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SubjectRe: [RFC PATCH 03/17] btrfs: Check and enable HMZONED mode
On Fri, Aug 10, 2018 at 02:25:33PM +0200, Hannes Reinecke wrote:
> On 08/09/2018 08:04 PM, Naohiro Aota wrote:
> > HMZONED mode cannot be used together with the RAID5/6 profile. 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.
> >
> > Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
> > Signed-off-by: Naohiro Aota <naota@elisp.net>
> > ---
> > fs/btrfs/ctree.h | 3 ++
> > fs/btrfs/dev-replace.c | 7 ++++
> > fs/btrfs/disk-io.c | 7 ++++
> > fs/btrfs/super.c | 12 +++---
> > fs/btrfs/volumes.c | 87 ++++++++++++++++++++++++++++++++++++++++++
> > fs/btrfs/volumes.h | 1 +
> > 6 files changed, 112 insertions(+), 5 deletions(-)
> >
> > diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> > index 66f1d3895bca..14f880126532 100644
> > --- a/fs/btrfs/ctree.h
> > +++ b/fs/btrfs/ctree.h
> > @@ -763,6 +763,9 @@ struct btrfs_fs_info {
> > struct btrfs_root *uuid_root;
> > struct btrfs_root *free_space_root;
> >
> > + /* Zone size when in HMZONED mode */
> > + u64 zone_size;
> > +
> > /* the log root tree is a directory of all the other log roots */
> > struct btrfs_root *log_root_tree;
> >
> > diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
> > index dec01970d8c5..839a35008fd8 100644
> > --- a/fs/btrfs/dev-replace.c
> > +++ b/fs/btrfs/dev-replace.c
> > @@ -202,6 +202,13 @@ static int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
> > return PTR_ERR(bdev);
> > }
> >
> > + if ((bdev_zoned_model(bdev) == BLK_ZONED_HM &&
> > + !btrfs_fs_incompat(fs_info, HMZONED)) ||
> > + (!bdev_is_zoned(bdev) && btrfs_fs_incompat(fs_info, HMZONED))) {
> > + ret = -EINVAL;
> > + goto error;
> > + }
> > +
> > filemap_write_and_wait(bdev->bd_inode->i_mapping);
> >
> > devices = &fs_info->fs_devices->devices;
> > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> > index 5124c15705ce..14f284382ba7 100644
> > --- a/fs/btrfs/disk-io.c
> > +++ b/fs/btrfs/disk-io.c
> > @@ -3057,6 +3057,13 @@ int open_ctree(struct super_block *sb,
> >
> > btrfs_free_extra_devids(fs_devices, 1);
> >
> > + ret = btrfs_check_hmzoned_mode(fs_info);
> > + if (ret) {
> > + btrfs_err(fs_info, "failed to init hmzoned mode: %d",
> > + ret);
> > + goto fail_block_groups;
> > + }
> > +
> > ret = btrfs_sysfs_add_fsid(fs_devices, NULL);
> > if (ret) {
> > btrfs_err(fs_info, "failed to init sysfs fsid interface: %d",
> > diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> > index 5fdd95e3de05..cc812e459197 100644
> > --- a/fs/btrfs/super.c
> > +++ b/fs/btrfs/super.c
> > @@ -435,11 +435,13 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
> > bool saved_compress_force;
> > int no_compress = 0;
> >
> > - cache_gen = btrfs_super_cache_generation(info->super_copy);
> > - if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE))
> > - btrfs_set_opt(info->mount_opt, FREE_SPACE_TREE);
> > - else if (cache_gen)
> > - btrfs_set_opt(info->mount_opt, SPACE_CACHE);
> > + if (!btrfs_fs_incompat(info, HMZONED)) {
> > + cache_gen = btrfs_super_cache_generation(info->super_copy);
> > + if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE))
> > + btrfs_set_opt(info->mount_opt, FREE_SPACE_TREE);
> > + else if (cache_gen)
> > + btrfs_set_opt(info->mount_opt, SPACE_CACHE);
> > + }
> >
> > /*
> > * Even the options are empty, we still need to do extra check
> > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> > index 35b3a2187653..ba7ebb80de4d 100644
> > --- a/fs/btrfs/volumes.c
> > +++ b/fs/btrfs/volumes.c
> > @@ -1293,6 +1293,80 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
> > return ret;
> > }
> >
> > +int btrfs_check_hmzoned_mode(struct btrfs_fs_info *fs_info)
> > +{
> > + struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
> > + struct btrfs_device *device;
> > + u64 hmzoned_devices = 0;
> > + u64 nr_devices = 0;
> > + u64 zone_size = 0;
> > + int incompat_hmzoned = btrfs_fs_incompat(fs_info, HMZONED);
> > + int ret = 0;
> > +
> > + /* Count zoned devices */
> > + list_for_each_entry(device, &fs_devices->devices, dev_list) {
> > + if (!device->bdev)
> > + continue;
> > + if (bdev_zoned_model(device->bdev) == BLK_ZONED_HM ||
> > + (bdev_zoned_model(device->bdev) == BLK_ZONED_HA &&
> > + incompat_hmzoned)) {
> > + hmzoned_devices++;
> > + if (!zone_size) {
> > + zone_size = device->zone_size;
> > + } else if (device->zone_size != zone_size) {
> > + btrfs_err(fs_info,
> > + "Zoned block devices must have equal zone sizes");
> > + ret = -EINVAL;
> > + goto out;
> > + }
> > + }
> > + nr_devices++;
> > + }
> > +
> > + if (!hmzoned_devices && incompat_hmzoned) {
> > + /* No zoned block device, disable HMZONED */
> > + btrfs_err(fs_info, "HMZONED enabled file system should have zoned devices");
> > + ret = -EINVAL;
> > + goto out;
> > + }
> > +
> > + fs_info->zone_size = zone_size;
> > +
> > + if (hmzoned_devices != nr_devices) {
> > + btrfs_err(fs_info,
> > + "zoned devices mixed with regular devices");
> > + ret = -EINVAL;
> > + goto out;
> > + }
> > +
> This breaks existing setups; as we're not checking if the device
> specified by fs_info is a zoned device we'll fail here for normal devices.

Ah, I forgot to deel with the normal devices when I convert HMZONED
mount flag to incompat flag.

> You need this patch to fix it:

Thank you for fixing this. It's exactly what I wanted to do. I'll fix
in the next version.

Regards,
Naohiro

> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 43eaf0142062..8609776c9a9e 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -1314,6 +1314,9 @@ int btrfs_check_hmzoned_mode(struct btrfs_fs_info
> *fs_info)
> int incompat_hmzoned = btrfs_fs_incompat(fs_info, HMZONED);
> int ret = 0;
>
> + if (!incompat_hmzoned)
> + return 0;
> +
> /* Count zoned devices */
> list_for_each_entry(device, &fs_devices->devices, dev_list) {
> if (!device->bdev)
>
>
> Cheers,
>
> Hannes
> --
> Dr. Hannes Reinecke zSeries & Storage
> hare@suse.com +49 911 74053 688
> SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
> GF: F. Imendörffer, J. Smithard, D. Upmanyu, G. Norton
> HRB 21284 (AG Nürnberg)

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