On Sat, Aug 17, 2019 at 07:56:50AM +0800, Anand Jain wrote:
On 8/16/19 10:23 PM, Damien Le Moal wrote:
On 2019/08/15 22:46, Anand Jain wrote:
On 8/8/19 5:30 PM, Naohiro Aota wrote:
HMZONED mode cannot be used together with the RAID5/6 profile for now.
Introduce the function btrfs_check_hmzoned_mode() to check this. This
function will also check if HMZONED flag is enabled on the file system and
if the file system consists of zoned devices with equal zone size.
Additionally, as updates to the space cache are in-place, the space cache
cannot be located over sequential zones and there is no guarantees that the
device will have enough conventional zones to store this cache. Resolve
this problem by disabling completely the space cache. This does not
introduces any problems with sequential block groups: all the free space is
located after the allocation pointer and no free space before the pointer.
There is no need to have such cache.
For the same reason, NODATACOW is also disabled.
Also INODE_MAP_CACHE is also disabled to avoid preallocation in the
INODE_MAP_CACHE inode.
A list of incompatibility features with zoned devices. This need better
documentation, may be a table and its reason is better.
Are you referring to the format of the commit message itself ? Or would you like
to see a documentation added to Documentation/filesystems/btrfs.txt ?
Documenting in the commit change log is fine. But it can be better
documented in a listed format as it looks like we have a list of
features which will be incompatible with zoned devices.
more below..
Sure. I will add a table in the next version.
btrfs.txt seems not to have much there. I'm considering to write a new
page in the wiki like:
https://btrfs.wiki.kernel.org/index.php/Feature:Skinny_Metadata
+ if (!hmzoned_devices && incompat_hmzoned) {
+ /* No zoned block device found on HMZONED FS */
+ btrfs_err(fs_info, "HMZONED enabled file system should have zoned devices");
+ ret = -EINVAL;
+ goto out;
When does the HMZONED gets enabled? I presume during mkfs. Where are
the related btrfs-progs patches? Searching for the related btrfs-progs
patches doesn't show up anything in the ML. Looks like I am missing
something, nor the cover letter said anything about the progs part.
Any idea about this comment above?
Thanks, Anand
I just post the updated version of userland side series:
https://lore.kernel.org/linux-btrfs/20190820045258.1571640-1-naohiro.aota@xxxxxxx/T/
Thanks,
Naohiro
