+/*
+ * This is used only for read-ahead. Failures or difficult to handle
+ * situations are safe to ignore.
+ *
+ * Right now, we don't bother with BH_Boundary - in-inode extent lists
+ * are quite large (243 extents on 4k blocks), so most inodes don't
+ * grow out to a tree. If need be, detecting boundary extents could
+ * trivially be added in a future version of ocfs2_get_block().
+ */
+static int ocfs2_readpages(struct file *filp, struct address_space *mapping,
+ struct list_head *pages, unsigned nr_pages)
+{
+ int ret, err = -EIO;
+ struct inode *inode = mapping->host;
+ struct ocfs2_inode_info *oi = OCFS2_I(inode);
+ loff_t start;
+ struct page *last;
+
+ /*
+ * Use the nonblocking flag for the dlm code to avoid page
+ * lock inversion, but don't bother with retrying.
+ */
+ ret = ocfs2_inode_lock_full(inode, NULL, 0, OCFS2_LOCK_NONBLOCK);
+ if (ret)
+ return err;
+
+ if (down_read_trylock(&oi->ip_alloc_sem) == 0) {
+ ocfs2_inode_unlock(inode, 0);
+ return err;
+ }
+
+ /*
+ * Don't bother with inline-data. There isn't anything
+ * to read-ahead in that case anyway...
+ */
+ if (oi->ip_dyn_features & OCFS2_INLINE_DATA_FL)
+ goto out_unlock;
+
+ /*
+ * Check whether a remote node truncated this file - we just
+ * drop out in that case as it's not worth handling here.
+ */
+ last = list_entry(pages->prev, struct page, lru);
+ start = (loff_t)last->index << PAGE_CACHE_SHIFT;
+ if (start >= i_size_read(inode))
+ goto out_unlock;
+
+ err = mpage_readpages(mapping, pages, nr_pages, ocfs2_get_block);
+
+out_unlock:
+ up_read(&oi->ip_alloc_sem);
+ ocfs2_inode_unlock(inode, 0);
+
+ return err;
+}
+