That is a good point. As it turns out there is a cheap way to add this
extra check. sys-rename has a bit of code that looks like this (which
was part of a fix to some rename bugs I ran into a while back):
if(attr->objtype == PVFS_TYPE_DIRECTORY && attr->u.dir.dirent_count != 0)
{
js_p->error_code = -PVFS_ENOTEMPTY;
return(1);
}
I think remove could do the same thing. sys-remove already retrieve the
attributes, so there is no extra cost involved in checking the
dirent_count on the client side before proceeding.
There isn't any way to 100% protect against race conditions if directory
renames/removals are driven from the client, but this check would help a
lot.
-Phil
Julian Martin Kunkel wrote:
Hi,
I have a question, if a client wants to remove a handle first the directory
entry is removed and then the client verifies if a directory is going to be
removed.
If a non empty directory is going to be removed the client just creates the
directory entry again for the parent directory, because it is not allowed to
remove a non emtpy directory.
Ok, but what happens with a filled directory if a client somehow breaks while
trying to remove ? If it breaks after removing the dirent and before
recreating the dirent, will the whole non-empty directory be lost ?
Wouldn't it be better to first verify that the directory is empty ?
I understand that after one client has verified the directory to remove is
empty another client might create some files.
So I think it would be better to verify the emptiness twice. Directories which
already have some entries could be never messed up this way.
Or is there already a cool mechanism I did not realize to circumvent that
problem ?
Thanks for your reply.
Have a nice day,
Julian
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