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.

In summary, HMZONED will disable:

| Disabled features | Reason                                              |
|-------------------+-----------------------------------------------------|
| RAID5/6           | 1) Non-full stripe write cause overwriting of       |
|                   | parity block                                        |
|                   | 2) Rebuilding on high capacity volume (usually with |
|                   | SMR) can lead to higher failure rate                |
|-------------------+-----------------------------------------------------|
| space_cache (v1)  | In-place updating                                   |
| NODATACOW         | In-place updating                                   |
|-------------------+-----------------------------------------------------|
| tree-log          | Partial write out of metadata creates write holes   |
|-------------------+-----------------------------------------------------|
| fallocate         | Reserved extent will be a write hole                |
| INODE_MAP_CACHE   | Need pre-allocation. (and will be deprecated?)      |
|-------------------+-----------------------------------------------------|
| MIXED_BG          | Allocated metadata region will be write holes for   |
|                   | data writes                                         |
| async checksum    | Not to mix up bios by multiple workers              |

Signed-off-by: Damien Le Moal <redacted>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
---
 fs/btrfs/ctree.h       |  3 ++
 fs/btrfs/dev-replace.c |  8 +++++
 fs/btrfs/disk-io.c     |  8 +++++
 fs/btrfs/hmzoned.c     | 67 ++++++++++++++++++++++++++++++++++++++++++
 fs/btrfs/hmzoned.h     | 18 ++++++++++++
 fs/btrfs/super.c       |  1 +
 fs/btrfs/volumes.c     |  5 ++++
 7 files changed, 110 insertions(+)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 94660063a162..221259737703 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h

@@ -712,6 +712,9 @@ 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 6b2e9aa83ffa..2cc3ac4d101d 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c

@@ -20,6 +20,7 @@
 #include "rcu-string.h"
 #include "dev-replace.h"
 #include "sysfs.h"
+#include "hmzoned.h"
 
 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 				       int scrub_ret);

@@ -201,6 +202,13 @@ static int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 		return PTR_ERR(bdev);
 	}
 
+	if (!btrfs_check_device_zone_type(fs_info, bdev)) {
+		btrfs_err(fs_info,
+			  "zone type of target device mismatch with the filesystem!");
+		ret = -EINVAL;
+		goto error;
+	}
+
 	sync_blockdev(bdev);
 
 	devices = &fs_info->fs_devices->devices;

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 97beb351a10c..3f5ea92f546c 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c

@@ -40,6 +40,7 @@
 #include "compression.h"
 #include "tree-checker.h"
 #include "ref-verify.h"
+#include "hmzoned.h"
 
 #define BTRFS_SUPER_FLAG_SUPP	(BTRFS_HEADER_FLAG_WRITTEN |\
 				 BTRFS_HEADER_FLAG_RELOC |\

@@ -3121,6 +3122,13 @@ 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/hmzoned.c b/fs/btrfs/hmzoned.c
index 23bf58d3d7bb..ca58eee08a70 100644
--- a/fs/btrfs/hmzoned.c
+++ b/fs/btrfs/hmzoned.c

@@ -157,3 +157,70 @@ int btrfs_get_dev_zone(struct btrfs_device *device, u64 pos,
 
 	return 0;
 }
+
+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_info->zone_size;
+			} else if (device->zone_info->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 found on HMZONED FS */
+		btrfs_err(fs_info, "HMZONED enabled file system should have zoned devices");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (!hmzoned_devices && !incompat_hmzoned)
+		goto out;
+
+	fs_info->zone_size = zone_size;
+
+	if (hmzoned_devices != nr_devices) {
+		btrfs_err(fs_info,
+			  "zoned devices cannot be mixed with regular devices");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/*
+	 * stripe_size is always aligned to BTRFS_STRIPE_LEN in
+	 * __btrfs_alloc_chunk(). Since we want stripe_len == zone_size,
+	 * check the alignment here.
+	 */
+	if (!IS_ALIGNED(zone_size, BTRFS_STRIPE_LEN)) {
+		btrfs_err(fs_info,
+			  "zone size is not aligned to BTRFS_STRIPE_LEN");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	btrfs_info(fs_info, "HMZONED mode enabled, zone size %llu B",
+		   fs_info->zone_size);
+out:
+	return ret;
+}

diff --git a/fs/btrfs/hmzoned.h b/fs/btrfs/hmzoned.h
index ffc70842135e..29cfdcabff2f 100644
--- a/fs/btrfs/hmzoned.h
+++ b/fs/btrfs/hmzoned.h

@@ -9,6 +9,8 @@
 #ifndef BTRFS_HMZONED_H
 #define BTRFS_HMZONED_H
 
+#include <linux/blkdev.h>
+
 struct btrfs_zoned_device_info {
 	/*
 	 * Number of zones, zone size and types of zones if bdev is a

@@ -25,6 +27,7 @@ int btrfs_get_dev_zone(struct btrfs_device *device, u64 pos,
 		       struct blk_zone *zone, gfp_t gfp_mask);
 int btrfs_get_dev_zone_info(struct btrfs_device *device);
 void btrfs_destroy_dev_zone_info(struct btrfs_device *device);
+int btrfs_check_hmzoned_mode(struct btrfs_fs_info *fs_info);