btrfs: zoned: disable metadata overcommit for zoned

[ Upstream commit 79417d040f4f77b19c701bccc23013b9cdac358d ]

The metadata overcommit makes the space reservation flexible but it is also
harmful to active zone tracking. Since we cannot finish a block group from
the metadata allocation context, we might not activate a new block group
and might not be able to actually write out the overcommit reservations.

So, disable metadata overcommit for zoned filesystems. We will ensure
the reservations are under active_total_bytes in the following patches.

CC: stable@vger.kernel.org # 5.16+
Fixes: afba2bc036b0 ("btrfs: zoned: implement active zone tracking")
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index b87931a458ebb7db08126f9cee0a0e1cea817507..56a7c99fc03eb4c0076f6457e7ee89595703c82d 100644 (file)
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -340,7 +340,10 @@ int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
                return 0;
 
        used = btrfs_space_info_used(space_info, true);
-       avail = calc_available_free_space(fs_info, space_info, flush);
+       if (btrfs_is_zoned(fs_info) && (space_info->flags & BTRFS_BLOCK_GROUP_METADATA))
+               avail = 0;
+       else
+               avail = calc_available_free_space(fs_info, space_info, flush);
 
        if (used + bytes < space_info->total_bytes + avail)
                return 1;