sunrpc: add a new cache_detail operation for when a cache is flushed

When the exports table is changed, exportfs will usually write a new
time to the "flush" file in the nfsd.export cache procfile. This tells
the kernel to flush any entries that are older than that value.

This gives us a mechanism to tell whether an unexport might have
occurred. Add a new ->flush cache_detail operation that is called after
flushing the cache whenever someone writes to a "flush" file.

Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h
index f7d086b77a21a152d3f0352cb169ae1b17c48a80..f8603724fbee2557e7264a5e3681796f2d6b0ee7 100644 (file)
--- a/include/linux/sunrpc/cache.h
+++ b/include/linux/sunrpc/cache.h
@@ -87,6 +87,7 @@ struct cache_detail {
                                              int has_died);
 
        struct cache_head *     (*alloc)(void);
+       void                    (*flush)(void);
        int                     (*match)(struct cache_head *orig, struct cache_head *new);
        void                    (*init)(struct cache_head *orig, struct cache_head *new);
        void                    (*update)(struct cache_head *orig, struct cache_head *new);

diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index a6a6190ad37a98f3ccfb0d92e5edab063f0e85de..a349094f6fb7d90c31391bf0fde9bd743e0bd429 100644 (file)
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -1524,6 +1524,9 @@ static ssize_t write_flush(struct file *file, const char __user *buf,
        cd->nextcheck = now;
        cache_flush();
 
+       if (cd->flush)
+               cd->flush();
+
        *ppos += count;
        return count;
 }