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Diffstat (limited to 'fs/btrfs/disk-io.c')
-rw-r--r--fs/btrfs/disk-io.c41
1 files changed, 40 insertions, 1 deletions
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 3f43bfea3684..a9aadb2ad525 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1751,6 +1751,7 @@ static int cleaner_kthread(void *arg)
{
struct btrfs_root *root = arg;
int again;
+ struct btrfs_trans_handle *trans;
do {
again = 0;
@@ -1772,7 +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);
@@ -1781,6 +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);
@@ -1789,6 +1799,34 @@ sleep:
__set_current_state(TASK_RUNNING);
}
} while (!kthread_should_stop());
+
+ /*
+ * Transaction kthread is stopped before us and wakes us up.
+ * However we might have started a new transaction and COWed some
+ * tree blocks when deleting unused block groups for example. So
+ * make sure we commit the transaction we started to have a clean
+ * shutdown when evicting the btree inode - if it has dirty pages
+ * when we do the final iput() on it, eviction will trigger a
+ * writeback for it which will fail with null pointer dereferences
+ * since work queues and other resources were already released and
+ * destroyed by the time the iput/eviction/writeback is made.
+ */
+ trans = btrfs_attach_transaction(root);
+ if (IS_ERR(trans)) {
+ if (PTR_ERR(trans) != -ENOENT)
+ btrfs_err(root->fs_info,
+ "cleaner transaction attach returned %ld",
+ PTR_ERR(trans));
+ } else {
+ int ret;
+
+ ret = btrfs_commit_transaction(trans, root);
+ if (ret)
+ btrfs_err(root->fs_info,
+ "cleaner open transaction commit returned %d",
+ ret);
+ }
+
return 0;
}
@@ -2492,6 +2530,7 @@ 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);