[$] Limiting negative dentries

A number of problems related to negative directory entries (dentries) werethe topic of a filesystem-track session atthe 2026 Linux Storage,Filesystem, Memory Management, and BPF Summit. Negative dentries areused to indicate that a file of a given name does not exist in a directory;it is an optimization that short-circuits the lookup of the file name whenthe answer is already known.Miklos Szeredi led asession that discussedsome problems that come from having too many negative dentries for adirectory.