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btrfs: do not utilize goto to implement delayed inode ref deletion

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[PROBLEM]
The function __btrfs_update_delayed_inode() is doing something not
meeting the code standard of today:

	path->slots[0]++
	if (path->slots[0] >= btrfs_header_nritems(leaf))
		goto search;
again:
	if (!is_the_target_inode_ref())
		goto out;
	ret = btrfs_delete_item();
	/* Some cleanup. */
	return ret;

search:
	ret = search_for_the_last_inode_ref();
	goto again;

With the tag named "again", it's pretty common to think it's a loop, but
the truth is, we only need to do the search once, to locate the last
(also the first, since there should only be one INODE_REF or
INODE_EXTREF now) ref of the inode.

[FIX]
Instead of the weird jumps, just do them in a stream-lined fashion.
This removes those weird labels, and add extra comments on why we can do
the different searches.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2023-10-31 07:37:20 +10:30 committed by David Sterba
parent 80d197fe04
commit 9ba7c686fe
1 changed files with 24 additions and 21 deletions
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43
fs/btrfs/delayed-inode.c
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@ -1036,14 +1036,33 @@ static int __btrfs_update_delayed_inode(struct btrfs_trans_handle *trans,
if (!test_bit(BTRFS_DELAYED_NODE_DEL_IREF, &node->flags))
goto out;
/*
* Now we're going to delete the INODE_REF/EXTREF, which should be the
* only one ref left. Check if the next item is an INODE_REF/EXTREF.
*
* But if we're the last item already, release and search for the last
* INODE_REF/EXTREF.
*/
if (path->slots[0] + 1 >= btrfs_header_nritems(leaf)) {
key.objectid = node->inode_id;
key.type = BTRFS_INODE_EXTREF_KEY;
key.offset = (u64)-1;
btrfs_release_path(path);
ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
if (ret < 0)
goto err_out;
ASSERT(ret > 0);
ASSERT(path->slots[0] > 0);
ret = 0;
path->slots[0]--;
leaf = path->nodes[0];
} else {
path->slots[0]++;
if (path->slots[0] >= btrfs_header_nritems(leaf))
goto search;
again:
}
btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
if (key.objectid != node->inode_id)
goto out;
if (key.type != BTRFS_INODE_REF_KEY &&
key.type != BTRFS_INODE_EXTREF_KEY)
goto out;
@ -1070,22 +1089,6 @@ err_out:
btrfs_abort_transaction(trans, ret);
return ret;
search:
btrfs_release_path(path);
key.type = BTRFS_INODE_EXTREF_KEY;
key.offset = -1;
ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
if (ret < 0)
goto err_out;
ASSERT(ret);
ret = 0;
leaf = path->nodes[0];
path->slots[0]--;
goto again;
}
static inline int btrfs_update_delayed_inode(struct btrfs_trans_handle *trans,