Allow the cache to be invalidated when page(s) have gone missing. In this
case increment the version of the cache and reset to an empty state.
Add a version number to the directory stream in struct fuse_file as well,
indicating the version of the cache it's supposed to be reading. If the
cache version doesn't match the stream's version, then reset the stream to
the beginning of the cache.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
The cache is only used if it's completed, not while it's still being
filled; this constraint could be lifted later, if it turns out to be
useful.
Introduce state in struct fuse_file that indicates the position within the
cache. After a seek, reset the position to the beginning of the cache and
search the cache for the current position. If the current position is not
found in the cache, then fall back to uncached readdir.
It can also happen that page(s) disappear from the cache, in which case we
must also fall back to uncached readdir.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This patch just adds the cache filling functions, which are invoked if
FOPEN_CACHE_DIR flag is set in the OPENDIR reply.
Cache reading and cache invalidation are added by subsequent patches.
The directory cache uses the page cache. Directory entries are packed into
a page in the same format as in the READDIR reply. A page only contains
whole entries, the space at the end of the page is cleared. The page is
locked while being modified.
Multiple parallel readdirs on the same directory can fill the cache; the
only constraint is that continuity must be maintained (d_off of last entry
points to position of current entry).
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
