Shyam Prasad N <nspmangalore@xxxxxxxxx> writes: > Ideally, negative dentries should allow a filename lookup to happen > entirely from the dentry cache if the lookup had happened once > already. But I noticed that the SMB client goes to the server every > time we do a stat of a file that does not exist. This is a network filesystem. If the last lookup ended up with a negative dentry in dcache, that doesn't mean the file won't exist the next time we look it up again. The file could have been created by a different client, so we need to query it on server. > I investigated this more and it looks like vfs_getattr does make use > of negative dentry, but the revalidate always comes to > cifs_d_revalidate even for negative dentries. And we do not have the > code necessary to deal with it. I think we do. Check the places where we return 0 from cifs_d_revalidate(), meaning that the dentry will need to be looked up again and hopefully instantiated (e.g. file was created on server). > We do use d_really_is_positive before we do the dentry validation, but > it looks like that comes to us as success, even in case of > non-existent dentries. Is this expected? I don't think so. Al, am I missing someting?
