[PATCH 5.13 047/800] btrfs: zoned: bail out if we cant read a reliable write pointer

From: Greg Kroah-Hartman
Date: Mon Jul 12 2021 - 04:11:02 EST


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,