Merge pull request #22841 from pdvian/wip-24541-mimic

mimic: mds: add magic to header of open file table

Reviewed-by: Patrick Donnelly <pdonnell@redhat.com>

src/mds/OpenFileTable.cc

@@ -195,9 +195,13 @@ object_t OpenFileTable::get_object_name(unsigned idx) const
 
 void OpenFileTable::_encode_header(bufferlist &bl, int j_state)
 {
+  std::string_view magic = CEPH_FS_ONDISK_MAGIC;
+  encode(magic, bl);
+  ENCODE_START(1, 1, bl);
   encode(omap_version, bl);
   encode(omap_num_objs, bl);
   encode((__u8)j_state, bl);
+  ENCODE_FINISH(bl);
 }
 
 class C_IO_OFT_Save : public MDSIOContextBase {
@@ -292,7 +296,6 @@ void OpenFileTable::commit(MDSInternalContextBase *c, uint64_t log_seq, int op_p
   SnapContext snapc;
   object_locator_t oloc(mds->mdsmap->get_metadata_pool());
 
-  const unsigned max_items_per_obj = 1024 * 1024;
   const unsigned max_write_size = mds->mdcache->max_dir_commit_size;
 
   struct omap_update_ctl {
@@ -456,11 +459,12 @@ void OpenFileTable::commit(MDSInternalContextBase *c, uint64_t log_seq, int op_p
 	assert(it.second == DIRTY_NEW);
 	// find omap object to store the key
 	for (unsigned i = first_free_idx; i < omap_num_objs; i++) {
-	  if (omap_num_items[i] < max_items_per_obj)
+	  if (omap_num_items[i] < MAX_ITEMS_PER_OBJ)
 	    omap_idx = i;
 	}
 	if (omap_idx < 0) {
 	  ++omap_num_objs;
+	  assert(omap_num_objs <= MAX_OBJECTS);
 	  omap_num_items.resize(omap_num_objs);
 	  omap_updates.resize(omap_num_objs);
 	  omap_updates.back().clear = true;
@@ -476,7 +480,7 @@ void OpenFileTable::commit(MDSInternalContextBase *c, uint64_t log_seq, int op_p
       unsigned& count = omap_num_items.at(omap_idx);
       assert(count > 0);
       --count;
-      if ((unsigned)omap_idx < first_free_idx && count < max_items_per_obj)
+      if ((unsigned)omap_idx < first_free_idx && count < MAX_ITEMS_PER_OBJ)
 	first_free_idx = omap_idx;
     }
     auto& ctl = omap_updates.at(omap_idx);
@@ -713,12 +717,42 @@ void OpenFileTable::_load_finish(int op_r, int header_r, int values_r,
   try {
     if (first) {
       bufferlist::iterator p = header_bl.begin();
+
+      string magic;
       version_t version;
       unsigned num_objs;
       __u8 jstate;
-      decode(version, p);
-      decode(num_objs, p);
-      decode(jstate, p);
+
+      if (header_bl.length() == 13) {
+	// obsolete format.
+	decode(version, p);
+	decode(num_objs, p);
+	decode(jstate, p);
+      } else {
+	decode(magic, p);
+	if (magic != CEPH_FS_ONDISK_MAGIC) {
+	  std::ostringstream oss;
+	  oss << "invalid magic '" << magic << "'";
+	  throw buffer::malformed_input(oss.str());
+	}
+
+	DECODE_START(1, p);
+	decode(version, p);
+	decode(num_objs, p);
+	decode(jstate, p);
+	DECODE_FINISH(p);
+      }
+
+      if (num_objs > MAX_OBJECTS) {
+	  std::ostringstream oss;
+	  oss << "invalid object count '" << num_objs << "'";
+	  throw buffer::malformed_input(oss.str());
+      }
+      if (jstate > JOURNAL_FINISH) {
+	  std::ostringstream oss;
+	  oss << "invalid journal state '" << jstate << "'";
+	  throw buffer::malformed_input(oss.str());
+      }
 
       if (version > omap_version) {
 	omap_version = version;

src/mds/OpenFileTable.h

@@ -67,6 +67,9 @@ class OpenFileTable
   MDSRank *mds;
 
   version_t omap_version = 0;
+
+  static const unsigned MAX_ITEMS_PER_OBJ = 1024 * 1024;
+  static const unsigned MAX_OBJECTS = 1024; // billion items at most
   unsigned omap_num_objs = 0;
   std::vector<unsigned> omap_num_items;