btrfs: zoned: defer loading zone info after opening trees

This is a preparation patch to implement zone emulation on a regular
device.

To emulate a zoned filesystem on a regular (non-zoned) device, we need to
decide an emulated zone size. Instead of making it a compile-time static
value, we'll make it configurable at mkfs time. Since we have one zone ==
one device extent restriction, we can determine the emulated zone size
from the size of a device extent. We can extend btrfs_get_dev_zone_info()
to show a regular device filled with conventional zones once the zone size
is decided.

The current call site of btrfs_get_dev_zone_info() during the mount process
is earlier than loading the file system trees so that we don't know the
size of a device extent at this point. Thus we can't slice a regular device
to conventional zones.

This patch introduces btrfs_get_dev_zone_info_all_devices to load the zone
info for all the devices. And, it places this function in open_ctree()
after loading the trees.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 71fab77..2b6a3df 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3333,6 +3333,19 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
        if (ret)
                goto fail_tree_roots;
 
+       /*
+        * Get zone type information of zoned block devices. This will also
+        * handle emulation of a zoned filesystem if a regular device has the
+        * zoned incompat feature flag set.
+        */
+       ret = btrfs_get_dev_zone_info_all_devices(fs_info);
+       if (ret) {
+               btrfs_err(fs_info,
+                         "zoned: failed to read device zone info: %d",
+                         ret);
+               goto fail_block_groups;
+       }
+
        /*
         * If we have a uuid root and we're not being told to rescan we need to
         * check the generation here so we can set the

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 3948f5b..07cd474 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -669,10 +669,6 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
        clear_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
        device->mode = flags;
 
-       ret = btrfs_get_dev_zone_info(device);
-       if (ret != 0)
-               goto error_free_page;
-
        fs_devices->open_devices++;
        if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state) &&
            device->devid != BTRFS_DEV_REPLACE_DEVID) {

diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index 41d27fe..0b1b1f3 100644 (file)
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -143,6 +143,31 @@ static int btrfs_get_dev_zones(struct btrfs_device *device, u64 pos,
        return 0;
 }
 
+int btrfs_get_dev_zone_info_all_devices(struct btrfs_fs_info *fs_info)
+{
+       struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
+       struct btrfs_device *device;
+       int ret = 0;
+
+       /* fs_info->zone_size might not set yet. Use the incomapt flag here. */
+       if (!btrfs_fs_incompat(fs_info, ZONED))
+               return 0;
+
+       mutex_lock(&fs_devices->device_list_mutex);
+       list_for_each_entry(device, &fs_devices->devices, dev_list) {
+               /* We can skip reading of zone info for missing devices */
+               if (!device->bdev)
+                       continue;
+
+               ret = btrfs_get_dev_zone_info(device);
+               if (ret)
+                       break;
+       }
+       mutex_unlock(&fs_devices->device_list_mutex);
+
+       return ret;
+}
+
 int btrfs_get_dev_zone_info(struct btrfs_device *device)
 {
        struct btrfs_zoned_device_info *zone_info = NULL;

diff --git a/fs/btrfs/zoned.h b/fs/btrfs/zoned.h
index 8abe2f8..eb47b7a 100644 (file)
--- a/fs/btrfs/zoned.h
+++ b/fs/btrfs/zoned.h
@@ -25,6 +25,7 @@ struct btrfs_zoned_device_info {
 #ifdef CONFIG_BLK_DEV_ZONED
 int btrfs_get_dev_zone(struct btrfs_device *device, u64 pos,
                       struct blk_zone *zone);
+int btrfs_get_dev_zone_info_all_devices(struct btrfs_fs_info *fs_info);
 int btrfs_get_dev_zone_info(struct btrfs_device *device);
 void btrfs_destroy_dev_zone_info(struct btrfs_device *device);
 int btrfs_check_zoned_mode(struct btrfs_fs_info *fs_info);
@@ -42,6 +43,11 @@ static inline int btrfs_get_dev_zone(struct btrfs_device *device, u64 pos,
        return 0;
 }
 
+static inline int btrfs_get_dev_zone_info_all_devices(struct btrfs_fs_info *fs_info)
+{
+       return 0;
+}
+
 static inline int btrfs_get_dev_zone_info(struct btrfs_device *device)
 {
        return 0;