The extent allocation tree is recursive, it may change after
update_cowonly_root is called. So we shouldn't update extent
tree's commit_root directly in update_cowonly_root.
Signed-off-by: Yan Zheng <zheng....@oracle.com>
---
diff -urp 1/fs/btrfs/ctree.h 2/fs/btrfs/ctree.h
--- 1/fs/btrfs/ctree.h 2009-07-29 10:03:04.258858190 +0800
+++ 2/fs/btrfs/ctree.h 2009-07-30 10:06:08.837786432 +0800
@@ -827,6 +827,7 @@ struct btrfs_fs_info {
struct mutex drop_mutex;
struct mutex volume_mutex;
struct mutex tree_reloc_mutex;
+ struct rw_semaphore extent_commit_sem;
/*
* this protects the ordered operations list only while we are
@@ -961,9 +962,6 @@ struct btrfs_root {
/* the node lock is held while changing the node pointer */
spinlock_t node_lock;
- /* taken when updating the commit root */
- struct rw_semaphore commit_root_sem;
-
struct extent_buffer *commit_root;
struct btrfs_root *log_root;
struct btrfs_root *reloc_root;
diff -urp 1/fs/btrfs/disk-io.c 2/fs/btrfs/disk-io.c
--- 1/fs/btrfs/disk-io.c 2009-07-29 10:03:04.260858403 +0800
+++ 2/fs/btrfs/disk-io.c 2009-07-30 10:07:27.230037079 +0800
@@ -907,7 +907,6 @@ static int __setup_root(u32 nodesize, u3
spin_lock_init(&root->inode_lock);
mutex_init(&root->objectid_mutex);
mutex_init(&root->log_mutex);
- init_rwsem(&root->commit_root_sem);
init_waitqueue_head(&root->log_writer_wait);
init_waitqueue_head(&root->log_commit_wait[0]);
init_waitqueue_head(&root->log_commit_wait[1]);
@@ -1624,6 +1623,7 @@ struct btrfs_root *open_ctree(struct sup
mutex_init(&fs_info->cleaner_mutex);
mutex_init(&fs_info->volume_mutex);
mutex_init(&fs_info->tree_reloc_mutex);
+ init_rwsem(&fs_info->extent_commit_sem);
btrfs_init_free_cluster(&fs_info->meta_alloc_cluster);
btrfs_init_free_cluster(&fs_info->data_alloc_cluster);
diff -urp 1/fs/btrfs/extent-tree.c 2/fs/btrfs/extent-tree.c
--- 1/fs/btrfs/extent-tree.c 2009-07-29 10:03:04.264855268 +0800
+++ 2/fs/btrfs/extent-tree.c 2009-07-30 10:08:34.582036148 +0800
@@ -267,7 +267,7 @@ static int caching_kthread(void *data)
last = max_t(u64, block_group->key.objectid, BTRFS_SUPER_INFO_OFFSET);
again:
/* need to make sure the commit_root doesn't disappear */
- down_read(&fs_info->extent_root->commit_root_sem);
+ down_read(&fs_info->extent_commit_sem);
/*
* We don't want to deadlock with somebody trying to allocate a new
@@ -304,7 +302,7 @@ again:
if (need_resched()) {
btrfs_release_path(fs_info->extent_root, path);
- up_read(&fs_info->extent_root->commit_root_sem);
+ up_read(&fs_info->extent_commit_sem);
cond_resched();
goto again;
}
@@ -345,7 +343,7 @@ next:
err:
btrfs_free_path(path);
- up_read(&fs_info->extent_root->commit_root_sem);
+ up_read(&fs_info->extent_commit_sem);
atomic_dec(&block_group->space_info->caching_threads);
wake_up(&block_group->caching_q);
diff -urp 1/fs/btrfs/transaction.c 2/fs/btrfs/transaction.c
--- 1/fs/btrfs/transaction.c 2009-07-29 10:03:04.481858667 +0800
+++ 2/fs/btrfs/transaction.c 2009-07-30 10:18:04.331033676 +0800
@@ -42,10 +42,8 @@ static noinline void put_transaction(str
static noinline void switch_commit_root(struct btrfs_root *root)
{
- down_write(&root->commit_root_sem);
free_extent_buffer(root->commit_root);
root->commit_root = btrfs_root_node(root);
- up_write(&root->commit_root_sem);
}
/*
@@ -466,7 +464,10 @@ static int update_cowonly_root(struct bt
ret = btrfs_write_dirty_block_groups(trans, root);
BUG_ON(ret);
}
- switch_commit_root(root);
+
+ if (root != root->fs_info->extent_root)
+ switch_commit_root(root);
+
return 0;
}
@@ -499,6 +500,11 @@ static noinline int commit_cowonly_roots
update_cowonly_root(trans, root);
}
+
+ down_write(&fs_info->extent_commit_sem);
+ switch_commit_root(fs_info->extent_root);
+ up_write(&fs_info->extent_commit_sem);
+
return 0;
}
--
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