Al Viro <viro@xxxxxxxxxxxxxxxxxx> writes:
> On Fri, Aug 28, 2020 at 10:40:35PM +0200, Florian Margaine wrote:
>> There's currently this seemingly unnecessary limitation that rename()
>> cannot work over bind mounts of the same filesystem,
>
> ... is absolutely deliberate - that's how you set a boundary in the
> tree, preventing both links and renames across it.
Sorry, I'm not not sure I understand what you're saying.
As I understand it, the tree is the superblock there, not the mount. As
in, the dentries are relative to the superblock, and the mountpoint is
no more than a pointer to a superblock's dentry.
In addition, I noticed this snippet in fs/read_write.c:
/*
* FICLONE/FICLONERANGE ioctls enforce that src and dest files are on
* the same mount. Practically, they only need to be on the same file
* system.
*/
if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
return -EXDEV;
Which seems to confirm my understanding.
What am I getting wrong there?
>
> Incidentally, doing that would have fun effects for anyone with current
> directory inside the subtree you'd moved - try and see.
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