Hi, Kent
On 9/26/25 11:42, Kent Overstreet wrote:
On Fri, Sep 26, 2025 at 10:21:50AM +0800, Youling Tang wrote:
From: Youling Tang <[email protected]>
Currently bcachefs only performs link count checks during link operations,
during rename and mkdir operations, the link count should also be checked.
This patch moves the checks to the vfs_{link,rename,mkdir} functions when
sb->s_max_links is set, eliminating the need for filesystem-specific checks.
Signed-off-by: Youling Tang <[email protected]>
I applied the other two patches, but not this one. We can't rely on the
VFS for checks like this, there's lots of routes to modifying the
filesystem that don't go through the VFS.
```
vfs_link
bch2_link
__bch2_link
bch2_link_trans
bch2_inode_nlink_inc
bch2_symlink
__bch2_link
```
I have traversed the bcachefs code and found that bch2_inode_nlink_inc is
called only once by bch2_link_trans, which in turn is called only once
by __bch2_link.
Although __bch2_link is also called by bch2_symlink, symlink operations
don't involve i_nlink values. Therefore, all effective calls to
bch2_inode_nlink_incoriginate from vfs_link. Please let me know if
there are any calls from other sources.
Even without moving to the VFS layer, do we still need to add link count
validation in bch2_{mkdir, rename}?
Thanks,
Youling.
