Comments (15)
shundhammer
commented on May 13, 2024
One approach would be to check if the current filesystem is Btrfs and list its subvolumes, but the Btrfs developers in their infinite wisdom decided that btrfs subvolume list <path> is a privileged operation, so QDirStat would have to use sudo with it and prompt for the root password (at which point I as a user would terminate the program and not use it any more).
This is broken by design. (but then, so are many things about Btrfs).
A simple info command like that should not require root privileges.
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shundhammer
commented on May 13, 2024
The stat shell command shows that a Btrfs subvolume has a different major/minor device ID than its parent filesystem.
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shundhammer
commented on May 13, 2024
Question to the world:
How do I find out without root privileges what subvolumes a Btrfs filesystem has?
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shundhammer
commented on May 13, 2024
It looks like a Btrfs subvolume always has i-node ID 256:
http://stackoverflow.com/questions/25908149/how-to-test-if-location-is-a-btrfs-subvolume
Tested on a sample Btrfs. Need to verify that this is reliable - and preferably documented.
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shundhammer
commented on May 13, 2024
The content of /proc/mounts can at least identify filesystems as Btrfs. The problem is just that even the toplevel mount point shows up as a mere subvolume there (which technically it is, but that's pretty irrelevant for the normal use case):
grep -i subvol /proc/mounts | column -t
/dev/vda6 / btrfs rw,relatime,space_cache,subvolid=259,subvol=/@/.snapshots/1/snapshot 0 0
/dev/vda6 /.snapshots btrfs rw,relatime,space_cache,subvolid=258,subvol=/@/.snapshots 0 0
/dev/vda6 /var/lib/named btrfs rw,relatime,space_cache,subvolid=273,subvol=/@/var/lib/named 0 0
/dev/vda6 /srv btrfs rw,relatime,space_cache,subvolid=263,subvol=/@/srv 0 0
/dev/vda6 /var/lib/libvirt/images btrfs rw,relatime,space_cache,subvolid=268,subvol=/@/var/lib/libvirt/images 0 0
/dev/vda6 /opt btrfs rw,relatime,space_cache,subvolid=262,subvol=/@/opt 0 0
/dev/vda6 /var/opt btrfs rw,relatime,space_cache,subvolid=276,subvol=/@/var/opt 0 0
/dev/vda6 /usr/local btrfs rw,relatime,space_cache,subvolid=265,subvol=/@/usr/local 0 0
/dev/vda6 /var/lib/mailman btrfs rw,relatime,space_cache,subvolid=270,subvol=/@/var/lib/mailman 0 0
/dev/vda6 /var/lib/mariadb btrfs rw,relatime,space_cache,subvolid=271,subvol=/@/var/lib/mariadb 0 0
/dev/vda6 /var/crash btrfs rw,relatime,space_cache,subvolid=267,subvol=/@/var/crash 0 0
/dev/vda6 /boot/grub2/x86_64-efi btrfs rw,relatime,space_cache,subvolid=261,subvol=/@/boot/grub2/x86_64-efi 0 0
/dev/vda6 /boot/grub2/i386-pc btrfs rw,relatime,space_cache,subvolid=260,subvol=/@/boot/grub2/i386-pc 0 0
/dev/vda6 /var/lib/mysql btrfs rw,relatime,space_cache,subvolid=272,subvol=/@/var/lib/mysql 0 0
/dev/vda6 /var/lib/pgsql btrfs rw,relatime,space_cache,subvolid=274,subvol=/@/var/lib/pgsql 0 0
/dev/vda6 /var/log btrfs rw,relatime,space_cache,subvolid=275,subvol=/@/var/log 0 0
/dev/vda6 /var/tmp btrfs rw,relatime,space_cache,subvolid=278,subvol=/@/var/tmp 0 0
/dev/vda6 /var/spool btrfs rw,relatime,space_cache,subvolid=277,subvol=/@/var/spool 0 0
/dev/vda6 /tmp btrfs rw,relatime,space_cache,subvolid=264,subvol=/@/tmp 0 0
/dev/vda6 /var/lib/machines btrfs rw,relatime,space_cache,subvolid=269,subvol=/@/var/lib/machines 0 0
/dev/vda6 /var/cache btrfs rw,relatime,space_cache,subvolid=266,subvol=/@/var/cache 0 0
Now the question is how to tell the difference between a subvolume mount point and the mount point of a full-fledged Btrfs into another Btrfs: /home on a separate partition might be a Btrfs as well, so we couldn't tell the difference between /home and any subvolume of /.
This output shows /dev/vda6 as the device for all of those Btrfs subvolumes, but the output of the stat() syscall or the stat shell command shows another major/minor device ID for each of the subvolumes.
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shundhammer
commented on May 13, 2024
Once I know that I am on one of those Btrfs partitions, I can do string comparisons: Am I still on /dev/vda6, or is another (Btrfs?) partition mounted there, too (say, /dev/vda7)? But how do I find out in the beginning that I am on /dev/vda6? The minor/major device ID returned from lstat() is not the one from /dev/vda6, but from some Btrfs device that does not show up below /dev (or does it? I couldn't find it).
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shundhammer
commented on May 13, 2024
Btrfs:
e76:~ # df /
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/vda6 40434688 3407732 36598220 9% /
e76:~ # stat /
File: '/'
Size: 156 Blocks: 0 IO Block: 4096 directory
Device: 26h/38d Inode: 256 Links: 1
Access: (0755/drwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2016-12-06 11:43:00.000000000 +0100
Modify: 2016-12-06 11:40:46.700000000 +0100
Change: 2016-12-06 11:40:46.700000000 +0100
Birth: -
e76:~ # ls -l /dev/vda6
brw-rw---- 1 root disk 253, 6 Dec 6 11:45 /dev/vda6
I.e. stat() returns major/minor device 0x0026, but the underlying partition /dev/vda6 has major/minor device 0xFD06.
XFS:
morgul:~ # df /
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda3 41924608 23577132 18347476 57% /
morgul:~ # stat /
File: '/'
Size: 4096 Blocks: 8 IO Block: 4096 directory
Device: 803h/2051d Inode: 96 Links: 36
Access: (0755/drwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2016-12-06 12:25:23.564113162 +0100
Modify: 2016-11-30 16:47:40.127400702 +0100
Change: 2016-11-30 16:47:40.127400702 +0100
Birth: -
morgul:~ # ls -l /dev/sda3
brw-rw---- 1 root disk 8, 3 Nov 30 16:47 /dev/sda3
stat() returns 0x0803, and this is the underlying partition's (/dev/sda3) major/minor device ID.
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shundhammer
commented on May 13, 2024
See also
https://bugzilla.suse.com/show_bug.cgi?id=996479
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shundhammer
commented on May 13, 2024
There is some more (but not much more) information in /proc/self/mountinfo:
e76:~ # grep btrfs /proc/self/mountinfo | column -t
59 0 0:34 /@/.snapshots/1/snapshot / rw,relatime shared:1 - btrfs /dev/vda6 rw,space_cache,subvolid=259,subvol=/@/.snapshots/1/snapshot
79 59 0:34 /@/.snapshots /.snapshots rw,relatime shared:26 - btrfs /dev/vda6 rw,space_cache,subvolid=258,subvol=/@/.snapshots
69 59 0:34 /@/var/lib/named /var/lib/named rw,relatime shared:27 - btrfs /dev/vda6 rw,space_cache,subvolid=273,subvol=/@/var/lib/named
71 59 0:34 /@/srv /srv rw,relatime shared:28 - btrfs /dev/vda6 rw,space_cache,subvolid=263,subvol=/@/srv
73 59 0:34 /@/var/lib/libvirt/images /var/lib/libvirt/images rw,relatime shared:29 - btrfs /dev/vda6 rw,space_cache,subvolid=268,subvol=/@/var/lib/libvirt/images
75 59 0:34 /@/opt /opt rw,relatime shared:30 - btrfs /dev/vda6 rw,space_cache,subvolid=262,subvol=/@/opt
77 59 0:34 /@/var/opt /var/opt rw,relatime shared:31 - btrfs /dev/vda6 rw,space_cache,subvolid=276,subvol=/@/var/opt
91 59 0:34 /@/usr/local /usr/local rw,relatime shared:32 - btrfs /dev/vda6 rw,space_cache,subvolid=265,subvol=/@/usr/local
81 59 0:34 /@/var/lib/mailman /var/lib/mailman rw,relatime shared:33 - btrfs /dev/vda6 rw,space_cache,subvolid=270,subvol=/@/var/lib/mailman
83 59 0:34 /@/var/lib/mariadb /var/lib/mariadb rw,relatime shared:34 - btrfs /dev/vda6 rw,space_cache,subvolid=271,subvol=/@/var/lib/mariadb
85 59 0:34 /@/var/crash /var/crash rw,relatime shared:35 - btrfs /dev/vda6 rw,space_cache,subvolid=267,subvol=/@/var/crash
87 59 0:34 /@/boot/grub2/x86_64-efi /boot/grub2/x86_64-efi rw,relatime shared:36 - btrfs /dev/vda6 rw,space_cache,subvolid=261,subvol=/@/boot/grub2/x86_64-efi
89 59 0:34 /@/boot/grub2/i386-pc /boot/grub2/i386-pc rw,relatime shared:37 - btrfs /dev/vda6 rw,space_cache,subvolid=260,subvol=/@/boot/grub2/i386-pc
80 59 0:34 /@/var/lib/mysql /var/lib/mysql rw,relatime shared:38 - btrfs /dev/vda6 rw,space_cache,subvolid=272,subvol=/@/var/lib/mysql
95 59 0:34 /@/var/lib/pgsql /var/lib/pgsql rw,relatime shared:39 - btrfs /dev/vda6 rw,space_cache,subvolid=274,subvol=/@/var/lib/pgsql
97 59 0:34 /@/var/log /var/log rw,relatime shared:40 - btrfs /dev/vda6 rw,space_cache,subvolid=275,subvol=/@/var/log
99 59 0:34 /@/var/tmp /var/tmp rw,relatime shared:41 - btrfs /dev/vda6 rw,space_cache,subvolid=278,subvol=/@/var/tmp
101 59 0:34 /@/var/spool /var/spool rw,relatime shared:42 - btrfs /dev/vda6 rw,space_cache,subvolid=277,subvol=/@/var/spool
103 59 0:34 /@/tmp /tmp rw,relatime shared:43 - btrfs /dev/vda6 rw,space_cache,subvolid=264,subvol=/@/tmp
105 59 0:34 /@/var/lib/machines /var/lib/machines rw,relatime shared:44 - btrfs /dev/vda6 rw,space_cache,subvolid=269,subvol=/@/var/lib/machines
107 59 0:34 /@/var/cache /var/cache rw,relatime shared:45 - btrfs /dev/vda6 rw,space_cache,subvolid=266,subvol=/@/var/cache
e76:~ # l /dev/vda6
brw-rw---- 1 root disk 253, 6 Dec 6 11:45 /dev/vda6
See also https://www.kernel.org/doc/Documentation/filesystems/proc.txt :
3.5 /proc/self/mountinfo - Information about mounts
This file contains lines of the form:
36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
(1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11)(1) mount ID: unique identifier of the mount (may be reused after umount)
(2) parent ID: ID of parent (or of self for the top of the mount tree)
(3) major:minor: value of st_dev for files on filesystem
(4) root: root of the mount within the filesystem
(5) mount point: mount point relative to the process's root
(6) mount options: per mount options
(7) optional fields: zero or more fields of the form "tag[:value]"
(8) separator: marks the end of the optional fields
(9) filesystem type: name of filesystem of the form "type[.subtype]"
(10) mount source: filesystem specific information or "none"
(11) super options: per super block optionsParsers should ignore all unrecognised optional fields. Currently the
possible optional fields are:shared:X mount is shared in peer group X
master:X mount is slave to peer group X
propagate_from:X mount is slave and receives propagation from peer group X (*)
unbindable mount is unbindable
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shundhammer
commented on May 13, 2024
Now working on a promising approach in branch huha-subvols:
Reading and storing /proc/mounts (or fallback /etc/mtab) and comparing the device names when a mount point is found.
The initial mount point of QDirStat's tree is found by canonicalizing the path (removing symlinks and and ".." parts) and comparing that path to any of the known mount points from /proc/mounts. If there is no corresponding mount point, the last path component is removed for the next lookup etc. up to /.
If no device name can be obtained for either the tree root or for a mount point that was found, the simple major/minor device number comparison has priority, i.e. it is considered a filesystem boundary when they are different. That's what QDirStat (and KDirStat) always did.
But for Btrfs, even though major/minor are different when a subvolume mount point is detected, if the device name is still the same (both directories on, say, /dev/sda2), it is considered the same filesystem, and QDirStat keeps reading.
A nice side effect is that this is not limited to Btrfs: Other filesystem types that have a similar behaviour will benefit from that, too.
Right now the toplevel .snapshots directory is still excluded, but that is by sheer accident: There is a very old exclude rule for that name because some backup tools use it, too.
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shundhammer
commented on May 13, 2024
Tested on an openSUSE Tumbleweed VM with a root Btrfs and a /home Btrfs, and it appears to work great: When started to read /, it doesn't stop at all the subvolumes on that filesystem, but it does stop at all the other mount points, including /home (which is also a Btrfs, so this might have been problematic).
From the log:
shundhammer@d165:/tmp> egrep -i "(device|mount point)" qdirstat-1000.log
2016-12-08 11:03:54.988 [3027] <Info> DirTree.cpp:98 startReading(): device: /dev/vda2
2016-12-08 11:03:54.999 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /.snapshots is still on the same device /dev/vda2
2016-12-08 11:03:54.999 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /opt is still on the same device /dev/vda2
2016-12-08 11:03:54.999 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /srv is still on the same device /dev/vda2
2016-12-08 11:03:54.999 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /tmp is still on the same device /dev/vda2
2016-12-08 11:03:54.999 [3027] <Debug> DirReadJob.cpp:199 startReading(): Found mount point /home
2016-12-08 11:03:54.999 [3027] <Debug> DirReadJob.cpp:199 startReading(): Found mount point /dev
2016-12-08 11:03:54.999 [3027] <Debug> DirReadJob.cpp:199 startReading(): Found mount point /proc
2016-12-08 11:03:54.999 [3027] <Debug> DirReadJob.cpp:199 startReading(): Found mount point /sys
2016-12-08 11:03:54.999 [3027] <Debug> DirReadJob.cpp:199 startReading(): Found mount point /run
2016-12-08 11:03:55.067 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /usr/local is still on the same device /dev/vda2
2016-12-08 11:03:55.067 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/cache is still on the same device /dev/vda2
2016-12-08 11:03:55.067 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/crash is still on the same device /dev/vda2
2016-12-08 11:03:55.067 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/log is still on the same device /dev/vda2
2016-12-08 11:03:55.067 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/opt is still on the same device /dev/vda2
2016-12-08 11:03:55.067 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/spool is still on the same device /dev/vda2
2016-12-08 11:03:55.067 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/tmp is still on the same device /dev/vda2
2016-12-08 11:03:55.077 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /boot/grub2/i386-pc is still on the same device /dev/vda2
2016-12-08 11:03:55.077 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /boot/grub2/x86_64-efi is still on the same device /dev/vda2
2016-12-08 11:03:55.100 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/lib/machines is still on the same device /dev/vda2
2016-12-08 11:03:55.100 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/lib/mailman is still on the same device /dev/vda2
2016-12-08 11:03:55.100 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/lib/mariadb is still on the same device /dev/vda2
2016-12-08 11:03:55.100 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/lib/mysql is still on the same device /dev/vda2
2016-12-08 11:03:55.100 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/lib/named is still on the same device /dev/vda2
2016-12-08 11:03:55.100 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/lib/pgsql is still on the same device /dev/vda2
2016-12-08 11:03:55.178 [3027] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/lib/libvirt/images is still on the same device /dev/vda2
Subvolumes on both Btrfs partitions:
shundhammer@d165:/tmp> sudo btrfs subvolume list /
ID 257 gen 32 top level 5 path @
ID 258 gen 524 top level 257 path @/.snapshots
ID 259 gen 533 top level 258 path @/.snapshots/1/snapshot
ID 260 gen 529 top level 257 path @/boot/grub2/i386-pc
ID 261 gen 529 top level 257 path @/boot/grub2/x86_64-efi
ID 262 gen 529 top level 257 path @/opt
ID 263 gen 529 top level 257 path @/srv
ID 264 gen 533 top level 257 path @/tmp
ID 265 gen 529 top level 257 path @/usr/local
ID 266 gen 533 top level 257 path @/var/cache
ID 267 gen 529 top level 257 path @/var/crash
ID 268 gen 529 top level 257 path @/var/lib/libvirt/images
ID 269 gen 34 top level 257 path @/var/lib/machines
ID 270 gen 529 top level 257 path @/var/lib/mailman
ID 271 gen 529 top level 257 path @/var/lib/mariadb
ID 272 gen 529 top level 257 path @/var/lib/mysql
ID 273 gen 529 top level 257 path @/var/lib/named
ID 274 gen 529 top level 257 path @/var/lib/pgsql
ID 275 gen 533 top level 257 path @/var/log
ID 276 gen 529 top level 257 path @/var/opt
ID 277 gen 533 top level 257 path @/var/spool
ID 278 gen 533 top level 257 path @/var/tmp
ID 283 gen 523 top level 258 path @/.snapshots/2/snapshot
shundhammer@d165:/tmp> sudo btrfs subvolume list /home
ID 257 gen 16 top level 5 path @
df output for a (reasonably) good overview of all the mount points:
shundhammer@d165:/tmp> df
Filesystem 1K-blocks Used Available Use% Mounted on
devtmpfs 1010564 0 1010564 0% /dev
tmpfs 1024132 108 1024024 1% /dev/shm
tmpfs 1024132 1372 1022760 1% /run
tmpfs 1024132 0 1024132 0% /sys/fs/cgroup
/dev/vda2 16346112 3448028 11090660 24% /
/dev/vda2 16346112 3448028 11090660 24% /var/log
/dev/vda2 16346112 3448028 11090660 24% /boot/grub2/i386-pc
/dev/vda2 16346112 3448028 11090660 24% /var/lib/named
/dev/vda2 16346112 3448028 11090660 24% /var/lib/mailman
/dev/vda2 16346112 3448028 11090660 24% /opt
/dev/vda2 16346112 3448028 11090660 24% /var/opt
/dev/vda2 16346112 3448028 11090660 24% /boot/grub2/x86_64-efi
/dev/vda2 16346112 3448028 11090660 24% /srv
/dev/vda2 16346112 3448028 11090660 24% /.snapshots
/dev/vda2 16346112 3448028 11090660 24% /var/lib/mysql
/dev/vda2 16346112 3448028 11090660 24% /var/crash
/dev/vda2 16346112 3448028 11090660 24% /var/lib/pgsql
/dev/vda2 16346112 3448028 11090660 24% /var/lib/mariadb
/dev/vda2 16346112 3448028 11090660 24% /var/lib/machines
/dev/vda2 16346112 3448028 11090660 24% /tmp
/dev/vda2 16346112 3448028 11090660 24% /var/lib/libvirt/images
/dev/vda2 16346112 3448028 11090660 24% /var/spool
/dev/vda2 16346112 3448028 11090660 24% /usr/local
/dev/vda2 16346112 3448028 11090660 24% /var/tmp
/dev/vda2 16346112 3448028 11090660 24% /var/cache
/dev/vda3 23492608 17328 21377520 1% /home
tmpfs 204828 16 204812 1% /run/user/1000
Finally, all the mount points:
shundhammer@d165:/tmp> mount | column -t
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
devtmpfs on /dev type devtmpfs (rw,nosuid,size=1010564k,nr_inodes=252641,mode=755)
securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)
tmpfs on /run type tmpfs (rw,nosuid,nodev,mode=755)
tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,mode=755)
cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd)
pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime)
cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices)
cgroup on /sys/fs/cgroup/net_cls,net_prio type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls,net_prio)
cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpu,cpuacct)
cgroup on /sys/fs/cgroup/pids type cgroup (rw,nosuid,nodev,noexec,relatime,pids)
cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio)
cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset)
cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer)
cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec,relatime,hugetlb)
cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event)
cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory)
/dev/vda2 on / type btrfs (rw,relatime,space_cache,subvolid=259,subvol=/@/.snapshots/1/snapshot)
systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=22,pgrp=1,timeout=0,minproto=5,maxproto=5,direct,pipe_ino=13138)
hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime)
mqueue on /dev/mqueue type mqueue (rw,relatime)
debugfs on /sys/kernel/debug type debugfs (rw,relatime)
/dev/vda2 on /var/log type btrfs (rw,relatime,space_cache,subvolid=275,subvol=/@/var/log)
/dev/vda2 on /boot/grub2/i386-pc type btrfs (rw,relatime,space_cache,subvolid=260,subvol=/@/boot/grub2/i386-pc)
/dev/vda2 on /var/lib/named type btrfs (rw,relatime,space_cache,subvolid=273,subvol=/@/var/lib/named)
/dev/vda2 on /var/lib/mailman type btrfs (rw,relatime,space_cache,subvolid=270,subvol=/@/var/lib/mailman)
/dev/vda2 on /opt type btrfs (rw,relatime,space_cache,subvolid=262,subvol=/@/opt)
/dev/vda2 on /var/opt type btrfs (rw,relatime,space_cache,subvolid=276,subvol=/@/var/opt)
/dev/vda2 on /boot/grub2/x86_64-efi type btrfs (rw,relatime,space_cache,subvolid=261,subvol=/@/boot/grub2/x86_64-efi)
/dev/vda2 on /srv type btrfs (rw,relatime,space_cache,subvolid=263,subvol=/@/srv)
/dev/vda2 on /.snapshots type btrfs (rw,relatime,space_cache,subvolid=258,subvol=/@/.snapshots)
/dev/vda2 on /var/lib/mysql type btrfs (rw,relatime,space_cache,subvolid=272,subvol=/@/var/lib/mysql)
/dev/vda2 on /var/crash type btrfs (rw,relatime,space_cache,subvolid=267,subvol=/@/var/crash)
/dev/vda2 on /var/lib/pgsql type btrfs (rw,relatime,space_cache,subvolid=274,subvol=/@/var/lib/pgsql)
/dev/vda2 on /var/lib/mariadb type btrfs (rw,relatime,space_cache,subvolid=271,subvol=/@/var/lib/mariadb)
/dev/vda2 on /var/lib/machines type btrfs (rw,relatime,space_cache,subvolid=269,subvol=/@/var/lib/machines)
/dev/vda2 on /tmp type btrfs (rw,relatime,space_cache,subvolid=264,subvol=/@/tmp)
/dev/vda2 on /var/lib/libvirt/images type btrfs (rw,relatime,space_cache,subvolid=268,subvol=/@/var/lib/libvirt/images)
/dev/vda2 on /var/spool type btrfs (rw,relatime,space_cache,subvolid=277,subvol=/@/var/spool)
/dev/vda2 on /usr/local type btrfs (rw,relatime,space_cache,subvolid=265,subvol=/@/usr/local)
/dev/vda2 on /var/tmp type btrfs (rw,relatime,space_cache,subvolid=278,subvol=/@/var/tmp)
/dev/vda2 on /var/cache type btrfs (rw,relatime,space_cache,subvolid=266,subvol=/@/var/cache)
/dev/vda3 on /home type btrfs (rw,relatime,space_cache,subvolid=257,subvol=/@)
tmpfs on /run/user/1000 type tmpfs (rw,nosuid,nodev,relatime,size=204828k,mode=700,uid=1000,gid=100)
fusectl on /sys/fs/fuse/connections type fusectl (rw,relatime)
gvfsd-fuse on /run/user/1000/gvfs type fuse.gvfsd-fuse (rw,nosuid,nodev,relatime,user_id=1000,group_id=100)
tracefs on /sys/kernel/debug/tracing type tracefs (rw,relatime)
from qdirstat.
shundhammer
commented on May 13, 2024
This concludes the C++ part of this issue. The Perl part in qdirstat-cache-writer still remains to be done; it's equally important there.
from qdirstat.
shundhammer
commented on May 13, 2024
Also tested successfully on a setup with Btrfs on LVM:
shundhammer@g138:/tmp> egrep -i "(device|mount point)" qdirstat-0.log
2016-12-08 13:33:01.889 [27685] <Info> DirTree.cpp:98 startReading(): device: /dev/mapper/system-root
2016-12-08 13:33:01.905 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /.snapshots is still on the same device /dev/mapper/system-root
2016-12-08 13:33:01.905 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /opt is still on the same device /dev/mapper/system-root
2016-12-08 13:33:01.905 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /srv is still on the same device /dev/mapper/system-root
2016-12-08 13:33:01.905 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /tmp is still on the same device /dev/mapper/system-root
2016-12-08 13:33:01.905 [27685] <Debug> DirReadJob.cpp:199 startReading(): Found mount point /home
2016-12-08 13:33:01.905 [27685] <Debug> DirReadJob.cpp:199 startReading(): Found mount point /dev
2016-12-08 13:33:01.905 [27685] <Debug> DirReadJob.cpp:199 startReading(): Found mount point /proc
2016-12-08 13:33:01.905 [27685] <Debug> DirReadJob.cpp:199 startReading(): Found mount point /sys
2016-12-08 13:33:01.905 [27685] <Debug> DirReadJob.cpp:199 startReading(): Found mount point /run
2016-12-08 13:33:01.987 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /usr/local is still on the same device /dev/mapper/system-root
2016-12-08 13:33:01.988 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/cache is still on the same device /dev/mapper/system-root
2016-12-08 13:33:01.988 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/crash is still on the same device /dev/mapper/system-root
2016-12-08 13:33:01.988 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/log is still on the same device /dev/mapper/system-root
2016-12-08 13:33:01.988 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/opt is still on the same device /dev/mapper/system-root
2016-12-08 13:33:01.988 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/spool is still on the same device /dev/mapper/system-root
2016-12-08 13:33:01.988 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/tmp is still on the same device /dev/mapper/system-root
2016-12-08 13:33:01.996 [27685] <Debug> DirReadJob.cpp:199 startReading(): Found mount point /.snapshots/1/snapshot
2016-12-08 13:33:01.996 [27685] <Debug> DirReadJob.cpp:199 startReading(): Found mount point /.snapshots/2/snapshot
2016-12-08 13:33:01.996 [27685] <Debug> DirReadJob.cpp:199 startReading(): Found mount point /.snapshots/3/snapshot
2016-12-08 13:33:01.996 [27685] <Debug> DirReadJob.cpp:199 startReading(): Found mount point /.snapshots/4/snapshot
2016-12-08 13:33:01.996 [27685] <Debug> DirReadJob.cpp:199 startReading(): Found mount point /.snapshots/5/snapshot
2016-12-08 13:33:01.997 [27685] <Debug> DirReadJob.cpp:199 startReading(): Found mount point /.snapshots/6/snapshot
2016-12-08 13:33:01.997 [27685] <Debug> DirReadJob.cpp:199 startReading(): Found mount point /.snapshots/7/snapshot
2016-12-08 13:33:01.997 [27685] <Debug> DirReadJob.cpp:199 startReading(): Found mount point /.snapshots/8/snapshot
2016-12-08 13:33:01.997 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /boot/grub2/i386-pc is still on the same device /dev/mapper/system-root
2016-12-08 13:33:01.997 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /boot/grub2/x86_64-efi is still on the same device /dev/mapper/system-root
2016-12-08 13:33:02.017 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/lib/machines is still on the same device /dev/mapper/system-root
2016-12-08 13:33:02.017 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/lib/mailman is still on the same device /dev/mapper/system-root
2016-12-08 13:33:02.017 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/lib/mariadb is still on the same device /dev/mapper/system-root
2016-12-08 13:33:02.017 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/lib/mysql is still on the same device /dev/mapper/system-root
2016-12-08 13:33:02.017 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/lib/named is still on the same device /dev/mapper/system-root
2016-12-08 13:33:02.017 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/lib/pgsql is still on the same device /dev/mapper/system-root
2016-12-08 13:33:02.070 [27685] <Info> DirReadJob.cpp:111 crossingFileSystems(): Mount point /var/lib/libvirt/images is still on the same device /dev/mapper/system-root
df output:
shundhammer@g138:/tmp> df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 986M 0 986M 0% /dev
tmpfs 1001M 100K 1001M 1% /dev/shm
tmpfs 1001M 1.4M 999M 1% /run
tmpfs 1001M 0 1001M 0% /sys/fs/cgroup
/dev/mapper/system-root 16G 3.6G 12G 25% /
/dev/mapper/system-root 16G 3.6G 12G 25% /var/opt
/dev/mapper/system-root 16G 3.6G 12G 25% /var/lib/named
/dev/mapper/system-root 16G 3.6G 12G 25% /var/cache
/dev/mapper/system-root 16G 3.6G 12G 25% /var/lib/machines
/dev/mapper/system-root 16G 3.6G 12G 25% /usr/local
/dev/mapper/system-root 16G 3.6G 12G 25% /boot/grub2/i386-pc
/dev/mapper/system-root 16G 3.6G 12G 25% /var/crash
/dev/mapper/system-root 16G 3.6G 12G 25% /var/lib/mariadb
/dev/mapper/system-root 16G 3.6G 12G 25% /boot/grub2/x86_64-efi
/dev/mapper/system-root 16G 3.6G 12G 25% /var/lib/pgsql
/dev/mapper/system-root 16G 3.6G 12G 25% /var/spool
/dev/mapper/system-root 16G 3.6G 12G 25% /var/lib/mysql
/dev/mapper/system-root 16G 3.6G 12G 25% /opt
/dev/mapper/system-root 16G 3.6G 12G 25% /.snapshots
/dev/mapper/system-root 16G 3.6G 12G 25% /tmp
/dev/mapper/system-root 16G 3.6G 12G 25% /var/tmp
/dev/mapper/system-root 16G 3.6G 12G 25% /var/lib/mailman
/dev/mapper/system-root 16G 3.6G 12G 25% /var/lib/libvirt/images
/dev/mapper/system-root 16G 3.6G 12G 25% /srv
/dev/mapper/system-root 16G 3.6G 12G 25% /var/log
/dev/mapper/system-home 23G 52M 23G 1% /home
tmpfs 201M 16K 201M 1% /run/user/1000
from qdirstat.
shundhammer
commented on May 13, 2024
The Btrfs snapshots are conveniently filtered out, but that seems more like a byproduct of a Btrfs bug to me:
g138:/tmp # grep crossing qdirstat-0.log
2016-12-08 14:36:26.525 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /.snapshots is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.525 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /opt is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.525 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /srv is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.525 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /tmp is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.525 [2664] <Info> DirReadJob.cpp:114 crossingFileSystems(): Found mount point /home on device /dev/mapper/system-home
2016-12-08 14:36:26.525 [2664] <Info> DirReadJob.cpp:114 crossingFileSystems(): Found mount point /dev on device devtmpfs
2016-12-08 14:36:26.525 [2664] <Info> DirReadJob.cpp:114 crossingFileSystems(): Found mount point /proc on device proc
2016-12-08 14:36:26.525 [2664] <Info> DirReadJob.cpp:114 crossingFileSystems(): Found mount point /sys on device sysfs
2016-12-08 14:36:26.525 [2664] <Info> DirReadJob.cpp:114 crossingFileSystems(): Found mount point /run on device tmpfs
2016-12-08 14:36:26.616 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /usr/local is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.616 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /var/cache is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.616 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /var/crash is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.616 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /var/log is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.616 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /var/opt is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.616 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /var/spool is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.616 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /var/tmp is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.625 [2664] <Info> DirReadJob.cpp:112 crossingFileSystems(): Found mount point /.snapshots/1/snapshot
2016-12-08 14:36:26.625 [2664] <Info> DirReadJob.cpp:112 crossingFileSystems(): Found mount point /.snapshots/2/snapshot
2016-12-08 14:36:26.625 [2664] <Info> DirReadJob.cpp:112 crossingFileSystems(): Found mount point /.snapshots/3/snapshot
2016-12-08 14:36:26.625 [2664] <Info> DirReadJob.cpp:112 crossingFileSystems(): Found mount point /.snapshots/4/snapshot
2016-12-08 14:36:26.625 [2664] <Info> DirReadJob.cpp:112 crossingFileSystems(): Found mount point /.snapshots/5/snapshot
2016-12-08 14:36:26.625 [2664] <Info> DirReadJob.cpp:112 crossingFileSystems(): Found mount point /.snapshots/6/snapshot
2016-12-08 14:36:26.625 [2664] <Info> DirReadJob.cpp:112 crossingFileSystems(): Found mount point /.snapshots/7/snapshot
2016-12-08 14:36:26.625 [2664] <Info> DirReadJob.cpp:112 crossingFileSystems(): Found mount point /.snapshots/8/snapshot
2016-12-08 14:36:26.625 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /boot/grub2/i386-pc is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.625 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /boot/grub2/x86_64-efi is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.646 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /var/lib/machines is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.646 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /var/lib/mailman is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.646 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /var/lib/mariadb is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.646 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /var/lib/mysql is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.646 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /var/lib/named is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.646 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /var/lib/pgsql is still on the same device /dev/mapper/system-root
2016-12-08 14:36:26.694 [2664] <Info> DirReadJob.cpp:118 crossingFileSystems(): Mount point /var/lib/libvirt/images is still on the same device /dev/mapper/system-root
They don't show up in /proc/mounts or /etc/mtab or in the output of df:
g138:/tmp # grep -i snap /proc/mounts
/dev/mapper/system-root / btrfs rw,relatime,space_cache,subvolid=259,subvol=/@/.snapshots/1/snapshot 0 0
/dev/mapper/system-root /.snapshots btrfs rw,relatime,space_cache,subvolid=258,subvol=/@/.snapshots 0 0
g138:/tmp # grep -i snap /etc/mtab
/dev/mapper/system-root / btrfs rw,relatime,space_cache,subvolid=259,subvol=/@/.snapshots/1/snapshot 0 0
/dev/mapper/system-root /.snapshots btrfs rw,relatime,space_cache,subvolid=258,subvol=/@/.snapshots 0 0
g138:/tmp # df -h | grep -i snap
/dev/mapper/system-root 16G 3.8G 12G 25% /.snapshots
And forcing a df on them returns a device name -:
g138:/tmp # df -h /.snapshots/*/snapshot
Filesystem Size Used Avail Use% Mounted on
- 16G 3.8G 12G 25% /.snapshots/1/snapshot
- 16G 3.8G 12G 25% /.snapshots/2/snapshot
- 16G 3.8G 12G 25% /.snapshots/3/snapshot
- 16G 3.8G 12G 25% /.snapshots/4/snapshot
- 16G 3.8G 12G 25% /.snapshots/5/snapshot
- 16G 3.8G 12G 25% /.snapshots/6/snapshot
- 16G 3.8G 12G 25% /.snapshots/7/snapshot
- 16G 3.8G 12G 25% /.snapshots/8/snapshot
This is convenient right now because adding snapshots to the directory sums would count every file that is also in a snapshot several times.
If a user still wants to scan a snapshot, he can simply use the normal "Continue reading at mount point" function from the context menu, just like with a normal mount point.
from qdirstat.
shundhammer
commented on May 13, 2024
The qdirstat-cache-writer script now also checks the device names of a mount point and its parent directory, not only their major/minor device numbers; so now it will not stop at Btrfs subvolumes while scanning.
That script uses a more simplistic approach than QDirStat itself: It invokes the df command with that path and parses its output. If the path contains very weird special characters, this may fail, in which case that directory (which at that point is already known to have a different device major/minor number than its parent) is considered a filesystem boundary, and that branch is not scanned.
from qdirstat.
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