[03/43] btrfs: make btrfs_find_orphan_roots use btrfs_get_fs_root

Commit Message

Josef Bacik Jan. 17, 2020, 9:25 p.m. UTC

btrfs_find_orphan_roots has this weird thing where it looks up the root
in cache to see if it is there before just reading the root.  But the
read it uses just reads the root, it doesn't do any of the init work, we
do that by hand here.  But this is unnecessary, all we really want is to
see if the root still exists and add it to the dead roots list to be
cleaned up, otherwise we delete the orphan item.

Fix this by just using btrfs_get_fs_root directly with check_ref set to
false so we get the orphan root items.  Then we just handle in cache and
out of cache roots the same, add them to the dead roots list and carry
on.

Signed-off-by: Josef Bacik <[e-mail]>
---
 fs/btrfs/root-tree.c | 37 +++----------------------------------
 1 file changed, 3 insertions(+), 34 deletions(-)

Comments

Nikolay Borisov Jan. 20, 2020, 5:36 p.m. UTC | #1

On 17.01.20 г. 23:25 ч., Josef Bacik wrote:
> btrfs_find_orphan_roots has this weird thing where it looks up the root
> in cache to see if it is there before just reading the root.  But the
> read it uses just reads the root, it doesn't do any of the init work, we

The first part of this sentence must be reworded since it's gibberish as
it is.

> do that by hand here.  But this is unnecessary, all we really want is to
> see if the root still exists and add it to the dead roots list to be
> cleaned up, otherwise we delete the orphan item.
> 
> Fix this by just using btrfs_get_fs_root directly with check_ref set to
> false so we get the orphan root items.  Then we just handle in cache and
> out of cache roots the same, add them to the dead roots list and carry
> on.
> 
> Signed-off-by: Josef Bacik <[e-mail]>

Other than that I agree that btrfs_get_fs_root already has the necessary
processing for orphan roots.

Reviewed-by: Nikolay Borisov <[e-mail]>

Patch

diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index 612411c74550..094a71c54fa1 100644
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -255,25 +255,7 @@  int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
 		root_key.objectid = key.offset;
 		key.offset++;
 
-		/*
-		 * The root might have been inserted already, as before we look
-		 * for orphan roots, log replay might have happened, which
-		 * triggers a transaction commit and qgroup accounting, which
-		 * in turn reads and inserts fs roots while doing backref
-		 * walking.
-		 */
-		root = btrfs_lookup_fs_root(fs_info, root_key.objectid);
-		if (root) {
-			WARN_ON(!test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED,
-					  &root->state));
-			if (btrfs_root_refs(&root->root_item) == 0) {
-				set_bit(BTRFS_ROOT_DEAD_TREE, &root->state);
-				btrfs_add_dead_root(root);
-			}
-			continue;
-		}
-
-		root = btrfs_read_fs_root(tree_root, &root_key);
+		root = btrfs_get_fs_root(fs_info, &root_key, false);
 		err = PTR_ERR_OR_ZERO(root);
 		if (err && err != -ENOENT) {
 			break;
@@ -300,21 +282,8 @@  int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
 			continue;
 		}
 
-		err = btrfs_init_fs_root(root);
-		if (err) {
-			btrfs_free_fs_root(root);
-			break;
-		}
-
-		set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state);
-
-		err = btrfs_insert_fs_root(fs_info, root);
-		if (err) {
-			BUG_ON(err == -EEXIST);
-			btrfs_free_fs_root(root);
-			break;
-		}
-
+		WARN_ON(!test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED,
+				  &root->state));
 		if (btrfs_root_refs(&root->root_item) == 0) {
 			set_bit(BTRFS_ROOT_DEAD_TREE, &root->state);
 			btrfs_add_dead_root(root);