Relocation code will drop btrfs_root::reloc_root as soon as
merge_reloc_root() finishes.
However later qgroup code will need to access btrfs_root::reloc_root
after merge_reloc_root() for delayed subtree rescan.
So alter the timming of resetting btrfs_root:::reloc_root, make it
happens after transaction commit.
With this patch, we will introduce a new btrfs_root::state,
BTRFS_ROOT_DEAD_RELOC_TREE, to info part of btrfs_root::reloc_tree user
that although btrfs_root::reloc_tree is still non-NULL, but still it's
not used any more.
The lifespan of btrfs_root::reloc tree will become:
Old behavior | New
------------------------------------------------------------------------
btrfs_init_reloc_root() --- | btrfs_init_reloc_root() ---
set reloc_root | | set reloc_root |
| | |
| | |
merge_reloc_root() | | merge_reloc_root() |
|- btrfs_update_reloc_root() --- | |- btrfs_update_reloc_root() -+-
clear btrfs_root::reloc_root | set ROOT_DEAD_RELOC_TREE |
| record root into dirty |
| roots rbtree |
| |
| reloc_block_group() Or |
| btrfs_recover_relocation() |
| | After transaction commit |
| |- clean_dirty_subvols() ---
| clear btrfs_root::reloc_root
During ROOT_DEAD_RELOC_TREE set lifespan, the only user of
btrfs_root::reloc_tree should be qgroup.
Since reloc root needs a longer life-span, this patch will also delay
btrfs_drop_snapshot() call.
Now btrfs_drop_snapshot() is called in clean_dirty_subvols().
This patch will increase the size of btrfs_root by 16 bytes.
Signed-off-by: Qu Wenruo <w...@suse.com>
---
fs/btrfs/ctree.h | 15 ++++++++
fs/btrfs/disk-io.c | 1 +
fs/btrfs/relocation.c | 86 ++++++++++++++++++++++++++++++++++---------
3 files changed, 85 insertions(+), 17 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 0a68cf7032f5..865ce9531d96 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1195,6 +1195,13 @@ enum {
BTRFS_ROOT_MULTI_LOG_TASKS,
BTRFS_ROOT_DIRTY,
BTRFS_ROOT_DELETING,
+
+ /*
+ * Reloc tree is orphan, only kept here for qgroup delayed subtree scan
+ *
+ * Set for the subvolume tree owning the reloc tree.
+ */
+ BTRFS_ROOT_DEAD_RELOC_TREE,
};
/*
@@ -1307,6 +1314,14 @@ struct btrfs_root {
struct list_head ordered_root;
u64 nr_ordered_extents;
+ /*
+ * Not empty if this subvolume root has gone through tree block swap
+ * (relocation)
+ *
+ * Will be used by reloc_control::dirty_subvol_roots.
+ */
+ struct list_head reloc_dirty_list;
+
/*
* Number of currently running SEND ioctls to prevent
* manipulation with the read-only status via SUBVOL_SETFLAGS
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 8da2f380d3c0..bfefa1de0455 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1175,6 +1175,7 @@ static void __setup_root(struct btrfs_root *root, struct
btrfs_fs_info *fs_info,
INIT_LIST_HEAD(&root->delalloc_root);
INIT_LIST_HEAD(&root->ordered_extents);
INIT_LIST_HEAD(&root->ordered_root);
+ INIT_LIST_HEAD(&root->reloc_dirty_list);
INIT_LIST_HEAD(&root->logged_list[0]);
INIT_LIST_HEAD(&root->logged_list[1]);
spin_lock_init(&root->inode_lock);
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 272b287f8cf0..70a3e1170e8a 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -162,6 +162,8 @@ struct reloc_control {
struct mapping_tree reloc_root_tree;
/* list of reloc trees */
struct list_head reloc_roots;
+ /* list of subvolume trees who get relocated */
+ struct list_head dirty_subvol_roots;
/* size of metadata reservation for merging reloc trees */
u64 merging_rsv_size;
/* size of relocated tree nodes */
@@ -1467,15 +1469,17 @@ int btrfs_update_reloc_root(struct btrfs_trans_handle
*trans,
struct btrfs_root_item *root_item;
int ret;
- if (!root->reloc_root)
+ if (test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state) ||
+ !root->reloc_root)
goto out;
reloc_root = root->reloc_root;
root_item = &reloc_root->root_item;
+ /* root->reloc_root will stay until current relocation finished */
if (fs_info->reloc_ctl->merge_reloc_tree &&
btrfs_root_refs(root_item) == 0) {
- root->reloc_root = NULL;
+ set_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state);
__del_reloc_root(reloc_root);
}
@@ -2120,6 +2124,59 @@ static int find_next_key(struct btrfs_path *path, int
level,
return 1;
}
+/*
+ * Helper to insert current subvolume into reloc_control::dirty_subvol_roots
+ */
+static void insert_dirty_subvol(struct btrfs_trans_handle *trans,
+ struct reloc_control *rc,
+ struct btrfs_root *root)
+{
+ struct btrfs_root *reloc_root = root->reloc_root;
+ struct btrfs_root_item *reloc_root_item;
+ u64 root_objectid = root->root_key.objectid;
+
+ /* @root must be a subvolume tree root with a valid reloc tree */
+ ASSERT(root_objectid != BTRFS_TREE_RELOC_OBJECTID);
+ ASSERT(reloc_root);
+
+ reloc_root_item = &reloc_root->root_item;
+ memset(&reloc_root_item->drop_progress, 0,
+ sizeof(reloc_root_item->drop_progress));
+ reloc_root_item->drop_level = 0;
+ btrfs_set_root_refs(reloc_root_item, 0);
+ btrfs_update_reloc_root(trans, root);
+
+ if (list_empty(&root->reloc_dirty_list)) {
+ btrfs_grab_fs_root(root);
+ list_add_tail(&root->reloc_dirty_list, &rc->dirty_subvol_roots);
+ }
+ return;
+}
+
+static int clean_dirty_subvols(struct reloc_control *rc)
+{
+ struct btrfs_root *root;
+ struct btrfs_root *next;
+ int ret = 0;
+ int tmp_ret;
+
+ list_for_each_entry_safe(root, next, &rc->dirty_subvol_roots,
+ reloc_dirty_list) {
+ struct btrfs_root *reloc_root = root->reloc_root;
+
+ clear_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state);
+ list_del_init(&root->reloc_dirty_list);
+ root->reloc_root = NULL;
+ if (reloc_root) {
+ tmp_ret = btrfs_drop_snapshot(reloc_root, NULL, 0, 1);
+ if (tmp_ret < 0 && !ret)
+ ret = tmp_ret;
+ }
+ btrfs_put_fs_root(root);
+ }
+ return ret;
+}
+
/*
* merge the relocated tree blocks in reloc tree with corresponding
* fs tree.
@@ -2259,13 +2316,8 @@ static noinline_for_stack int merge_reloc_root(struct
reloc_control *rc,
out:
btrfs_free_path(path);
- if (err == 0) {
- memset(&root_item->drop_progress, 0,
- sizeof(root_item->drop_progress));
- root_item->drop_level = 0;
- btrfs_set_root_refs(root_item, 0);
- btrfs_update_reloc_root(trans, root);
- }
+ if (err == 0)
+ insert_dirty_subvol(trans, rc, root);
if (trans)
btrfs_end_transaction_throttle(trans);
@@ -2410,14 +2462,6 @@ void merge_reloc_roots(struct reloc_control *rc)
} else {
list_del_init(&reloc_root->root_list);
}
-
- ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
- if (ret < 0) {
- if (list_empty(&reloc_root->root_list))
- list_add_tail(&reloc_root->root_list,
- &reloc_roots);
- goto out;
- }
}
if (found) {
@@ -4079,6 +4123,9 @@ static noinline_for_stack int relocate_block_group(struct
reloc_control *rc)
goto out_free;
}
btrfs_commit_transaction(trans);
+ ret = clean_dirty_subvols(rc);
+ if (ret < 0 && !err)
+ err = ret;
out_free:
btrfs_free_block_rsv(fs_info, rc->block_rsv);
btrfs_free_path(path);
@@ -4173,6 +4220,7 @@ static struct reloc_control *alloc_reloc_control(void)
return NULL;
INIT_LIST_HEAD(&rc->reloc_roots);
+ INIT_LIST_HEAD(&rc->dirty_subvol_roots);
backref_cache_init(&rc->backref_cache);
mapping_tree_init(&rc->reloc_root_tree);
extent_io_tree_init(&rc->processed_blocks, NULL);
@@ -4468,6 +4516,10 @@ int btrfs_recover_relocation(struct btrfs_root *root)
goto out_free;
}
err = btrfs_commit_transaction(trans);
+
+ ret = clean_dirty_subvols(rc);
+ if (ret < 0 && !err)
+ err = ret;
out_free:
kfree(rc);
out:
--
2.20.1
