@@ -10010,8 +10010,10 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
block_group = list_first_entry(&fs_info->unused_bgs,
struct btrfs_block_group_cache,
bg_list);
- space_info = block_group->space_info;
list_del_init(&block_group->bg_list);
+
+ space_info = block_group->space_info;
+
if (ret || btrfs_mixed_space_info(space_info)) {
btrfs_put_block_group(block_group);
continue;
@@ -10025,7 +10027,8 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
spin_lock(&block_group->lock);
if (block_group->reserved ||
btrfs_block_group_used(&block_group->item) ||
- block_group->ro) {
+ block_group->ro ||
+ list_is_singular(&block_group->list)) {
/*
* We want to bail if we made new allocations or have
* outstanding allocations in this block group. We do
Reproduce: (In integration-4.3 branch) TEST_DEV=(/dev/vdg /dev/vdh) TEST_DIR=/mnt/tmp umount "$TEST_DEV" >/dev/null mkfs.btrfs -f -d raid1 "${TEST_DEV[@]}" mount -o nospace_cache "$TEST_DEV" "$TEST_DIR" umount "$TEST_DEV" mount -o nospace_cache "$TEST_DEV" "$TEST_DIR" btrfs filesystem usage $TEST_DIR We can see the data chunk changed from raid1 to single: # btrfs filesystem usage $TEST_DIR Data,single: Size:8.00MiB, Used:0.00B /dev/vdg 8.00MiB # Reason: When a empty filesystem mount with -o nospace_cache, the last data blockgroup will be auto-removed in umount. Then if we mount it again, there is no data chunk in the filesystem, so the only available data profile is 0x0, result is all new chunks are created as single type. Fix: Don't auto-delete last blockgroup for a raid type. Test: Test by above script, and confirmed the logic by debug output. Changelog v3->v4: 1: Avoid down_read() in spin_lock context. Noticed-by: Chris Mason <clm@fb.com> Changelog v2->v3: 1: Use list_is_singular() instead of block_group->list.next == block_group->list.prev Suggested-by: Jeff Mahoney <jeffm@suse.com> Changelog v1->v2: 1: Put code of checking block_group->list into semaphore of space_info->groups_sem. Noticed-by: Filipe Manana <fdmanana@gmail.com> Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com> --- fs/btrfs/extent-tree.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)