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tNff_uRAsvImcFPNeEjVVm5nA6PwdiG9 X-Proofpoint-ORIG-GUID: tNff_uRAsvImcFPNeEjVVm5nA6PwdiG9 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 02/10/2023 20:57, David Sterba wrote: > On Thu, Sep 28, 2023 at 09:09:47AM +0800, Anand Jain wrote: >> Guilherme's previous work [1] aimed at the mounting of cloned devices >> using a superblock flag SINGLE_DEV during mkfs. >> [1] https://lore.kernel.org/linux-btrfs/20230831001544.3379273-1-gpiccoli@igalia.com/ The link should go at SOB with prefix Link:. >> >> Building upon this work, here is in memory only approach. As it mounts >> we determine if the same fsid is already mounted if then we generate a >> random temp fsid which shall be used the mount, in memory only not >> written to the disk. We distinguish devices by devt. >> >> Example: >> $ fallocate -l 300m ./disk1.img :0 >> $ mkfs.btrfs -f ./disk1.img :0 >> $ cp ./disk1.img ./disk2.img :0 >> $ cp ./disk1.img ./disk3.img :0 >> $ mount -o loop ./disk1.img /btrfs :0 >> $ mount -o ./disk2.img /btrfs1 :0 >> $ mount -o ./disk3.img /btrfs2 :0 > > I'm confused what the ":0" are supposed to mean, is it some artifact of > your editor? Oh, sorry for the confusion. It is the return status of the command. I have some local scripts to collect the output. Could you pls remove ":0", or I'll if there is a reroll. Thanks, Anand > >> >> $ btrfs fi show -m :0 >> Label: none uuid: 4a212b48-1bec-46a5-938a-783c8c1f0b02 >> Total devices 1 FS bytes used 144.00KiB >> devid 1 size 300.00MiB used 88.00MiB path /dev/loop0 >> >> Label: none uuid: adabf2fe-5515-4ad0-95b4-7b1609218c16 >> Total devices 1 FS bytes used 144.00KiB >> devid 1 size 300.00MiB used 88.00MiB path /dev/loop1 >> >> Label: none uuid: 1d77d0df-7d92-439e-adbd-20b9b86fdedb >> Total devices 1 FS bytes used 144.00KiB >> devid 1 size 300.00MiB used 88.00MiB path /dev/loop2 >> >> Co-developed-by: Guilherme G. Piccoli >> Signed-off-by: Anand Jain