02.12.2017 03:27, Qu Wenruo пишет: > > That's the difference between how sub show and quota works. > > For quota, it's per-root owner check. > Means even a file extent is shared between different inodes, if all > inodes are inside the same subvolume, it's counted as exclusive. > And if any of the file extent belongs to other subvolume, then it's > counted as shared. >
Could you also explain how parent qgroup computes exclusive space? I.e. 10:~ # mkfs -t btrfs -f /dev/sdb1 btrfs-progs v4.13.3 See http://btrfs.wiki.kernel.org for more information. Performing full device TRIM /dev/sdb1 (1023.00MiB) ... Label: (null) UUID: b9b0643f-a248-4667-9e69-acf5baaef05b Node size: 16384 Sector size: 4096 Filesystem size: 1023.00MiB Block group profiles: Data: single 8.00MiB Metadata: DUP 51.12MiB System: DUP 8.00MiB SSD detected: no Incompat features: extref, skinny-metadata Number of devices: 1 Devices: ID SIZE PATH 1 1023.00MiB /dev/sdb1 10:~ # mount -t btrfs /dev/sdb1 /mnt 10:~ # cd /mnt 10:/mnt # btrfs quota enable . 10:/mnt # btrfs su cre sub1 Create subvolume './sub1' 10:/mnt # dd if=/dev/urandom of=sub1/file1 bs=1K count=1024 1024+0 records in 1024+0 records out 1048576 bytes (1.0 MB, 1.0 MiB) copied, 0.00833739 s, 126 MB/s 10:/mnt # dd if=/dev/urandom of=sub1/file2 bs=1K count=1024 1024+0 records in 1024+0 records out 1048576 bytes (1.0 MB, 1.0 MiB) copied, 0.0179272 s, 58.5 MB/s 10:/mnt # btrfs subvolume snapshot sub1 sub2 Create a snapshot of 'sub1' in './sub2' 10:/mnt # dd if=/dev/urandom of=sub2/file2 bs=1K count=1024 conv=notrunc 1024+0 records in 1024+0 records out 1048576 bytes (1.0 MB, 1.0 MiB) copied, 0.0348762 s, 30.1 MB/s 10:/mnt # btrfs qgroup show --sync -p . qgroupid rfer excl parent -------- ---- ---- ------ 0/5 16.00KiB 16.00KiB --- 0/256 2.02MiB 1.02MiB --- 0/257 2.02MiB 1.02MiB --- So far so good. This is expected, each subvolume has 1MiB shared and 1MiB exclusive. 10:/mnt # btrfs qgroup create 22/7 /mnt 10:/mnt # btrfs qgroup assign --rescan 0/256 22/7 /mnt Quota data changed, rescan scheduled 10:/mnt # btrfs quota rescan -s /mnt no rescan operation in progress 10:/mnt # btrfs qgroup assign --rescan 0/257 22/7 /mnt Quota data changed, rescan scheduled 10:/mnt # btrfs quota rescan -s /mnt no rescan operation in progress 10:/mnt # btrfs qgroup show --sync -p . qgroupid rfer excl parent -------- ---- ---- ------ 0/5 16.00KiB 16.00KiB --- 0/256 2.02MiB 1.02MiB 22/7 0/257 2.02MiB 1.02MiB 22/7 22/7 3.03MiB 3.03MiB --- 10:/mnt # Oops. Total for 22/7 is correct (1MiB shared + 2 * 1MiB exclusive) but why all data is treated as exclusive here? It does not match your explanation ...
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