+static int nfs_ctime_need_update(const struct inode *inode, const struct nfs_fattr *fattr)
+{
+ if (!(fattr->valid & NFS_ATTR_FATTR_CTIME))
+ return 0;
+ return timespec_compare(&fattr->ctime, &inode->i_ctime) > 0;
+}
+
+static int nfs_size_need_update(const struct inode *inode, const struct nfs_fattr *fattr)
+{
+ if (!(fattr->valid & NFS_ATTR_FATTR_SIZE))
+ return 0;
+ return nfs_size_to_loff_t(fattr->size) > i_size_read(inode);
+}
+
+static atomic_long_t nfs_attr_generation_counter;
+
+static unsigned long nfs_read_attr_generation_counter(void)
+{
+ return atomic_long_read(&nfs_attr_generation_counter);
+}
+
+unsigned long nfs_inc_attr_generation_counter(void)
+{
+ return atomic_long_inc_return(&nfs_attr_generation_counter);
+}
+
+void nfs_fattr_init(struct nfs_fattr *fattr)
+{
+ fattr->valid = 0;
+ fattr->time_start = jiffies;
+ fattr->gencount = nfs_inc_attr_generation_counter();
+}
+
+/**
+ * nfs_inode_attrs_need_update - check if the inode attributes need updating
+ * @inode - pointer to inode
+ * @fattr - attributes
+ *
+ * Attempt to divine whether or not an RPC call reply carrying stale
+ * attributes got scheduled after another call carrying updated ones.
+ *
+ * To do so, the function first assumes that a more recent ctime means
+ * that the attributes in fattr are newer, however it also attempt to
+ * catch the case where ctime either didn't change, or went backwards
+ * (if someone reset the clock on the server) by looking at whether
+ * or not this RPC call was started after the inode was last updated.
+ * Note also the check for wraparound of 'attr_gencount'
+ *
+ * The function returns 'true' if it thinks the attributes in 'fattr' are
+ * more recent than the ones cached in the inode.
+ *
+ */
+static int nfs_inode_attrs_need_update(const struct inode *inode, const struct nfs_fattr *fattr)
+{
+ const struct nfs_inode *nfsi = NFS_I(inode);
+
+ return ((long)fattr->gencount - (long)nfsi->attr_gencount) > 0 ||
+ nfs_ctime_need_update(inode, fattr) ||
+ nfs_size_need_update(inode, fattr) ||
+ ((long)nfsi->attr_gencount - (long)nfs_read_attr_generation_counter() > 0);
+}
+
+static int nfs_refresh_inode_locked(struct inode *inode, struct nfs_fattr *fattr)
+{
+ if (nfs_inode_attrs_need_update(inode, fattr))
+ return nfs_update_inode(inode, fattr);
+ return nfs_check_inode_attributes(inode, fattr);
+}
+