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SubjectRe: [RFC PATCH 03/17] btrfs: Check and enable HMZONED mode
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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.

You need this patch to fix it:

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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