On Fri, Feb 07, 2014 at 05:49:06PM +0100, Miklos Szeredi wrote:
> From: Miklos Szeredi <mszer...@suse.cz>
>
> If flags contain RENAME_EXCHANGE then exchange source and destination files.
> There's no restriction on the type of the files; e.g. a directory can be
> exchanged with a symlink.
>
> Signed-off-by: Miklos Szeredi <mszer...@suse.cz>
> Reviewed-by: Jan Kara <j...@suse.cz>
I don't see any problem with the delegation stuff. Some random
bikeshedding:
> @@ -2575,6 +2579,10 @@ static void __d_move(struct dentry * dentry, struct
> dentry * target)
>
> /* Unhash the target: dput() will then get rid of it */
I never understood the point of this comment. It's not even right, is
it? And if anything this makes it less so. Delete?
> __d_drop(target);
> + if (exchange) {
> + __d_rehash(target,
> + d_hash(dentry->d_parent, dentry->d_name.hash));
> + }
>
> list_del(&dentry->d_u.d_child);
> list_del(&target->d_u.d_child);
...
> @@ -4042,7 +4057,7 @@ int vfs_rename(struct inode *old_dir, struct dentry
> *old_dentry,
>
> old_name = fsnotify_oldname_init(old_dentry->d_name.name);
> dget(new_dentry);
> - if (!is_dir)
> + if (!is_dir || (flags & RENAME_EXCHANGE))
> lock_two_nondirectories(source, target);
> else if (target)
> mutex_lock(&target->i_mutex);
I had to stop to think about that for a minute: OK, so in the normal
rename case we still need to lock the to-be-deleted target, and
lock_two_nondirectories won't do that for us because it ignores
directories. Got it.
This feels a bit ugly but I don't have a better idea.
> @@ -4051,25 +4066,25 @@ int vfs_rename(struct inode *old_dir, struct dentry
> *old_dentry,
Most of this function is under (flags & RENAME_EXCHANGE) conditionals at
this point. Have you looked at how much is duplicated if you split this
into something like vfs_rename and vfs_exchange?
--b.
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