1 files changed, 123 insertions, 0 deletions

diff --git a/fs/nfs/fscache-index.c b/fs/nfs/fscache-index.c
index a824050be807..7bc54acb7b00 100644
--- a/fs/nfs/fscache-index.c
+++ b/fs/nfs/fscache-index.c
@@ -146,3 +146,126 @@ const struct fscache_cookie_def nfs_fscache_super_index_def = {
         .type           = FSCACHE_COOKIE_TYPE_INDEX,
         .get_key        = nfs_super_get_key,
 };
+
+/*
+ * Definition of the auxiliary data attached to NFS inode storage objects
+ * within the cache.
+ *
+ * The contents of this struct are recorded in the on-disk local cache in the
+ * auxiliary data attached to the data storage object backing an inode.  This
+ * permits coherency to be managed when a new inode binds to an already extant
+ * cache object.
+ */
+struct nfs_fscache_inode_auxdata {
+        struct timespec mtime;
+        struct timespec ctime;
+        loff_t          size;
+        u64             change_attr;
+};
+
+/*
+ * Generate a key to describe an NFS inode in an NFS server's index
+ */
+static uint16_t nfs_fscache_inode_get_key(const void *cookie_netfs_data,
+                                          void *buffer, uint16_t bufmax)
+{
+        const struct nfs_inode *nfsi = cookie_netfs_data;
+        uint16_t nsize;
+
+        /* use the inode's NFS filehandle as the key */
+        nsize = nfsi->fh.size;
+        memcpy(buffer, nfsi->fh.data, nsize);
+        return nsize;
+}
+
+/*
+ * Get certain file attributes from the netfs data
+ * - This function can be absent for an index
+ * - Not permitted to return an error
+ * - The netfs data from the cookie being used as the source is presented
+ */
+static void nfs_fscache_inode_get_attr(const void *cookie_netfs_data,
+                                       uint64_t *size)
+{
+        const struct nfs_inode *nfsi = cookie_netfs_data;
+
+        *size = nfsi->vfs_inode.i_size;
+}
+
+/*
+ * Get the auxiliary data from netfs data
+ * - This function can be absent if the index carries no state data
+ * - Should store the auxiliary data in the buffer
+ * - Should return the amount of amount stored
+ * - Not permitted to return an error
+ * - The netfs data from the cookie being used as the source is presented
+ */
+static uint16_t nfs_fscache_inode_get_aux(const void *cookie_netfs_data,
+                                          void *buffer, uint16_t bufmax)
+{
+        struct nfs_fscache_inode_auxdata auxdata;
+        const struct nfs_inode *nfsi = cookie_netfs_data;
+
+        memset(&auxdata, 0, sizeof(auxdata));
+        auxdata.size = nfsi->vfs_inode.i_size;
+        auxdata.mtime = nfsi->vfs_inode.i_mtime;
+        auxdata.ctime = nfsi->vfs_inode.i_ctime;
+
+        if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
+                auxdata.change_attr = nfsi->change_attr;
+
+        if (bufmax > sizeof(auxdata))
+                bufmax = sizeof(auxdata);
+
+        memcpy(buffer, &auxdata, bufmax);
+        return bufmax;
+}
+
+/*
+ * Consult the netfs about the state of an object
+ * - This function can be absent if the index carries no state data
+ * - The netfs data from the cookie being used as the target is
+ *   presented, as is the auxiliary data
+ */
+static
+enum fscache_checkaux nfs_fscache_inode_check_aux(void *cookie_netfs_data,
+                                                  const void *data,
+                                                  uint16_t datalen)
+{
+        struct nfs_fscache_inode_auxdata auxdata;
+        struct nfs_inode *nfsi = cookie_netfs_data;
+
+        if (datalen != sizeof(auxdata))
+                return FSCACHE_CHECKAUX_OBSOLETE;
+
+        memset(&auxdata, 0, sizeof(auxdata));
+        auxdata.size = nfsi->vfs_inode.i_size;
+        auxdata.mtime = nfsi->vfs_inode.i_mtime;
+        auxdata.ctime = nfsi->vfs_inode.i_ctime;
+
+        if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
+                auxdata.change_attr = nfsi->change_attr;
+
+        if (memcmp(data, &auxdata, datalen) != 0)
+                return FSCACHE_CHECKAUX_OBSOLETE;
+
+        return FSCACHE_CHECKAUX_OKAY;
+}
+
+/*
+ * Define the inode object for FS-Cache.  This is used to describe an inode
+ * object to fscache_acquire_cookie().  It is keyed by the NFS file handle for
+ * an inode.
+ *
+ * Coherency is managed by comparing the copies of i_size, i_mtime and i_ctime
+ * held in the cache auxiliary data for the data storage object with those in
+ * the inode struct in memory.
+ */
+const struct fscache_cookie_def nfs_fscache_inode_object_def = {
+        .name           = "NFS.fh",
+        .type           = FSCACHE_COOKIE_TYPE_DATAFILE,
+        .get_key        = nfs_fscache_inode_get_key,
+        .get_attr       = nfs_fscache_inode_get_attr,
+        .get_aux        = nfs_fscache_inode_get_aux,
+        .check_aux      = nfs_fscache_inode_check_aux,
+};