[PATCH 5.12 044/700] btrfs: zoned: bail out if we cant read a reliable write pointer

[Greg Kroah-Hartman]

From: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>

commit 06e1e7f4223c98965fb721b4b1e12083cfbe777e upstream.

If we can't read a reliable write pointer from a sequential zone fail
creating the block group with an I/O error.

Also if the read write pointer is beyond the end of the respective zone,
fail the creation of the block group on this zone with an I/O error.

While this could also happen in real world scenarios with misbehaving
drives, this issue addresses a problem uncovered by fstests' test case
generic/475.

CC: stable@xxxxxxxxxxxxxxx # 5.12+
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/btrfs/zoned.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -1204,6 +1204,13 @@ int btrfs_load_block_group_zone_info(str
 
 	switch (map->type & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
 	case 0: /* single */
+		if (alloc_offsets[0] == WP_MISSING_DEV) {
+			btrfs_err(fs_info,
+			"zoned: cannot recover write pointer for zone %llu",
+				physical);
+			ret = -EIO;
+			goto out;
+		}
 		cache->alloc_offset = alloc_offsets[0];
 		break;
 	case BTRFS_BLOCK_GROUP_DUP:
@@ -1221,6 +1228,13 @@ int btrfs_load_block_group_zone_info(str
 	}
 
 out:
+	if (cache->alloc_offset > fs_info->zone_size) {
+		btrfs_err(fs_info,
+			"zoned: invalid write pointer %llu in block group %llu",
+			cache->alloc_offset, cache->start);
+		ret = -EIO;
+	}
+
 	/* An extent is allocated after the write pointer */
 	if (!ret && num_conventional && last_alloc > cache->alloc_offset) {
 		btrfs_err(fs_info,