prevents the system to allocate caches for files that don't use or have
a file cache (ie. only those can be mmap()ed!).
Therefore, cache_prefetch() no longer crashes when trying to prefetch
files without a file cache.
read_into_cache() no longer does anything if the requested size is 0.
Fixed a bug in cache_prefetch_vnode(): if the cache couldn't be retrieved,
it put the vnode, but didn't own it (the caller does).
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@13904 a95241bf-73f2-0310-859d-f6bbb57e9c96
Axel Dörfler
eab435cd59