On Thu, Mar 28, 2019 at 09:42:59PM +0800, Qu Wenruo wrote:
>
>
> On 2019/3/28 下午9:38, David Sterba wrote:
> > On Wed, Mar 20, 2019 at 02:37:16PM +0800, Qu Wenruo wrote:
> >> + if (S_ISDIR(mode) && btrfs_inode_nlink(leaf, iitem) > 1) {
> >> + inode_item_err(fs_info, leaf, slot,
> >> + "invalid nlink: has %u expect no more than 1 for dir",
> >> + btrfs_inode_nlink(leaf, iitem));
> >> + goto error;
> >> + }
> >
> > I'm not sure about this check, the number of links for a directory is 1,
> > but the exact count could be implemented (there's a project idea for
> > that). I don't know if this will require an incompat bit or not.
>
> That means we have hard link for directories.
Yes, hard links of directories are forbidden by VFS but that's not the
point here:
https://btrfs.wiki.kernel.org/index.php/Project_ideas#Track_link_count_for_directories
"The link count for directories is traditionally used to count the number
of subdirectores iff the link count is >= 2."
