osdc: pass fadvise op flags to WritebackHandler read requests

librbd was previously attempting to cast the provided Context to
retrieve the fadvise flags.  To eliminate the unsafe cast, now
the fadvise flags are directly passed to the WritebackHandler::read
callback.

Fixes: ceph#10914
Signed-off-by: Jason Dillaman <[email protected]>

src/client/ObjecterWriteback.h

@@ -17,7 +17,7 @@ class ObjecterWriteback : public WritebackHandler {
   virtual void read(const object_t& oid, uint64_t object_no,
 		    const object_locator_t& oloc, uint64_t off, uint64_t len,
 		    snapid_t snapid, bufferlist *pbl, uint64_t trunc_size,
-		    __u32 trunc_seq, Context *onfinish) {
+		    __u32 trunc_seq, int op_flags, Context *onfinish) {
     m_objecter->read_trunc(oid, oloc, off, len, snapid, pbl, 0,
 			   trunc_size, trunc_seq,
 			   new C_OnFinisher(new C_Lock(m_lock, onfinish),

src/librbd/AioCompletion.h

@@ -146,9 +146,6 @@ namespace librbd {
     void set_req(AioRead *req) {
       m_req = req;
     }
-    AioRead *get_req() {
-      return m_req;
-    }
   private:
     CephContext *m_cct;
     AioCompletion *m_completion;

src/librbd/AioRequest.h

@@ -77,10 +77,6 @@ namespace librbd {
       return m_read_data;
     }
 
-    int get_op_flags() {
-      return m_op_flags;
-    }
-
     std::map<uint64_t, uint64_t> m_ext_map;
 
     friend class C_AioRead;

src/librbd/LibrbdWriteback.cc

@@ -102,7 +102,7 @@ namespace librbd {
 			     const object_locator_t& oloc,
 			     uint64_t off, uint64_t len, snapid_t snapid,
 			     bufferlist *pbl, uint64_t trunc_size,
-			     __u32 trunc_seq, Context *onfinish)
+			     __u32 trunc_seq, int op_flags, Context *onfinish)
   {
     // on completion, take the mutex and then call onfinish.
     Context *req = new C_Request(m_ictx->cct, onfinish, &m_lock);
@@ -120,10 +120,7 @@ namespace librbd {
       librados::Rados::aio_create_completion(req, context_cb, NULL);
     librados::ObjectReadOperation op;
     op.read(off, len, pbl, NULL);
-    {
-      AioRead *req = (static_cast<C_AioRead *>(onfinish))->get_req();
-      op.set_op_flags2((uint32_t)req->get_op_flags());
-    }
+    op.set_op_flags2(op_flags);
     int flags = m_ictx->get_read_flags(snapid);
     int r = m_ictx->data_ctx.aio_operate(oid.name, rados_completion, &op,
 					 flags, NULL);

src/librbd/LibrbdWriteback.h

@@ -27,7 +27,7 @@ namespace librbd {
     virtual void read(const object_t& oid, uint64_t object_no,
 		      const object_locator_t& oloc, uint64_t off, uint64_t len,
 		      snapid_t snapid, bufferlist *pbl, uint64_t trunc_size,
-		      __u32 trunc_seq, Context *onfinish);
+		      __u32 trunc_seq, int op_flags, Context *onfinish);
 
     // Determine whether a read to this extent could be affected by a write-triggered copy-on-write
     virtual bool may_copy_on_write(const object_t& oid, uint64_t read_off, uint64_t read_len, snapid_t snapid);

src/osdc/ObjectCacher.cc

@@ -631,7 +631,7 @@ void ObjectCacher::close_object(Object *ob)
 
 
 
-void ObjectCacher::bh_read(BufferHead *bh)
+void ObjectCacher::bh_read(BufferHead *bh, int op_flags)
 {
   assert(lock.is_locked());
   ldout(cct, 7) << "bh_read on " << *bh << " outstanding reads "
@@ -647,7 +647,8 @@ void ObjectCacher::bh_read(BufferHead *bh)
   writeback_handler.read(bh->ob->get_oid(), bh->ob->get_object_number(),
 			 bh->ob->get_oloc(), bh->start(), bh->length(),
 			 bh->ob->get_snap(), &onfinish->bl,
-			 bh->ob->truncate_size, bh->ob->truncate_seq, onfinish);
+			 bh->ob->truncate_size, bh->ob->truncate_seq,
+			 op_flags, onfinish);
 
   ++reads_outstanding;
 }
@@ -1157,7 +1158,7 @@ int ObjectCacher::_readx(OSDRead *rd, ObjectSet *oset, Context *onfinish,
 	  bh_remove(o, bh_it->second);
 	  delete bh_it->second;
 	} else {
-	  bh_read(bh_it->second);
+	  bh_read(bh_it->second, rd->fadvise_flags);
 	  if (success && onfinish) {
 	    ldout(cct, 10) << "readx missed, waiting on " << *bh_it->second
 			   << " off " << bh_it->first << dendl;

src/osdc/ObjectCacher.h

@@ -453,7 +453,7 @@ class ObjectCacher {
   void bh_remove(Object *ob, BufferHead *bh);
 
   // io
-  void bh_read(BufferHead *bh);
+  void bh_read(BufferHead *bh, int op_flags);
   void bh_write(BufferHead *bh);
 
   void trim();

src/osdc/WritebackHandler.h

@@ -15,7 +15,7 @@ class WritebackHandler {
   virtual void read(const object_t& oid, uint64_t object_no,
 		    const object_locator_t& oloc, uint64_t off, uint64_t len,
 		    snapid_t snapid, bufferlist *pbl, uint64_t trunc_size,
-		    __u32 trunc_seq, Context *onfinish) = 0;
+		    __u32 trunc_seq, int op_flags, Context *onfinish) = 0;
   /**
    * check if a given extent read result may change due to a write
    *

src/test/osdc/FakeWriteback.cc

@@ -62,7 +62,7 @@ void FakeWriteback::read(const object_t& oid, uint64_t object_no,
 			 const object_locator_t& oloc,
 			 uint64_t off, uint64_t len, snapid_t snapid,
 			 bufferlist *pbl, uint64_t trunc_size,
-			 __u32 trunc_seq, Context *onfinish)
+			 __u32 trunc_seq, int op_flags, Context *onfinish)
 {
   C_Delay *wrapper = new C_Delay(m_cct, onfinish, m_lock, off, pbl, m_delay_ns);
   m_finisher->queue(wrapper, len);

src/test/osdc/FakeWriteback.h

@@ -20,7 +20,7 @@ class FakeWriteback : public WritebackHandler {
   virtual void read(const object_t& oid, uint64_t object_no,
 		    const object_locator_t& oloc, uint64_t off, uint64_t len,
 		    snapid_t snapid, bufferlist *pbl, uint64_t trunc_size,
-		    __u32 trunc_seq, Context *onfinish);
+		    __u32 trunc_seq, int op_flags, Context *onfinish);
 
   virtual ceph_tid_t write(const object_t& oid, const object_locator_t& oloc,
 		           uint64_t off, uint64_t len,