@@ -1780,6 +1780,7 @@ struct btrfs_fs_info {
spinlock_t unused_bgs_lock;
struct list_head unused_bgs;
struct mutex unused_bg_unpin_mutex;
+ struct mutex delete_unused_bgs_mutex;
/* For btrfs to record security options */
struct security_mnt_opts security_opts;
@@ -1773,7 +1773,6 @@ static int cleaner_kthread(void *arg)
}
btrfs_run_delayed_iputs(root);
- btrfs_delete_unused_bgs(root->fs_info);
again = btrfs_clean_one_deleted_snapshot(root);
mutex_unlock(&root->fs_info->cleaner_mutex);
@@ -1782,6 +1781,16 @@ static int cleaner_kthread(void *arg)
* needn't do anything special here.
*/
btrfs_run_defrag_inodes(root->fs_info);
+
+ /*
+ * Acquires fs_info->delete_unused_bgs_mutex to avoid racing
+ * with relocation (btrfs_relocate_chunk) and relocation
+ * acquires fs_info->cleaner_mutex (btrfs_relocate_block_group)
+ * after acquiring fs_info->delete_unused_bgs_mutex. So we
+ * can't hold, nor need to, fs_info->cleaner_mutex when deleting
+ * unused block groups.
+ */
+ btrfs_delete_unused_bgs(root->fs_info);
sleep:
if (!try_to_freeze() && !again) {
set_current_state(TASK_INTERRUPTIBLE);
@@ -2489,6 +2498,7 @@ int open_ctree(struct super_block *sb,
spin_lock_init(&fs_info->unused_bgs_lock);
rwlock_init(&fs_info->tree_mod_log_lock);
mutex_init(&fs_info->unused_bg_unpin_mutex);
+ mutex_init(&fs_info->delete_unused_bgs_mutex);
mutex_init(&fs_info->reloc_mutex);
mutex_init(&fs_info->delalloc_root_mutex);
seqlock_init(&fs_info->profiles_lock);
@@ -10003,6 +10003,8 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
}
spin_unlock(&fs_info->unused_bgs_lock);
+ mutex_lock(&root->fs_info->delete_unused_bgs_mutex);
+
/* Don't want to race with allocators so take the groups_sem */
down_write(&space_info->groups_sem);
spin_lock(&block_group->lock);
@@ -10097,6 +10099,7 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
end_trans:
btrfs_end_transaction(trans, root);
next:
+ mutex_unlock(&root->fs_info->delete_unused_bgs_mutex);
btrfs_put_block_group(block_group);
spin_lock(&fs_info->unused_bgs_lock);
}
@@ -2697,6 +2697,20 @@ static int btrfs_relocate_chunk(struct btrfs_root *root,
root = root->fs_info->chunk_root;
extent_root = root->fs_info->extent_root;
+ /*
+ * Prevent races with automatic removal of unused block groups.
+ * After we relocate and before we remove the chunk with offset
+ * chunk_offset, automatic removal of the block group can kick in,
+ * resulting in a failure when calling btrfs_remove_chunk() below.
+ *
+ * Make sure to acquire this mutex before doing a tree search (dev
+ * or chunk trees) to find chunks. Otherwise the cleaner kthread might
+ * call btrfs_remove_chunk() (through btrfs_delete_unused_bgs()) after
+ * we release the path used to search the chunk/dev tree and before
+ * the current task acquires this mutex and calls us.
+ */
+ ASSERT(mutex_is_locked(&root->fs_info->delete_unused_bgs_mutex));
+
ret = btrfs_can_relocate(extent_root, chunk_offset);
if (ret)
return -ENOSPC;
@@ -2745,13 +2759,18 @@ again:
key.type = BTRFS_CHUNK_ITEM_KEY;
while (1) {
+ mutex_lock(&root->fs_info->delete_unused_bgs_mutex);
ret = btrfs_search_slot(NULL, chunk_root, &key, path, 0, 0);
- if (ret < 0)
+ if (ret < 0) {
+ mutex_unlock(&root->fs_info->delete_unused_bgs_mutex);
goto error;
+ }
BUG_ON(ret == 0); /* Corruption */
ret = btrfs_previous_item(chunk_root, path, key.objectid,
key.type);
+ if (ret)
+ mutex_unlock(&root->fs_info->delete_unused_bgs_mutex);
if (ret < 0)
goto error;
if (ret > 0)
@@ -2774,6 +2793,7 @@ again:
else
BUG_ON(ret);
}
+ mutex_unlock(&root->fs_info->delete_unused_bgs_mutex);
if (found_key.offset == 0)
break;
@@ -3230,9 +3250,12 @@ again:
goto error;
}
+ mutex_lock(&fs_info->delete_unused_bgs_mutex);
ret = btrfs_search_slot(NULL, chunk_root, &key, path, 0, 0);
- if (ret < 0)
+ if (ret < 0) {
+ mutex_unlock(&fs_info->delete_unused_bgs_mutex);
goto error;
+ }
/*
* this shouldn't happen, it means the last relocate
@@ -3244,6 +3267,7 @@ again:
ret = btrfs_previous_item(chunk_root, path, 0,
BTRFS_CHUNK_ITEM_KEY);
if (ret) {
+ mutex_unlock(&fs_info->delete_unused_bgs_mutex);
ret = 0;
break;
}
@@ -3252,8 +3276,10 @@ again:
slot = path->slots[0];
btrfs_item_key_to_cpu(leaf, &found_key, slot);
- if (found_key.objectid != key.objectid)
+ if (found_key.objectid != key.objectid) {
+ mutex_unlock(&fs_info->delete_unused_bgs_mutex);
break;
+ }
chunk = btrfs_item_ptr(leaf, slot, struct btrfs_chunk);
@@ -3266,10 +3292,13 @@ again:
ret = should_balance_chunk(chunk_root, leaf, chunk,
found_key.offset);
btrfs_release_path(path);
- if (!ret)
+ if (!ret) {
+ mutex_unlock(&fs_info->delete_unused_bgs_mutex);
goto loop;
+ }
if (counting) {
+ mutex_unlock(&fs_info->delete_unused_bgs_mutex);
spin_lock(&fs_info->balance_lock);
bctl->stat.expected++;
spin_unlock(&fs_info->balance_lock);
@@ -3279,6 +3308,7 @@ again:
ret = btrfs_relocate_chunk(chunk_root,
found_key.objectid,
found_key.offset);
+ mutex_unlock(&fs_info->delete_unused_bgs_mutex);
if (ret && ret != -ENOSPC)
goto error;
if (ret == -ENOSPC) {
@@ -4018,11 +4048,16 @@ again:
key.type = BTRFS_DEV_EXTENT_KEY;
do {
+ mutex_lock(&root->fs_info->delete_unused_bgs_mutex);
ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
- if (ret < 0)
+ if (ret < 0) {
+ mutex_unlock(&root->fs_info->delete_unused_bgs_mutex);
goto done;
+ }
ret = btrfs_previous_item(root, path, 0, key.type);
+ if (ret)
+ mutex_unlock(&root->fs_info->delete_unused_bgs_mutex);
if (ret < 0)
goto done;
if (ret) {
@@ -4036,6 +4071,7 @@ again:
btrfs_item_key_to_cpu(l, &key, path->slots[0]);
if (key.objectid != device->devid) {
+ mutex_unlock(&root->fs_info->delete_unused_bgs_mutex);
btrfs_release_path(path);
break;
}
@@ -4044,6 +4080,7 @@ again:
length = btrfs_dev_extent_length(l, dev_extent);
if (key.offset + length <= new_size) {
+ mutex_unlock(&root->fs_info->delete_unused_bgs_mutex);
btrfs_release_path(path);
break;
}
@@ -4053,6 +4090,7 @@ again:
btrfs_release_path(path);
ret = btrfs_relocate_chunk(root, chunk_objectid, chunk_offset);
+ mutex_unlock(&root->fs_info->delete_unused_bgs_mutex);
if (ret && ret != -ENOSPC)
goto done;
if (ret == -ENOSPC)