Hi,
In the wiki, it's said we can mount subvolumes with different mount
options. nosuid, nodev, rw and ro are listed, as valid generic mount
options.
https://btrfs.wiki.kernel.org/index.php/FAQ#Can_I_mount_subvolumes_with_different_mount_options.3F
But, when I try to mount my subvolume in read only I get an error.
# df
/dev/sdb1 5242880 352 4689856 1% /my_btrfs
# btrfs subvolume list /my_btrfs
ID 257 gen 10 top level 5 path subvol1
# LANG=C mount -t btrfs -o subvol=subvol1,ro /dev/sdb1 /my_btrfs/subvol1_mnt
mount: /dev/sdb1 is already mounted or /my_btrfs/subvol1_mnt busy
/dev/sdb1 is already mounted on /my_btrfs
nodev and nosuid are working.
Is there an error in the wiki, or do I do something wrong ?
Thanks,
Sebastien ROHAUT
Some infos :
# cat /etc/redhat-release
Fedora release 20 (Heisenbug)
# uname -a
Linux localhost.localdomain 3.14.7-200.fc20.x86_64 #1 SMP Wed Jun 11
22:38:05 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
# btrfs --version
Btrfs v3.14.1
# btrfs fi show
Label: none uuid: 66e0f120-e478-4cac-b04a-82a0ffc4d6ce
Total devices 1 FS bytes used 208.00KiB
devid 1 size 5.00GiB used 548.00MiB path /dev/sdb1
Btrfs v3.14.1
# dmesg|grep -i btrfs
[ 2.753052] Btrfs loaded
[ 2.766655] BTRFS: device fsid 66e0f120-e478-4cac-b04a-82a0ffc4d6ce
devid 1 transid 9 /dev/sdb1
[ 36.382921] BTRFS: device fsid 66e0f120-e478-4cac-b04a-82a0ffc4d6ce
devid 1 transid 9 /dev/sdb1
[ 36.389497] BTRFS info (device sdb1): disk space caching is enabled
[ 36.393462] SELinux: initialized (dev sdb1, type btrfs), uses xattr
[ 860.375237] BTRFS: device fsid 66e0f120-e478-4cac-b04a-82a0ffc4d6ce
devid 1 transid 9 /dev/sdb1
[ 1141.451952] BTRFS: device fsid 66e0f120-e478-4cac-b04a-82a0ffc4d6ce
devid 1 transid 10 /dev/sdb1
[ 1379.802221] BTRFS info (device sdb1): disk space caching is enabled
[ 1513.815988] BTRFS info (device sdb1): disk space caching is enabled
[ 1529.839598] BTRFS: device fsid 66e0f120-e478-4cac-b04a-82a0ffc4d6ce
devid 1 transid 11 /dev/sdb1
[ 1624.310822] BTRFS: device fsid 66e0f120-e478-4cac-b04a-82a0ffc4d6ce
devid 1 transid 11 /dev/sdb1
[ 1650.630700] BTRFS: device fsid 66e0f120-e478-4cac-b04a-82a0ffc4d6ce
devid 1 transid 11 /dev/sdb1
[ 2297.318435] BTRFS: device fsid 66e0f120-e478-4cac-b04a-82a0ffc4d6ce
devid 1 transid 11 /dev/sdb1
[ 2305.110964] BTRFS: device fsid 66e0f120-e478-4cac-b04a-82a0ffc4d6ce
devid 1 transid 11 /dev/sdb1
[ 2332.863021] BTRFS: device fsid 66e0f120-e478-4cac-b04a-82a0ffc4d6ce
devid 1 transid 12 /dev/sdb1
[ 2344.573903] BTRFS: device fsid 66e0f120-e478-4cac-b04a-82a0ffc4d6ce
devid 1 transid 12 /dev/sdb1
[ 2348.597860] BTRFS: device fsid 66e0f120-e478-4cac-b04a-82a0ffc4d6ce
devid 1 transid 12 /dev/sdb1
[ 2580.620032] BTRFS: device fsid 66e0f120-e478-4cac-b04a-82a0ffc4d6ce
devid 1 transid 13 /dev/sdb1
[ 2645.162881] BTRFS: device fsid 66e0f120-e478-4cac-b04a-82a0ffc4d6ce
devid 1 transid 13 /dev/sdb1
[ 2706.458681] BTRFS: device fsid 66e0f120-e478-4cac-b04a-82a0ffc4d6ce
devid 1 transid 13 /dev/sdb1
[ 2727.745959] BTRFS: device fsid 66e0f120-e478-4cac-b04a-82a0ffc4d6ce
devid 1 transid 13 /dev/sdb1
[ 2797.601678] BTRFS: device fsid 66e0f120-e478-4cac-b04a-82a0ffc4d6ce
devid 1 transid 13 /dev/sdb1
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