounts
/dev/sdb1 /mnt/1 btrfs rw,seclabel,relatime,ssd,space_cache 0 0
GParted will only report /dev/sdb1 as busy, but not /dev/sdb2.
Add btrfs specific is_busy() method which reports the device as busy if
any of the devices in the btrfs file system are mounted. This uses a
cache which maps device membership in all btrfs file systems. The cache
is cleared on GParted refresh and incrementally populated as each btrfs
partition is checked for busy status.
WARNING:
Removal of the mounting device from a btrfs file system makes it
impossible to determine whether the file system is mounted or not for
linux <= 3.4. This is because /proc/mounts continues to show the old
device which is no longer a member of the file system.
# btrfs device delete /dev/sdb1 /mnt/1
# sync
# grep btrfs /proc/mounts
/dev/sdb1 /mnt/1 btrfs rw,seclabel,relatime,ssd,space_cache 0 0
# btrfs filesystem show /dev/sdb1
# btrfs filesystem show /dev/sdb2
Label: none uuid: 36eb51a2-2927-4c92-820f-b2f0b5cdae50
Total devices 1 FS bytes used 28.00KB
devid 2 size 2.00GB used 1.02GB path /dev/sdb2
Fixed in linux 3.5 by commit:
Btrfs: implement ->show_devname
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=9c5085c147989d48dfe74194b48affc23f376650
Bug #723842 - GParted resizes the wrong filesystem (does not pass the
devid to btrfs filesystem resize)
This is part of parent bug:
Bug #721455 - Obsolete info in license text on multiple modules
and GNOME Goal:
https://wiki.gnome.org/Initiatives/GnomeGoals/Proposals
* verify all source files to make sure they have a license and a
copyright, and that both are up-to-date
Bug #721565 - License text contains obsolete FSF postal address
Include guards need to be unique within GParted code and all included
library header files.
http://en.wikipedia.org/wiki/Include_guard#Difficulties
Use this model for all include guards:
#ifndef GPARTED_FILE_NAME_H
#define GPARTED_FILE_NAME_H
...
#endif /* GPARTED_FILE_NAME_H */
Closes Bug #539297 - Make include guards unique
Many filesystems do not implement some of their methods, but had to provide
dummy implementations. Remove all of the dummy implementations and instead
just provide one in the base FileSystem class.
This commit only adds a remove() method to every file system and an
optional call to it in the relevant operations. All remove() methods
are no operations and not enabled.
The remove() method provides explicit controlled removal of a file
system before the partition is deleted or overwritten by being formatted
or pasted into. When implemented, it appears as an extra step in the
relevant operation. The file system specific remove() method is
explicitly allowed to fail and stop the operations currently being
applied.
This is different to the existing erase_filesystem_signatures() which
wipes any previous file system signatures immediately before a new file
system is written to ensure there is no possibility of the partition
containing two or more different file system signatures. It never fails
or reports anything to the user.
NOTE:
Most file systems should NOT implement a remove() method as it will
prevent recovery from accidental partition deletion.
Bug #670171 - Add LVM PV read-write support
The member functions btrfs_size_to_num(), btrfs_size_max_delta() and
btrfs_size_to_gdouble() don't access any member variables. Therefore
they don't need the const qualifier allowing them to be called when the
btrfs object is const for read-only access to member variables, but
instead need to be static member functions with no access to member
variables.
The btrfs programs only provide approximations of file system sizes
because they display figures using binary prefix multipliers to two
decimal places of precision. E.g. 2.00GB. For partition sizes where
the contained file system size rounds upwards, GParted will fail to read
the file system usage and report a warning because the file system will
appear to be larger than the partition.
For example, create a 2047 MiB partition containing a btrfs file system
and display its size.
# btrfs filesystem show
Label: none uuid: 92535375-5e76-4a70-896a-8d796a577993
Total devices 1 FS bytes used 28.00KB
devid 1 size 2.00GB used 240.62MB path /dev/sda12
The file system size appears to be 2048 MiB, but that is larger than the
partition, hence the issue GParted has. (Actually uses the btrfs devid
size which is the size of the btrfs file system within the partition in
question).
This issue is new with the fix for Bug #499202 because it queries the
file system sizes for the first time. The same issue could
theoretically occur previously, but with the used figure (FS bytes
used). This would have been virtually impossible to trigger because
btrfs file system would have to have been greater than 99% full, but
btrfs has been notorious for early reporting of file system full.
The fix is that if a btrfs file system size appears larger than the
partition size, but the minimum possible size which could have been
rounded to the reported figure is within the partition size use the
smaller partition size instead. Apply the method to the used figure
too, in case the file system is 100% full. Also if the btrfs file
system size appears smaller than the partition size, but the maximum
possible size which could have been rounded to the reported figure is
within the partition size use the larger partition size instead to avoid
reporting, presumably false, unallocated space. Not applied to file
system used figure.
Bug 499202 - gparted does not see the difference if partition size
differs from filesystem size
Update file system specific implementations to set the size and free
space, thus allowing the unallocated space in the partition to be
calculated, for the following unmounted file systems:
btrfs, ext2, ext3, ext4, fat16, fat32, jfs, nilfs2, ntfs, reiserfs,
reiser4, xfs
Bug #499202 - gparted does not see the difference if partition size
differs from filesystem size
Add the ability to set a new random UUID on file systems that provide
the appropriate tools to perform this action.
Update the help manual to include this new functionality. Also add
reference links to "setting a partition label" and "changing a
partition UUID" in the "copying and pasting a partition" section.
This patch does not include setting the UUID on an NTFS file system.
Bug #667278 - Add support for setting UUID
Bug #608308 - fix documentation - Copying and Pasting a Partition
This adds initial handlers for Btrfs; only .create, .check and
.read_label are done for now, via external btrfs-tools.
Other methods are still only stubs.
Mike Fleetwood