[PATCH 3/4] btrfs: zoned: fail mount if the device does not support zone append

[Damien Le Moal]

From: Johannes Thumshirn <johannes.thumshirn at wdc.com>

For zoned btrfs, zone append is mandatory to write to a sequential write
only zone, otherwise parallel writes to the same zone could result in
unaligned write errors.

If a zoned block device does not support zone append (e.g. a dm-crypt
zoned device using a non-NULL IV cypher), fail to mount.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn at wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal at wdc.com>
---
 fs/btrfs/zoned.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index eeb3ebe11d7a..70b23a0d03b1 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -342,6 +342,13 @@ int btrfs_get_dev_zone_info(struct btrfs_device *device)
 	if (!IS_ALIGNED(nr_sectors, zone_sectors))
 		zone_info->nr_zones++;
 
+	if (bdev_is_zoned(bdev) && zone_info->max_zone_append_size == 0) {
+		btrfs_err(fs_info, "zoned: device %pg does not support zone append",
+			  bdev);
+		ret = -EINVAL;
+		goto out;
+	}
+
 	zone_info->seq_zones = bitmap_zalloc(zone_info->nr_zones, GFP_KERNEL);
 	if (!zone_info->seq_zones) {
 		ret = -ENOMEM;
-- 
2.30.2