Hiya, please consider this: ~# truncate -s1G ./a ~# mkfs.btrfs ./a ~# sudo mount -o loop ./a /mnt/1 ~# cd /mnt/1 /mnt/1# ls /mnt/1# btrfs sub c A Create subvolume ''./A'' /mnt/1# btrfs sub c A/B Create subvolume ''A/B'' /mnt/1# touch A/inA A/B/inB /mnt/1# btrfs sub snap A A.snap Create a snapshot of ''A'' in ''./A.snap'' /mnt/1# zmodload zsh/stat /mnt/1# zstat +device ./**/* . 25 A 26 A/B 27 A/B/inB 27 A/inA 26 A.snap 28 A.snap/B 23 A.snap/inA 28 Why does A.snap/B have a different st_dev from A.snap''s? Also: /mnt/1# touch A.snap/B/foo touch: cannot touch `A.snap/B/foo'': Permission denied I can rmdir that directory OK though. Also note that the permissions are different: /mnt/1# ll A total 0 drwx------ 1 root root 6 Jun 2 00:54 B/ -rw-r--r-- 1 root root 0 Jun 2 00:54 inA /mnt/1# ll A.snap total 0 drwxr-xr-x 1 root root 0 Jun 2 01:29 B/ -rw-r--r-- 1 root root 0 Jun 2 00:54 inA If I create another snap of A or A.snap, the "B" in there gets the same st_dev (23). /mnt/1# btrfs sub create A.snap/B/C Create subvolume ''A.snap/B/C'' ERROR: cannot create subvolume # btrfs sub snap A.snap/B B.snap ERROR: ''A.snap/B'' is not a subvolume -- Stephane -- 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
2011-06-02 01:39:41 +0100, Stephane Chazelas: [...]> /mnt/1# zstat +device ./**/* > . 25 > A 26 > A/B 27 > A/B/inB 27 > A/inA 26 > A.snap 28 > A.snap/B 23 > A.snap/inA 28 > > Why does A.snap/B have a different st_dev from A.snap''s?[...]> If I create another snap of A or A.snap, the "B" in there gets > the same st_dev (23).[...] And same inode, ctime, mtime, atime... And when I create a new snapshot, all those (regardless of where they are) have their times updated at once. I also noticed the st_nlink is always one but then came accross http://thread.gmane.org/gmane.comp.file-systems.btrfs/4580 -- Stephane -- 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