On Monday September 10, [email protected] wrote:
> On Mon, Sep 10, 2007 at 02:46:32PM -0400, J. Bruce Fields wrote:
> > * This forceful removal will result in ugly /proc output if
> > * somebody holds a file open that got deleted due to a rename.
> > * We could be nicer about the deleted file, and let it show
> > - * up under the name it got deleted rather than the name that
> > - * deleted it.
> > + * up under the name it had before it was deleted rather than
> > + * under the original name of the file that was moved on top of it.
>
> By the way, on further examination of the code it doesn't actually do
> what's described in the case where the target name is large and the
> moved-from name is small. Instead, it reports random garbage (usually
> part of a name left over from some other dentry?) as far as I can tell:
>
> from switch_names():
>
>
> if (dname_external(target)) {
> if (dname_external(dentry)) {
> ...
> } else {
> /*
> * dentry:internal, target:external. Steal target's
> * storage and make target internal.
> */
> dentry->d_name.name = target->d_name.name;
> target->d_name.name = target->d_iname;
>
> ... but target->d_iname could have anything in it, right?
Right, but not relevant.
The name "switch_names" is somewhat misleading. It is really
"copyname" or similar. From the comment at the top:
* When switching names, the actual string doesn't strictly have to
* be preserved in the target - because we're dropping the target
* anyway. As such, we can just do a simple memcpy() to copy over
* the new name before we switch.
so the apparent name of 'target' after the 'swap' is not important.
The purpose of the assignment
target->d_name.name = target->d_iname;
is to make "dname_external(target)" false, that making "target
internal" as the comment says.
static inline int dname_external(struct dentry *dentry)
{
return dentry->d_name.name != dentry->d_iname;
}
This could possibly be made a little more clear....
NeilBrown
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